PROJECT Pattern, Process, and Productivity of Coastal ... · study of pattern, process, and productivity in the hypermaritime forests of north coastal British Columbia. The project

2 0 0 5

Ministry of Forests Forest Science Program

Pattern, Process, and Productivityin Hypermaritime Forests

of Coastal British Columbia

S P E C I A L R E P O R T

A SYNTHESIS OF 7-YEAR RESULTS

THE HyP3 PROJECT

Ministry of ForestsForest Science Program

Pattern, Process, and Productivity

in Hypermaritime Forests

of Coastal British ColumbiaA Synthesis of 7-Year Results

Compiled & Edited by:

Allen Banner, Phil LePage, Jen Moran, & Adrian de Groot

The HyP3 Project

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Copies of this report may be obtained, depending upon supply, from:Crown Publications521 Fort Street, Victoria, BC

(250) 386-4636, www.crownpub.bc.ca

For more information on Forest Science Program publications, visit our web site at:http://www.for.gov.bc.ca/hfd/pubs/index.htm

Library and Archives Canada Cataloguing in Publication DataMain entry under title:

The HyP3 Project : pattern, process and productivity in hypermaritime forests of coastal British Columbia : a synthesis of 7-year results

(Special report series, 0843-6452 ; 10)

Includes bibliographical references: p. 0-7726-5320-8

1. Forest ecology - British Columbia - Pacific Coast. 2. Sustainable forestry - BritishColumbia - Pacific Coast. 3. Forest management - British Columbia - Pacific Coast. 4. Forests and forestry - British Columbia - Pacific Coast. I. Banner, Allen, 1954- . II. British Columbia. Forest Science Program. II Series: Special report series (BritishColumbia. Ministry of Forests) ; 10.

106.2.737 2005 333.75'09711 2005-960066-7

Prepared by

Allen Banner, R.P.Bio., R.P.F.Research Ecologist, B.C. Ministry of ForestsSmithers, BC

Phil LePage, R.P.F.Research Silviculturist, B.C. Ministry of ForestsSmithers, BC

Jen MoranB.C. Ministry of ForestsSmithers, BC

Adrian de Groot, R.P.Bio.Drosera Ecological ConsultingSmithers, BC

© 2005 Province of British Columbia

When using information from this or any Forest Science Program report,

please cite fully and correctly.

Citation:

Banner, A., P. LePage, J. Moran and A. de Groot (editors). 2005. The HyP3 Project: pat-

tern, process, and productivity in hypermaritime forests of coastal British Columbia –

a synthesis of 7-year results. B.C. Min. For., Res. Br., Victoria, B.C. Spec. Rep. 10.

<http://www.for.gov.bc.ca/hfd/pubs/Docs/Srs/Srs10.htm>

The use of trade, firm, or corporation names in this publication is for the information and convenience

of the reader. Such use does not constitute an official endorsement or approval by the Government of

British Columbia of any product or service to the exclusion of any others that may also be suitable.

Contents of this report are presented as information only. Funding assistance does not imply endorse-

ment of any statements or information contained herein by the Government of British Columbia.

http://www.for.gov.bc.ca/hfd/pubs/Docs/Srs/Srs10.htm

http://www.crownpub.bc.ca

http://www.for.gov.bc.ca/hfd/pubs/index.htm

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CONTRIBUTING AUTHORS

British Columbia Ministry of ForestsAllen Banner (project leader), Marty Kranabetter, Phil LePage, Dave Maloney, Karen McKeown, Jen Moran, Jim Pojar1

University of WaterlooRamon Aravena, Taro Asada, Lisa Emili,Dan Fitzgerald, Chris Gainham, John Gibson, Sandra Lortie, Jonathan Price, Barry Warner

ConsultantsShauna Bennett (Bio Logic Consulting),Davide Cuzner (Viking EcosystemConsultants), Adrian de Groot (DroseraEcological Consulting), Colleen Jones(Shamaya Consulting)

1 Now affiliated with the Canadian Parks and Wilderness Society, Whitehorse, Yukon.

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The HyP3 Project (pronounced “hipcubed”) was initiated in 1997 to providean integrated research approach to thestudy of pattern, process, and productivityin the hypermaritime forests of northcoastal British Columbia. The project hasfour main goals:• Document the ecology of the blanket

bog–upland forest complex of northcoastal British Columbia.

• Assess the feasibility of managing poor-and low-productivity cedar–hemlockforests, which dominate the outercoastal landscape, for timber and fibreproduction.

• Define the extent of these sites andidentify the potentially operable por-tion.

• Develop ecologically based manage-ment guidelines for these forests.The need for this research was made

clear in the 1995 timber supply review forthe North Coast Timber Supply Area.This report stated that the Chief Foresterrequired better scientific informationbefore he would consider expanding theoperable land base into lower-productivitycedar-dominated (western redcedar [Thujaplicata] and yellow-cedar [Chamaecyparisnootkatensis]) forests. Research was re-quired that would address basic ecosystemfunction (e.g., watershed and soil hydrolo-gy, plant and soil ecology, succession andstand dynamics) and provide practicalmanagement guidelines for these foresttypes.

This report presents a synthesis of theHyP3 Project’s 7-year results. It providesan overview of the project to date andsummarizes initial results for each of theproject components—hydrology and bio-geochemistry, ecosystem processes, classi-fication and inventory, and operationaltrials. The report concludes with a chapteron management interpretations.

Chapters 1 and 2 provide the back-ground to the research, including a reviewof previous studies. These chapters alsopresent descriptions of the north coastlandscape and the specific study areas,stand types, and ecosystems targeted forthe research. The geographic scope of theproject encompasses the Coastal WesternHemlock zone, Very Wet Hypermaritimesubzone, Central variant (CWHvh2) with-in the North Coast and North Island–Central Coast forest districts of the CoastForest Region. The blanket bog–uplandforest complex of the CWHvh2 containsapproximately 235 000 ha of lower-pro-ductivity cedar-dominated stands thatstraddle the defined operability thresholdsfor height class, merchantable volume,and site limitations. As market values forredcedar and yellow-cedar improve, pres-sure increases to alter the operabilitythresholds. This has already begun tooccur on the north coast, and because thisresearch is now under way, preliminarymanagement guidelines can be in placebefore operability pressures increase dra-matically. From an ecological perspective,the outer coast of British Columbia is afascinating landscape and a major thrustof the research is simply to gain a betterecological understanding of these hyper-maritime forests and wetlands.

Chapter 3 describes studies of site andwatershed hydrology and biogeochem-istry. Water plays a pivotal role in shapingecosystem function on the outer coast,and thus hydrological studies are animportant part of the HyP3 Project. Toproduce water budgets for small water-sheds and predict the potential effects oftimber harvesting on these water budgets,watershed-level studies included moni-toring of precipitation, interception,throughfall, and streamflow. Site-levelstudies examined water table dynamics,

EXECUTIVE SUMMARY

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hydrological linkages between sites, andnatural soil drainage mechanisms such assoil pipes. Soil water chemistry across thespectrum of forest and bog ecosystems inthe CWHvh2 is also characterized.

Hypermaritime watersheds of theCWHvh2 have a relatively low water stor-age capacity. The shallow, dominantlyorganic, soils typical of these watershedshave high water retention capacity, andare frequently saturated in this wet cli-mate. The small amount of available waterstorage capacity in these soils means thatsignificant runoff is generated from rela-tively small storms. Compared with otherlocations, rainfall events in the CWHvh2produce a larger hydrological response.

The decrease in canopy interceptionafter harvesting increases the amount ofwater received on the ground. At the HyP3 study sites, the canopy intercepted20–25% of the average annual rainfall. Ifthese areas are clear-cut, the amount ofwater requiring removal by existinghydrological processes can be expected toincrease. The possible hydrological conse-quences of these increased water inputsinclude faster development and increasedvolume of peak flows, higher water tables,and increased erosion resulting fromoverland flow.

Organic soils (especially on disturbedsites) have high water retention and lowcohesion qualities, and therefore the pos-sibility of increased erosion must be con-sidered. The relatively gentle slopes onwhich these low-productivity forestsoccur, however, will result in lower sur-face water runoff velocities, and thuslower off-site sediment transport than onsteeper hillslopes. Using the currentwatershed assessment procedures for roadbuilding and bridge engineering, the man-agement of additional water to a drainagesystem is possible. By knowing the har-vested area and the watershed’s dischargecharacteristics, the potential increase inpeak flows can be identified and account-ed for in management plans.

Hydrological dynamics differ amongforest types. Our study indicates that thecedar-dominated upland scrub forests(i.e., the target stands of the HyP3 Project;CWHvh2/01 sites) will likely have an on-site hydrological response to harvestingthat is intermediate between the wetterswamp forests and the more productiveupland forests. Water tables are likely torise slightly depending on specific site andsoil characteristics. Compared with theupland scrub forests, the true swampforests are quite restricted in distributionon the coast. The swamps are more sensi-tive to harvesting-induced hydrologicalchanges than upland forests; they shouldnot be harvested because of their impor-tance in receiving water and regulatingstreamflow within a watershed, and theirgreater potential for rising water tables. Where scrub forests occur on flat or verygently sloping sites, a rise in the watertable following timber harvesting isexpected and could have negative ecologi-cal implications. Smaller rainfall eventswould saturate these forest soils becauseof the reduced interception and transpira-tion following canopy removal. This mayhamper regeneration and promote paludi-fication, with the invasion of sphagnummosses and other wetland plants. Asforests regenerate, canopy interceptionand transpiration begin to increase again,but the time required for hydrologicalrecovery is still uncertain in this hyper-maritime environment. Long-term moni-toring of current and future operationaltrials will help answer this question.

High water tables and high levels ofacidity limit nutrient availability byrestricting rooting depth and maintaininganaerobic soil conditions that prevent theoxidization of nutrients to availableforms. Our study shows that the highestion concentrations in soil water occur inwell-drained (productive forest) vegeta-tion types, which have deeper water tablesand thicker aerobic zones.

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Naturally formed soil pipes play animportant role in draining forests in thehypermaritime north coast. Soil pipestransport stormflow rapidly and efficient-ly; however, if harvesting damages thesepipes, they could become “short-circuited,”decreasing their capacity to route storm-flow through the landscape.

After harvesting, dissolved organic car-bon () levels could increase alongwith the greater water inputs to a site. If increases a large amount after har-vesting, water quality can be affected.Some evidence from southeast Alaska suggests, however, that peatland streamsare better adapted to handle an increase of after harvest than the non-peat-land systems. The non-peatland systemsare thus more susceptible to changes instream biology resulting from increased inputs after harvest. Future opera-tional trials in lower-productivity westernredcedar–hemlock forests should includea soil water monitoring program. Such aprogram could better quantify changes inwater table levels and and ion con-centrations in soil and stream waters asso-ciated with harvesting.

Chapter 4 describes studies of ecosys-tem processes, including disturbance andecological succession, vegetation dynam-ics, production and decomposition, nut-rient cycling, and other aspects of soilecology. Organic matter dynamics,including rates of forest humus and peataccumulation, is an important ecosystemprocess on the outer coast, where organicsoil layers play a vital role in determiningsuccessional trends and site productivity.

The many peatlands that characterizethe coastal landscape preserve a record ofpast conditions in their pollen and macro-fossil profiles. These profiles provide thedata against which we can compare cur-rent conditions, and predict future hydro-logical and related ecosystem responses tonatural and human-influenced disturbances.Core sampling at several sites was con-ducted to reconstruct historical vegetationpatterns and rates of peat accumulation.

Production and decomposition rates with-in present-day vascular plant and mosscommunities were measured to estimatecurrent rates of accumulation. These stud-ies included detailed measurements ofannual sphagnum moss productivity andcolonization on both disturbed and undis-turbed sites.

HyP3 research also included studies ofbedrock, soil property, and site productiv-ity relationships in both old-growth andsecond-growth stands across the spectrumof site series, from bog woodland andscrub forest to productive upland forest.

From these ecosystem process studies, a simple model of ecosystem developmentin the CWHvh2 has emerged. In this model,three main factors operate in combinationto drive ecosystem development and pro-ductivity in this hypermaritime environ-ment:1. bedrock geology2. soil drainage3. disturbance history

Although these same factors influenceecosystem development to some degree inmost other terrestrial environments, theirinfluence is especially dramatic in theCWHvh2.

The scarcity of glacial till in this coastalenvironment highlights the importance ofbedrock geology. Most soils develop direct-ly from the weathering of bedrock or col-luvial material. This contrasts with manyother areas where a mantle of glacial till of mixed lithology masks the influence ofbedrock. In addition, sharp contrasts inbedrock type occur on the outer coast,from the hard, slowly weathering grano-diorites with relatively low amounts ofavailable nutrient elements, to the muchsofter, easily weathered metamorphicrocks and limestone with more nutrient-rich lithologies. These different bedrocktypes manifest themselves in dramatic dif-ferences in plant communities and forestproductivity.

Excess soil water is the rule in thishypermaritime environment, and subtlevariations in slope or internal soil

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drainage result in significant differences in forest productivity. In contrast to the majority of other subzones in theprovince (where moisture deficits arecommon), the most freely drained sites in the CWHvh2 are the most productivesites for trees. Even these “drier” sites arefresh to moist in absolute terms, and aslong as soil water is moving, rather thanstagnant, tree productivity will remainmoderate to high.

The tendency for organic matter toaccumulate on sites that have not beendisturbed by landslides, windthrow, orfluvial disturbances for hundreds (orthousands) of years is also dramatic in the CWHvh2. As soil organic matter accu-mulates, soils become wetter and treeroots become more confined to surfaceorganic horizons. Although the nutrientcapital in these organic horizons is consid-erable, nutrient availability is relativelylow because of the wet, acidic conditionsand low rates of nitrogen mineralization.Better-drained sites, which often have ahistory of natural disturbance, especiallywhere soil organic and mineral horizonsare mixed, exhibit higher forest produc-tivity.

Although models are inherently sim-plistic, ecosystem development and forestproductivity on the majority of sites onthe outer coast are largely driven bybedrock geology, soil drainage, and dis-turbance history working in combination.The model presented in Chapter 4 canalso be used to guide forest managementinvestments and activities, and to helpdefine and understand the limits of oper-ability in the CWHvh2. For example, marginally productive sites occurring onmetamorphic rock will exhibit higher sec-ond-growth productivity following har-vesting and site treatments compared with a similar site on granodiorites.

Two variations of the model are pre-sented—one emphasizing forest produc-tivity, and one emphasizing biomassallocation. As indicated by the soil ecolo-gy, moss productivity, and succession

studies, a switch in biomass allocationfrom trees to mosses (and other under-storey vegetation) occurs as sites paludifyand tree productivity declines. Bogs andbog forests are often referred to as “lowproductivity.” They are, however, highlyproductive if one considers the annualrates of total biomass accumulation inthese ecosystems.

Chapter 5 presents the classificationand inventory component of the HyP3

Project, which serves as the link betweenthe hydrology and ecosystem processcomponents and the application of resultsacross the north coast. The project hasused the Biogeoclimatic EcosystemClassification () system as the frame-work to make ecologically based forestmanagement recommendations. usesthe site series to classify forests for man-agement purposes. Ecosystem classifica-tion is invaluable for choosing appropriatesites for in-depth studies, and for extrapo-lating the results to other similar sites onthe north coast.

We conducted sampling to collectbaseline information on tree growth andsite productivity throughout the range offorested site series in the CWHvh2. Thesedata show that estimates of site productiv-ity from old-growth stands significantlyunderestimate second-growth site poten-tial. On CWHvh2/01 (upland scrub forest)sites, for example, western redcedar siteindex at breast height age 50 years, aver-ages 18 m in second-growth stands, butestimates of 10 m or less are derived fromold-growth stands. Past timber supplyanalyses have used the old-growth pro-ductivity estimates from the forest coverinventory database to model the growthand yield of regenerating stands. This sug-gests that potential yields of second-growthCWHvh2/01 sites, as well as other current-ly operable sites, are underestimated. HyP3

results clearly indicate that second-growthproductivity of these scrub forests is highenough to consider them as potentiallyoperable, subject to the assessment ofother site limitations.

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At each of the HyP3 study sites, timbercruising was carried out to quantify standstructure, species composition, and grossand merchantable volume. Several forestmensuration attributes are summarizedfrom these data for each of the CWHvh2site series studied. Rare, or otherwisethreatened or imperiled ecosystems of theCWHvh2 are also reviewed to examine the potential effects of expanding forestryoperations into the lower productivityforest types.

A predictive ecosystem mapping ()model was developed for the outer coast.The resulting maps identify the site seriesmost likely associated with each forestcover polygon. These maps help to estab-lish the extent and location of potentiallyoperable low-productivity cedar–hemlockforest types. Site series productivity datacan also be combined with these maps toaid in growth and yield analysis.

Chapter 6 describes the HyP3 opera-tional research trials at Port Simpson andOona River. The trial near Port Simpson,north of Prince Rupert, was established in1990 to examine second-growth produc-tivity in the poor cedar–hemlock foresttype. Initially funded by South MoresbyForest Replacement Account ()research funds, this study was taken overby the HyP3 Project in 1999. The PortSimpson trial focused on the effect ofmounding on the survival and growth ofplanted seedlings and on some of the eco-logical impacts of site treatments. TheOona River operational trial is located onPorcher Island, south of Prince Rupert.This is a more expansive trial and wasestablished in 1998 to test some of themanagement ideas gained from both the Port Simpson trial and the multi-tude of research studies undertaken onCWHvh2/01 sites around Prince Rupert.The Oona River trial examines severalecological and operational aspects of for-est management activities on the low-productivity cedar–hemlock sites.

Results from the Port Simpson trialsuggest that site preparation, including

soil mixing and mounding, improvesregeneration success and tree growth andnutrition on poor cedar–hemlock sites.Care must be taken, however, to avoidcreating conditions (e.g., pools besidemounds) that facilitate sphagnum mossgrowth and paludification. Monitoring ofplanted and natural regeneration, as wellas moss and vascular plant succession, atthis site will continue into the future.Block layout, harvesting, site treatments,planting, and initial regeneration surveysare complete at the Oona River trial.Planted western redcedar survival andgrowth results are very encouraging andreinforce the belief that CWHvh2/01 siteshave significant forest managementpotential. Long-term monitoring of thistrial will take place to ensure that earlytrends continue and management inter-pretations remain current and realistic.

Chapter 7 presents management inter-pretations resulting from the first 7 yearsof HyP3 research and operational trials.The HyP3 Project focuses primarily on theecological and operational feasibility ofsustainable forest management practiceson the CWHvh2/01 sites. The economicsof the operations were not examinedbecause the value of western redcedar isquite variable, and subtle changes will sig-nificantly affect the economic viability ofmanaging these sites.

Low-productivity sites in the CWHvh2belong primarily to the Western redcedar– Western hemlock – Salal site series(CWHvh2 /01). These sites typically havebetween 200 and 300 m3/ha merchantablevolume. The vast majority of these sitesare currently outside the operable landbase. At the upper end of the productivityspectrum for these site series, soil and veg-etation conditions become transitional tothe Western hemlock – Sitka spruce –Lanky moss site series (CWHvh2/04),which is currently included in the opera-ble land base (merchantable volumes typi-cally greater than 400 m3/ha). At thelower extremes of productivity for theCWHvh2/01 site series, conditions are

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transitional to the Western redcedar –Yellow-cedar – Goldthread site series(CWHvh2/11), in which merchantablewood volumes (typically less than 150 m3/ha) are well below current and projected operability limits.

Historical ecosystem classification datawere used to develop better descriptionsof these hypermaritime ecosystems, espe-cially for the lower-productivity foresttypes of interest in this study. By combin-ing this information with HyP3 Projectresults, we have defined a set of criteria toidentify those CWHvh2/01 sites with thegreatest potential for sustainable forestmanagement. These criteria include:depth and nature of mineral and organic

soil horizons, bedrock geology, overstoreyand understorey composition, and standvolume. Other information, such as loca-tion and access, should be used in combi-nation with these site factors to determineoverall operability on a site-specific basis.We will further refine these operabilitycriteria as we gain more experience inthese forest types.

Specific recommendations are providedon block layout, harvesting methods, sitepreparation treatments, and planting onCWHvh2/01 sites. Chapter 7 concludeswith a summary of the future researchrequired to further develop and test ourcurrent management recommendationsfor these hypermaritime ecosystems.

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As the list of contributing authors indi-cates, the success of HyP3 Project and theproduction of this synthesis report result-ed from the dedicated, co-operative workof many individuals over the past 8 years.The compilers and editors are greatlyindebted to all of the contributing authorswho co-ordinated and carried out specificcomponents of the HyP3 Project and con-tributed to various chapters of this report.In addition, the following individualsplayed important roles in various stages of the field work, logistics, data analysis,and final reporting.

Colleen Jones provided organizationaland administrative support during theearly years of the project. Gordon Kayaharaand Christine Chourmouzis co-ordinatedand carried out the stand reconstructionstudies in the early years of HyP3. PatrickWilliston and Karen Golinski planned andconducted the assessment of lichen andbryophyte diversity at the Oona River trialsite. Over the duration of the project, fieldassistance was provided on various studycomponents by: Shauna Bennett, BruceCatton, Dave Coates, Danielle Cobbert,Leah Cuthbert, Pauline Favero, KarenGeertsema, Sarah Graham, Marcel Lavigne,Will MacKenzie, Michelle McGibbon, Rob Meisner, Kelli Ohland, Penny Olanski,Mike Oiser, Larissa Puls, Dave Redman,Dave Spittlehouse, Victoria Stevens,Sandra Thomson, Ted Turner, SheilaVardy, Dave Wilford, Alex Woods, ColinWoolridge, Elaine Wright, and Tara Wylie.These individuals all contributed to thesuccess of the project.

We thank the Lax Kw’alaams Band fortheir co-operation in establishing the PortSimpson operational trial, and Sally andWilfred Knott and their family for thewonderful hospitality during our stays atthe village.

Thanks also go to Tony Duggleby,Herb Pond, and the staff at the North

Pacific Cannery, our field headquartersfor the early years of the study. The staffat the North Coast Forest District, espe-cially Mike Grainger, Marc Bossé, andCzeslaw Koziol, are recognized for theirlogistical support. Davide Cuzner, former-ly with the North Coast Forest District,was a key member of the HyP3 team fromits inception, and co-ordinated or assistedwith many aspects of the project. Hisunending enthusiasm for the work was aninspiration for everyone. Karen McKeownhas been, for many years, the “glue” thatholds our Forest Service research team inSmithers together and her positive out-look and willing assistance with all aspectsof this project are greatly appreciated.

The establishment of our operationaltrial at Oona River would not have beenpossible without the dedication and assis-tance of many members of the extendedBergman family. At Oona River, we wereafforded an excellent opportunity to meldscience with operations, and the keen par-ticipation and assistance of the Bergmansmade this opportunity a reality. Theirexpertise, diverse local knowledge, andhistorical perspective were invaluable tothe success of the project. To Johnny,Karl, David, their families, and the manyother Oona River residents that helpedmake our field studies there rewarding,fun, and fattening, we extend our sincerethanks.

Technical reviews of this report werekindly provided by Bernard Bormann,Geoff Cushon, David D’Amore, MikeGrainger, Paul Hennon, Paul Marquis,Del Meidinger, Peter Ott, Chuck Rowan,and Larry Sigurdson, and we thank themfor their helpful suggestions. English edit-ing and proofreading was carried out bySusan Bannerman, and typesetting andpage layout by Donna Lindenberg. We are grateful to Paul Nystedt and theProduction Resources staff of the B.C.

ACKNOWLEDGEMENTS

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Ministry of Forests, Research Branch, inVictoria for co-ordinating the publicationof this report.

Forest Renewal BC provided fundingfor the first 5 years of this project. Morerecently, funding was provided by theProvince of British Columbia ForestInvestment Account, through the cooper-ation of International Forest Products

Ltd., Interpac Resources Ltd., andTriumph Timber Ltd., and the B.C.Ministry of Forests, Coast Forest Region.We thank Denis Collins, ResearchManager, Coast Forest Region, for hisassistance in obtaining funding to supportthe continuation and publication of thisresearch.

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Contributing Authors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 The Issue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 HyP3 Research Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.3 Previous Studies: Historical Perspective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2 Location and Environmental Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.1 Location, Physiography, and Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.2 Climate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.3 Vegetation, Soils, and Ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.4 Natural Disturbance Regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.5 Adjacent Biogeoclimatic Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162.6 HyP3 Study Sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3 Hydrology and Biogeochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.2 Watershed Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.3 Soil Hydrology and Biogeochemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293.4 Discussion and Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

4 Ecosystem Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474.2 Succession and Disturbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474.3 Paludification and Vegetation Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514.4 Vegetation Types and their Dynamics: Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664.5 Soil Ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 684.6 Model of Ecosystem Development and Productivity in the CWHvh2. . . . . . . . . . . 80

5 Classification and Inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825.1 Introduction and Approach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825.2 Site Series Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 825.3 Site Productivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 865.4 Forest Mensuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 895.5 Biodiversity Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 945.6 Predictive Ecosystem Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

6 Operational Research Trials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1056.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1056.2 Port Simpson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1056.3 Oona River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

7 Management Interpretations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1187.1 Identification of Potentially Operable Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1187.2 Silvicultural Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1187.3 Future Research Direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

CONTENTS

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Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

1 HyP3 Project-related Extension Notes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

2.1 Climatic data for the CWHvh2 and some adjacent subzones. . . . . . . . . . . . . . . . . . . . . . . 123.1 Total monthly rainfall by site and elevation, correlated to the

North Pacific Cannery reference site at Port Edward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.2 Percentage of rainfall by wind direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.3 Annual rainfall, throughfall, stemflow, and interception at the Smith

Island and Diana Lake sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.4 Maximum and minimum monthly interception as a percentage

of rainfall at the Smith Island and Diana Lake sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.5 Rainfall interception sorted by canopy condition, event intensity,

and event length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.6 Production of stemflow by tree size class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283.7 Water balance for the Smith Island and Diana Lake watersheds, 1998–2001. . . . . . . 283.8 Average depth to water table, pH, and dissolved organic carbon of

groundwater from mineral and organic soil horizons by site series . . . . . . . . . . . . . . . . 313.9 Characteristics of the S01 and K-pipe basins. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343.10 Mean ionic composition of groundwater by site series at Diana

Lake, 1997–1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.11 Mean ionic composition of groundwater in the organic and mineral

subsoil horizons at Diana Lake, 1997–1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.12 Mean seasonal ionic composition of groundwater at Diana Lake,

1997–1998. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404.1 Growth and production of sphagnum and other mosses and their

correlation with climatic parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 524.2 Vegetation classified at the Diana Lake study site by two-way

indicator species analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554.3 Vegetation classified at the Port Simpson study site by two-way

indicator species analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594.4 Estimated total net primary production for the five representative

micro-communities in the open bog at the Diana Lake study site . . . . . . . . . . . . . . . . . 654.5 Mass loss of Sphagnum fuscum litter from litter bags incubated at

10 cm below ground surface for 1 year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 654.6 Total chemical concentrations for bedrock types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 694.7 Mean organic and mineral soil depths for CWHvh2 site series

on the north and central coast of British Columbia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704.8 Mean organic and mineral soil depths for CWHvh2/01 and CWHvh2/04 site

series by bedrock type on the north and central coast of British Columbia . . . . . . . 704.9 Average chemical properties of mineral soils, well-drained sites only . . . . . . . . . . . . . 704.10 Foliar nutrient concentrations for western hemlock, Sitka spruce, and

western redcedar on productive sites of north coast British Columbia . . . . . . . . . . . . 78

4.11 Average height increment for each tree species by soil moisture regime and bedrock type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

5.1 Old-growth and second-growth productivity data for the CWHvh2, north coast of British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

5.2 Summary of average stand characteristics for the CWHvh2/11, /01, and /04 site series at the Diana Lake, Oona River, and Smith Island study areas. . . . . . . . . . . 89

5.3 Tree heights used for height class designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 935.4 Summary of average stand characteristics for the CWHvh2/11 site

series at the three study sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 935.5 Summary of average stand characteristics for the CWHvh2/01 site series

at the three study sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 935.6 Summary of stand characteristics for the CWHvh2/04 site series at the

three study sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 945.7 Red- and blue-listed ecosystems of the hypermaritime mainland coast

of British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 955.8 A comparison of foliicolous lichens and bryophytes from Porcher Island

and those reported by Vitt et al. (1973) from other coastal localities in British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

6.1 Substrate descriptions at Port Simpson mounding trial . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1066.2 Average percent survival and height of planted western redcedar seedlings

at Oona River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1156.3 Cruised and call-graded merchantable timber volumes by log grade

and species from the Oona River operational research trial . . . . . . . . . . . . . . . . . . . . . . . . 1167.1 Site identification criteria for determining operability of Western redcedar –

Western hemlock – Salal (01) sites CWHvh2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

1.1 North Coast Timber Supply Area, British Columbia, Canada. . . . . . . . . . . . . . . . . . . . . . 21.2 Harvested sites on highly productive steep slopes of the

CWHvh2 subzone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 Distribution of the CWHvh2 within the North Coast Forest District. . . . . . . . . . . . . . 31.4 Landslide associated with mid-1980s road-building activities, coastal

British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.1 Generalized bedrock geology, central and north coast of British Columbia . . . . . . . 112.2 Upland productive forest type, CWHvh2/06 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.3 Upland scrub forest type, CWHvh2/01. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.4 Bog forest type, CWHvh2/11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.5 Bog woodland forest type, CWHvh2/12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.6 Blanket bog, CWHvh2/32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.7 Edatopic grid depicting forested site series of the CWHvh2 subzone . . . . . . . . . . . . . . 142.8 Open bog development on 2 m of accumulated peat near Prince Rupert . . . . . . . . . 152.9 Location of HyP3 intensive study sites and operational trial sites on the

north coast of British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.1 Trough system used to collect rain “throughfall” data at the Diana Lake

study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.2 Stemflow collection system on a redcedar tree at the Smith Island study site . . . . . 21

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3.3 V-notch weir for measuring discharge on a bog stream at the Diana Lake study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.4 Hydrological response and lag time for small and large rainfall events in the Smith and Diana watersheds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.5 Frequency distribution of rainfall events greater than 1 mm at the Diana Lake study site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

3.6 Percent of total rainfall by event size category at the Diana Lake study site . . . . . . . 243.7 Interception as a percentage of rainfall, by rainfall event, at the

Diana Lake and Smith Island sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.8 Conceptual model of discontinuous soil pipes forming linkages with

localized dynamic contributing area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293.9 Model of groundwater flowpaths in zonal forests and open bogs in

the Smith Island watershed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323.10 Examples of soil pipes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333.11 Comparison of typical storm hydrograph response between the

K-pipe and S01 basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363.12 Selected storm recession graphs for the K-pipe and S01 basins during

the 2000 field season . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373.13 Relationship between the S01 basin and K-pipe basin dynamic

contributing areas and 10-day antecedent rain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373.14 Hydrological parameters measured in a bog at the Diana Lake study site . . . . . . . . . 383.15 Dissolved organic carbon concentrations, rainfall, and stream discharge,

Smith Island watershed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414.1 Historical climatic conditions on the north coast relative to present

conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494.2 Canonical correspondence analysis of Diana Lake study plots . . . . . . . . . . . . . . . . . . . . 584.3 Depressions created by mounding at Port Simpson filled in with

sphagnum moss after 6 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604.4 Growth patterns of Pleurozium schreberi in relation to climatic parameters

for eight consecutive sampling intervals from June 1999 to July 2000 . . . . . . . . . . . . . 624.5 Growth patterns of four Sphagnum species in relation to climatic

parameters for eight consecutive sampling intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 634.6 Change in cover of Sphagnum girgensohnii between 1998 and 1999 at

one of the three Port Simpson sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 644.7 Four common bedrock types found on the north and central coast

of British Columbia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 684.8 Comparisons of microbial respiration rates and chemical properties. . . . . . . . . . . . . . 724.9 Comparisons of microbial respiration rates and moisture content . . . . . . . . . . . . . . . . 734.10 Changes in C:N and C:P ratios across CWHvh2 site series in old-growth

and second-growth stands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 734.11 Western hemlock nutrient concentrations for current-year needles and

1-year-old needles across height increment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 754.12 Sitka spruce foliar nutrient concentrations for current-year needles and

1-year-old needles across height increment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 764.13 Western redcedar foliar nutrient concentrations for current-year needles

and older needles across height increment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 774.14 Simplified model of ecosystem development and forest productivity in

the CWHvh2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

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5.1 Zonal forest (CWHvh2/01), Oona River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 835.2 Bog forest (CWHvh2/11), Diana Lake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 835.3 Bog woodland (CWHvh2/12), Diana Lake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 845.4 Open bog (CWHvh2/32), Diana Lake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 845.5 Productive upland forest (CWHvh2/06), Port Edward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855.6 Productive spruce stand on a CWHvh2/08 site, Barnard Creek,

Princess Royal Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855.7 Swamp forest (CWHvh2/13), Diana Lake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 865.8 Dry, windswept rock outcrop (CWHvh2/02), McCauley Island . . . . . . . . . . . . . . . . . . . 865.9 Second-growth CWHvh2 stand used for site index sampling, Khyex River . . . . . . . 875.10 Net merchantable volume per hectare by site series and species at

the Diana Lake, Oona River, and Smith Island study sites. . . . . . . . . . . . . . . . . . . . . . . . . . 905.11 Stems per hectare by site series and species at the Diana Lake,

Oona River, and Smith Island study sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 905.12 Basal area and stems per hectare in diameter classes at the Diana Lake,

Oona River, and Smith Island study sites by site series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915.13 Stems per hectare in height classes by site series at all sites and by species

at the Diana Lake, Oona River, and Smith Island study sites . . . . . . . . . . . . . . . . . . . . . . . 925.14 Productive yellow-cedar stand on Mount Genevieve,

Haida Gwaii/Queen Charlotte Islands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 965.15 Productive Sitka spruce–western redcedar forest on limestone

bedrock, Hamner Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 975.16 Kerouard Islands, south of Kunghit Island, Haida Gwaii/Queen

Charlotte Islands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 985.17 Tidal estuary, Kwatna Inlet, east of Burke Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 985.18 Sandy beach on the west side of Calvert Island. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 995.19 Carex sitchensis fen near Prudhomme Lake, Prince Rupert. . . . . . . . . . . . . . . . . . . . . . . . . 1005.20 The predictive ecosystem mapping procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1025.21 The EcoGen predictive ecosystem mapping approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1036.1 Port Simpson mounding trials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1066.2 Mean height and mean caliper of western redcedar, western hemlock,

and shore pine 5 years after planting on mounded and unmounded plots at the Port Simpson study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

6.3 Root and shoot biomass of western redcedar, western hemlock, and shore pine 6 years after planting on mounded and unmounded plots at the Port Simpson study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

6.4 Rooting characteristics of western redcedar, western hemlock, and shore pine 6 years after planting on mounded and unmounded plots at the Port Simpson study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

6.5 Root development of western redcedar growing on unmounded and mounded plots 6 years after planting at the Port Simpson study site . . . . . . . . . . . . . . 108

6.6 Nitrogen content of pine needles from trees growing on five substrate types at the Port Simpson study site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

6.7 Macronutrient content of pine needles from trees growing on five substrate types at the Port Simpson study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

6.8 Ecosystem map of Oona River study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1106.9 Block 1 at the Oona River study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

xvii

6.10 Excavator “hoe-chucking” logs to main skid trail at the Oona River study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

6.11 tracked skidder moving logs to the landing at the Oona River study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

6.12 Excavator raking and piling slash in block 1 at the Oona River study site . . . . . . . . . 1126.13 Mixed mineral and organic mound on a CWHvh2/01 site at the Oona

River study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1126.14 Seedling protectors tested at the Oona River study site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1136.15 Western redcedar sample tree marked for stem-analysis cutting. . . . . . . . . . . . . . . . . . . 1146.16 Aerial view of block 1 at Oona River showing the irregular ecosystem-

based boundaries and the individual and patch leave trees . . . . . . . . . . . . . . . . . . . . . . . . . 1156.17 Some redcedar siding and dimensional lumber produced at the Group

Mills operation at Oona River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

1

The HyP3 Project (pronounced “hipcubed”) provides an integrated researchapproach to the study of pattern, process,and productivity in the hypermaritimeforests of north coastal British Columbia.Initiated in the North Coast ForestDistrict in 1997, this project aims to devel-op ecologically based guidelines for themanagement of cedar-dominated forests,most of which are outside the currentoperable land base. Lower-productivitycedar–hemlock forests that containsignificant amounts of timber, includinghigh-value western redcedar2 (Thuja plica-ta) and yellow-cedar (Chamaecyparisnootkatensis), dominate much of the outercoastal landscape; however, considerableuncertainty surrounds the feasibility andsustainability of harvesting these wet,slow-growing forests.

HyP3 researchers are using basic studies of ecosystem structure and func-tion, as well as operational trials, toaddress the following project goals:

• Document the ecology of the blanketbog–upland forest complex of northcoastal British Columbia.

• Assess the feasibility of managing poor-and low-productivity cedar–hemlockforests for timber and fibre production.

• Define the extent of these sites andidentify the potentially operable por-tion.

• Develop ecologically based manage-ment guidelines for these forests.This report presents a synthesis of the

HyP3 Project’s 7-year results. It providesan overview of the project to date andsummarizes initial results for each of theproject components—hydrology and bio-geochemistry, ecosystem processes, clas-sification and inventory, and operationaltrials. The report concludes with a chapteron management interpretations. A glos-sary is also included to define the techni-cal terms used in the text.3

1 INTRODUCTION

2 Nomenclature for scientific and common names of vascular and non-vascular plants follows Meidinger et al. (2004).

3 Technical terms included in the glossary appear in boldface at first mention.

4 The boundary of the North Coast was recently modified and thus the breakdown of the land base provided here has been altered slightly. The area of the currently totals 1.88 million ha.

The North Coast Timber Supply Area(), within the Coast Forest Region(formerly within the Prince Rupert ForestRegion), encompasses 1.95 million haalong the British Columbia coast, extend-ing from Princess Royal Island to south-east Alaska (Figure 1.1). Although 39%(758 788 ha) of the is considered pro-ductive forest land, only 6% (119 130 ha) is currently included within the operable(timber harvesting) land base because oflimitations associated with environmentalconcerns, accessibility, and timber sizeand quality (British Columbia Ministry ofForests 1999).4

The effects of hand-logging and A-frame operations, which began at the turnof the 20th century, and the larger indus-trial operations of today, are readilyapparent along the north coast. Harvestingwas restricted primarily to the highly pro-ductive steep slopes (often adjacent totidewater) and alluvial valley bottoms(Figure 1.2). These locations yielded thehighest volumes per hectare and the great-est return on investment for the relativelycostly coastal timber harvesting opera-tions. Harvesting of some species, such asSitka spruce (Picea sitchensis) and amabilisfir (Abies amabilis), was disproportionately

1.1 The Issue

2

high compared with their percentage ofthe standing volume. Very little harvest-ing has occurred in the lower productivityheight class 2 and 3 (< 30 m tall) cedar–hemlock stands typical of the gentlernorth coast terrain. These stands make up 12% of the (roughly 235 000 ha),and contain significant quantities of bothwestern redcedar and yellow-cedar. Thesetwo species often grow together with low-quality western hemlock (Tsuga heterophylla) and mountain hemlock (T. mertensiana), and lesser amounts ofshore pine (Pinus contorta var. contorta).Most of these stands are currently exclud-ed from the operable land base because of their low volume (as determined byinventory height class). As the marketvalue of western redcedar and yellow-cedar increases, so does the attractivenessof these stands for harvesting.

The current allowable annual cut() for the North Coast Forest Districtis 573 624 m3.5 This cut is projected todecline in about 20 years (the so-called“falldown” effect) as we shift from cuttingold-growth forests to lower-volume sec-ond growth. A long-term harvest rate of361 000 m3 is predicted by the year 2060(Pedersen 2001). Harvesting in areas thatare now considered inoperable may offsetreductions in the , or reduce harvest-ing pressure in the existing operable landbase. Before this potential expansion ofthe operable area can occur, however,concerns about sustainability must beaddressed and satisfactorily resolved. Inhis 2001 determination, the ChiefForester stated,

If and when research results indicate thepotential to manage some of the exclud-ed stands for timber production from abiological, silvicultural regime and eco-nomic viewpoint . . . then it may beappropriate to consider some level ofcontribution from these stands in afuture timber supply review (Pedersen2001).

. North Coast Timber Supply Area, British Columbia, Canada.

. Harvested sites on highly productive steep slopes of the CWHvh2subzone.

5 The AAC has recently been reduced to 546 624 m3.

3

Thus, before any harvesting occurs,researchers must assess whether thesestands can be managed sustainably (i.e., in terms of their regenerative capacity and site productivity, and the possibleeffects on biodiversity and other non-timber resources and values). Althoughexpanding the operable land base could

theoretically permit an increase in the (by up to 120 000 m3), the Chief Forestersuggested that any expansion should beused to extend existing harvest levels fur-ther into the future, therefore maintaininga higher long-term harvest level.

In response to the Chief Forester’s ini-tial request for research in his 1995 determination (Pedersen 1995) for theNorth Coast , Ministry of Forests staff in the (then) Prince Rupert ForestRegion commissioned a problem analysis(Kayahara and Klinka 1997). A proposalwas then submitted to Forest Renewal BCthat outlined plans to carry out researchand to develop ecologically based opera-tional guidelines for timber harvesting inthe western redcedar–western hemlockforests on the outer coast. Forest RenewalBC approved funding for the project inMay 1997. The resulting HyP3 Project hasused site-specific studies and operationaltrials to better understand the area’s ecol-ogy, silviculture, and hydrology, andbroader classification and inventory stud-ies to identify the potentially operableportion of the land base.

In the problem analysis, Kayahara andKlinka (1997) also identified the higher-elevation ecosystems of the MountainHemlock (MH) biogeoclimatic zone asanother possible area of future operability,but operating in the MH zone was clearlya separate issue requiring its own study.Therefore, the HyP3 initiative was limitedto the Coastal Western Hemlock VeryWet, Hypermaritime subzone, Centralvariant (CWHvh2, Figure 1.3) and did notaddress issues of sustainable harvesting inthe MH zone.

Timber inventories usually identifylower-productivity forests on the outernorth and central coast as CwYcPl931P,6

921P, or 921L stands, and rate them as“inoperable.” The forest sites of interest

6 Codes used on forest inventory maps indicate: species (Cw = western redcedar; Yc = yellow-cedar; Pl = shorepine); age class (9 = greater than 250 years old); height class (2 = 10.5–19.4 m; 3 = 19.5–28.4 m); stocking (1 = mature, greater than 76 stems per hectare); and site class (P = poor; L = low; recently replaced by calcu-lated or estimated site index).

. Distribution of the CWHvh2 within the North Coast ForestDistrict.

4

for this research occur mainly within the CWHvh2 and typically have wet soilswith thick surface organic layers (forestfloors). Research in north coastal BritishColumbia and southeast Alaska suggeststhat productive forests can develop into bogs through a process of organic

matter accumulation over mineral soils(paludification) (Banner et al. 1983;Kayahara and Klinka 1997); therefore, theeffect of timber harvesting in promotingor combating this process, and thusinfluencing second-growth productivity, is of particular interest.

Experience in coastal British Columbia,Haida Gwaii/the Queen Charlotte Islands,and southeast Alaska has demonstratedthat timber harvesting and associatedactivities (e.g., road building; Figure 1.4)on steeper slopes increase the likelihoodof landslides, which in turn can increasethe sediment input into streams (Kayaharaand Klinka 1997). Slope stability issues are less of a concern within the lower-productivity stands on gentler terrain;however, access, road building, and forestregeneration in areas of wet, organic soilsare significant concerns. Not only does thepotential for sediment loading of streamspersist, but a host of hydrological changesmay effect root zone saturation, nutrientdynamics, and ultimately, forest produc-tivity. The nature, rate, and extent of such changes have not been documentedfor this type of environment, so theseprocesses are poorly understood. Finally,expanding the operable land base intolower-productivity stands could lead to a substantial expansion of harvested areas across the landscape and couldsignificantly affect non-timber values,such as wildlife, biodiversity, and visualquality.

. Landslide associated with mid-1980s road-building activities,coastal British Columbia.

The HyP3 Project is an integrated, multi-disciplinary study of the coastal blanketbog–upland forest complex of the CWHvh2.We are working toward developing a bet-ter understanding of these ecosystems, aswell as assessing the feasibility of harvest-ing these areas responsibly and sustainably,and providing management guidelines fordoing so. With this in mind, we used acombination of scientific studies, opera-tional trials, and inventory techniques toaddress our four project goals.

Intensive, site-specific studies havebeen carried out along two old-growthtransects located near Prince Rupert.These transects include representativeexamples of the full range of ecosystemsstudied, from productive forests to blan-ket bogs. Researchers have conductedstudies along these common transects tomaximize co-operation among disciplines.This co-operative approach has helped todevelop a better understanding of howone ecosystem component, such as

1.2 HyP3 ResearchApproach

5

hydrology, relates to others such as soilecology or site productivity.

The more extensive aspects of the studyoccur on a range of sites throughout theNorth Coast Forest District. For example,operational trials are under way at OonaRiver on Porcher Island, 40 km south ofPrince Rupert, and near Port Simpson onthe Tsimpsean Peninsula, north of PrinceRupert. Classification and inventory workis ongoing throughout the District.

The project is organized into the fol-lowing four components, which areaddressed in separate chapters of thisreport. 1. Hydrology and Biogeochemistry

(Chapter 3)• Document the watershed, soil

hydrology, and biogeochemistry of the blanket bog–upland forestcomplex.

• Predict how disturbances from forestharvesting can affect soil and water-shed hydrology, forest succession,and regeneration.

2. Ecosystem Processes (Chapter 4)• Document relationships among soil

chemical, biological, and physicalcharacteristics, and site series andtree productivity.

• Examine selected biological process-es, such as soil respiration, litterdecomposition, and organic matterdynamics (rates of forest floor andpeat accumulation; soil faunal andmicrobial activity), in relation to for-est productivity and bedrock type.

• Examine the potential for manipulat-ing soil characteristics, through harvesting and site treatments, toimprove second-growth tree produc-tivity.

• Document past and present ecologi-cal succession in the area in relation

to peat development, and determinehow this is linked to site hydrologyand geochemistry, as well as produc-tivity and ecosystem development.

3. Classification and Inventory (Chapter 5)• Describe the range of ecological site

characteristics associated with thetarget forest types, and determinetheir operational significance.

• Examine the use of PredictiveEcosystem Mapping () to identi-fy stands with the highest potentialfor timber management.

• Identify rare and sensitive compo-nents of biodiversity (species andecosystems) that could be at riskfrom forest harvesting.

• Estimate growth and productivityacross the spectrum of site series inthe CWHvh2.

• Develop baseline information on thepatterns of regeneration and growthin both old-growth and second-growth stands on low-productivitysites.

4. Operational Research Trials (Chapter 6)• Develop and implement a strategy

for testing harvesting and silvicultur-al approaches in target forest types.

• Complete the assessment of the PortSimpson mounding trial, which wasestablished in 1990.

• Establish additional operational har-vesting trials within the North Coast to better define operability limits.

Chapter 7 provides management inter-pretations for cedar–hemlock ecosystemsand outlines further research needs.

6

1.3.1 Early ecological studiesDocumented ecological studies of thebogs and forests of the west coast ofBritish Columbia go back to the early1900s (Rigg 1914, 1917, 1925, 1940; Rigg and Thompson 1922; Osvald 1933). Theseearliest studies were mostly carried out inWashington, Oregon, southwesternBritish Columbia, and southeast Alaska,and concentrated on descriptions of thevegetation, peat stratigraphy, and succes-sional relationships of non-forested bogecosystems. Williston (2003a) summarizedthe history of botanical collecting andresearch that has occurred on the northcoast since the expeditions of Franz Boasand George Dawson in the late 1800s.

1.3.2 Ecosystem classification and relatedstudies Beginning in the late 1950s, V.J.Krajina and many of his graduate studentsundertook extensive ecosystem classifi-cation studies on the west coast. Onceagain, these were mainly carried out onthe south coastal mainland and VancouverIsland (Muëller-Dombois 1959, 1965;Lesko 1961; Orloci 1961, 1964; Wade 1965;Cordes 1972; Kojima and Krajina 1975;Klinka 1976). During this time, Krajinaproposed the biogeoclimatic approach toecological zonation of the entire province,and produced the first maps of biogeocli-matic zones (Krajina 1959, 1965, 1969).Spilsbury and Smith (1947), however, car-ried out forest site classification studies inthe south coastal area of the provincebefore Krajina and his students begantheir work, and first proposed the use ofsite classification to describe site quality(forest productivity) and ensure “sus-tained yield forestry” in British Columbia.

By the mid-1970s, the biogeoclimaticecosystem classification () systemhad been adopted by the B.C. Ministry ofForests as a framework for forest manage-ment. This Ministry’s Research Branchembarked on a province-wide classific-ation program and recruited ecologists,botanists, soil scientists, and foresters tofurther develop and refine . This

included the development of tree speciesselection guidelines and other manage-ment interpretations in each of the sixforest regions which existed at that time.The coast classification work began in the former Vancouver Forest Region insouthwestern British Columbia (Klinka et al. 1979, 1980). In 1976, ecosystem clas-sification work began in the coastal por-tions of the Prince Rupert Forest Region,which then encompassed the Mid-Coast,North Coast, and Queen Charlotte Islandforest districts. Since that time, extensiveecological sampling has occurred, andreports, theses, maps, and field guidesproduced which describe the biogeocli-matic units and site units—both forestsand wetlands—of coastal British Columbia(Yole et al. 1982; Banner 1983; Banner et al. 1983, 1986, 1987, 1988, 1989, 1993;Banner and Pojar 1987; Pojar et al. 1988;McLennan and Mamias 1992; Green andKlinka 1994; Klinka et al. 1995; Nuszdorferand Boettger 1994; MacKenzie and Moran2004). During this period, forest compa-nies were also carrying out ecosystem clas-sification work within some of the coastalTree Farm Licences () (e.g., Lewis1982; Beese 1983).

In 1981, the Royal British ColumbiaMuseum sponsored an expedition to theBrooks Peninsula on northern VancouverIsland to document the natural andhuman history of the area, and to examinethe evidence for a glacial refugium on thepeninsula (Hebda and Haggarty 1997).Vegetation and soil studies on the penin-sula highlighted the similarities betweenthis hypermaritime “appendage” onnorthern Vancouver Island and the blan-ket bog–upland forest complex of theouter coastal lowlands and nearshoreislands of the mainland coast to the north(Hebda et al. 1997; Maxwell 1997).

The HyP3 Project has focused primarilyon the most hypermaritime portions ofthe Coastal Western Hemlock Zone. Theunique character of this area—its prep-onderance of blanket bogs and lower-productivity “boggy” forests—has sparked

1.3 PreviousStudies: Historical

Perspective

7

controversy about whether it should beincluded within the CWH zone, or sepa-rated out as a distinct zone. Much of thiscontroversy stems from the difficultiesfaced in assessing the relative roles of cli-mate and landscape factors (e.g., subduedtopography, lack of glacial deposits, domi-nance of igneous intrusive bedrock geolo-gy) in controlling ecosystem developmentand distribution on the outer coast. Pojarand Annas (1980) proposed that this areashould be considered a distinct zone, theCoastal Cedars–Pine–Hemlock (CCPH)Zone, and for several years it maintainedthis zonal status within the Ministry ofForests system. During the 1980s, acomprehensive correlation of coastal bio-geoclimatic and site units and reassess-ment of plot data helped to determinethat the zonal ecosystem within the“CCPH” was not sufficiently differentfrom other CWH zonal ecosystems to differentiate the area as a separate zone.Though the controversy continues, the unique blanket bog–upland forest complex that characterizes the outer coastis currently included as a very wet, hyper-maritime subzone of the CWH zone(CWHvh).

1.3.3 Ecological studies in southeastAlaska The forest and wetland ecosystemsof north coastal British Columbia andsoutheast Alaska are very similar innature. Zach (1950) recognized the appar-ent tension between forest growth andbog development in southeast Alaska, and was the first to question whether“muskeg,” rather than upland forest, rep-resented the true climax ecosystem. Wehave drawn on several other Alaskan stud-ies to help understand the relationshipsbetween vegetation and environmentalong north coastal British Columbia(Lawrence 1958; Stephens et al. 1970;Neiland 1971). Neiland’s work (1971) is themost comprehensive treatment of theserelationships within the “Forest–BogComplex” of southeast Alaska. Most of

the ecosystems described by Neilandoccur along the north and central coast,though some significant differences areevident, such as the lack or scarcity ofamabilis fir and western redcedar insoutheast Alaska. Recent descriptions ofthe “ecological subsections” of southeastAlaska (Nowacki et al. 2001) also illustratethat, despite differences in classificationconcepts and nomenclature, our CWHvhsubzone in British Columbia extendsnorth into Alaska. Both British Columbianand Alaskan researchers agree that ecosys-tem classification concepts and units mustbe correlated between the two jurisdic-tions (D. D’Amore, U.S. Department ofAgriculture, Juneau, Alaska, pers. comm.,Dec. 2004).

1.3.4 Palynological studies With the aimof reconstructing past vegetation and cli-mate history, the coastal bogs and otherwetlands of the Pacific coast have been the subject of considerable palynological(i.e., study of the pollen record in peatand sediment profiles) investigation overthe last 60 years. While many of thesestudies have concentrated on describingbroad regional trends in vegetation andclimate change since the last glacial retreat(Heusser 1960; Mathewes and Heusser1981; Hebda 1995), others have emphasizedmore localized interpretation of pollenprofiles to reconstruct successionalsequences in the vicinity of specific sam-pling sites (Hebda 1977; Banner et al. 1983; Turunen and Turunen 2003). Thelatter approach has helped shed light onthe successional relationships betweenbogs and forests on the north coast. Thispalynological evidence, in combinationwith studies of soil profiles and naturaldisturbance events such as windthrow(Ugolini and Mann 1979; Bormann et al.1995), suggests that paludification, whichresults from impeded drainage and mossencroachment of forested sites on mineralsoils, is an important soil-forming processon the outer coast, and has significant

8

implications for forest productivity(Banner et al. 1983; Klinger 1990).

1.3.5 Forest management researchBecause of the dominance of lower-productivity sites on the outer northcoast, the question of their potential contribution to the operable land base has been discussed for many years. In1975, a research project was initiated bythe Prince Rupert Forest Region with the following objective: “… using soil investi-gations and various studies of plantecosystems, produce a map which willindicate the potential productivity of a siteor whether it is possible to improve it foreconomic gain” (B.C. Ministry of Forests1975). Although a small cedar-poling trialwas established in the Lachmach Valley in1975, changing staff priorities led to theshelving of this project in 1978; however,prompted by a high demand for cedar and perceived future interest in expandingthe operable land base into these lower-productivity cedar-types, this same issueresurfaced 15 years later. In 1990, a projectfunded by South Moresby Forest Replace-ment Account () was initiated atPort Simpson to look at mounding as asite treatment to improve productivity incedar-hemlock forest types (Beaudry et al.1994). A sister project was also establishedon Haida Gwaii/the Queen CharlotteIslands that built upon the initial work ofGreen (1989) who studied site–forest pro-ductivity relationships in lowland ecosys-tems on eastern Graham Island.

In 1997, after the completion of a prob-lem analysis of the issue (Kayahara andKlinka 1997), we decided to expand thePort Simpson research into a more inte-grated investigation of the ecological pat-terns and processes within the coastalblanket bog–upland forest complex. TheHyP3 Project was initiated with ForestRenewal BC funding obtained in 1997, andthe Port Simpson study became part ofthis larger integrated research project.

On northern Vancouver Island, a related management issue dates back tothe 1960s when considerable areas of old-growth western redcedar–westernhemlock forests were harvested and regen-erated with redcedar, hemlock, and Sitkaspruce. Regeneration problems emerged,especially with Sitka spruce. After severalyears of acceptable growth, this speciesbegan to show severe nutrient deficienciesand steadily declining growth rates. Thesesymptoms were not evident in adjacentsecond-growth western hemlock–amabilisfir stands that originated from a wide-spread 1906 windstorm. Comparison of these two forest types led to severalhypotheses about the causes of poorergrowth and nutrition on the cedar–hemlock sites. The Salal–Cedar–HemlockIntegrated Research Program ()was initiated in the early 1980s to test sev-eral of these hypotheses and to establishtrials looking at the potential for variousmechanical and chemical treatments toimprove second-growth productivity(Prescott and Weetman 1994; Blevins andPrescott 2002).

Some notable differences exist betweenthe forest ecosystems on northernVancouver Island and those on the main-land coast to the north. • Yellow-cedar and mountain hemlock

occurring on the outer north coastcommonly extend to sea level, whereasfurther south both species are typicallyrestricted to montane and subalpineforests.

• Cedar–hemlock forests that dominatethe north coast tend to be lower in pro-ductivity and generally wetter thanthose on northern Vancouver Island.

• Salal (Gaultheria shallon) is less domi-nant and less vigorous on the northcoast than on northern VancouverIsland, although other ericaceousshrubs (mainly Vaccinium spp.) arecommon in the understories of northcoast forests.

9

• Glacial deposits (till, outwash), whichare typical of northern VancouverIsland, are relatively uncommon on thenorth coast, with most soils developingfrom weathered bedrock, colluvium, ororganic material.Many of the results from and

other northern Vancouver Island studies(Douglas and Courtin 2001) are undoubt-edly applicable to more northern ecosys-tems; however, ecological differencesbetween the two areas (CWHvm1 andCWHvh1 on northern Vancouver Islandvs. CWHvh2 on the outer central andnorth coast) are significant enough thatdirectly extrapolating harvesting andregeneration experience from the south to the north coast would not be appropri-ate. The HyP3 Project has thus built onexisting information from byestablishing additional studies on thenorth coast where, to date, we have had

relatively little experience with second-growth management of lower-productivi-ty forests.

Recent literature shows that forestmanagers in southeast Alaska are alsoconcerned about the limits of sustainableforest operability. Studies of forest pro-ductivity on transitional “forested wet-lands” conclude that these forests meetthe “minimum standard for commercialtimberland,” but also recognize that man-aging these areas for timber productionpresents many ecological and operationalchallenges (Duncan 2002; Julin andD’Amore 2003). Over the past 20 years,joint field trips with colleagues in south-east Alaska have highlighted that BritishColumbia shares many of the same forestmanagement issues, and that significantpotential exists for co-operation inresearch efforts.

10

The geographic scope of the HyP3 Projectencompasses the Coastal WesternHemlock zone, Very Wet Hypermaritimesubzone, Central variant (CWHvh2) with-in the North Coast and North Island –Central Coast forest districts of the CoastForest Region. The CWHvh2 includes all coastal islands and a mainland fringealong the central and north coast ofBritish Columbia, from Smith Inlet in thesouth to the Alaska border in the north(Banner et al. 1993) (Figure 1.3). Althoughthe CWHvh2 also occurs on the western-most Queen Charlotte Ranges andSkidegate Plateau on Haida Gwaii/theQueen Charlotte Islands, our HyP3 studiesdid not include these areas. The study arealies primarily within the traditional terri-tory of the Tsimshian on the north coast,but also extends into the territories of theNisga’a, Haisla, Heiltsuk, Nuxalk, andOweekeno First Nations.

The CWHvh2 occurs in the HecateLowlands and westernmost KitimatRanges physiographic regions (Holland1976), and extends from sea level toapproximately 600 m elevation. TheHecate Lowlands form part of the HecateDepression, and encompass a low-lyingstrip of subdued and rocky terrain alongthe outer coast, extending inland to anelevation of approximately 600 m. TheKitimat Ranges are eroded, predominantlygranitic, mountains that rise to an eleva-tion of 2300 m to the east of the HecateLowlands, and are part of the CoastMountains physiographic region (Holland1976).

The geology of the north and centralcoast is complex and fragmented with

numerous bedrock types, but dominatedby plutonic and metamorphic groups(Figure 2.1). Plutonic rock, mostly quartzdiorite and granodiorite, is the most common bedrock type encountered in the area. The regions of metamorphicbedrock are more scattered and are acomplex mixture of rock types, mostlyschist and gneiss (Hutchison et al. 1979).Areas dominated by granitic bedrockinclude Princess Royal Island, EcstallRiver, southern Grenville Channel, andFitz Hugh Sound. Areas of metamorphicbedrock include Khutzeymateen Inlet,Tsimpsean Peninsula, Kaien Island, andnorthern Grenville Channel. Localizedareas of limestone occur on the coast,mostly in association with metamorphicbedrock. Highly mixed geology character-izes Stephens, Porcher, Banks, Pitt, andAristazabal islands; Rivers Inlet; andSmith Sound (Hutchison et al. 1979;Roddick et al. 1979).

Although most of the north and centralcoast was glaciated during the last ice age,glacial deposits are rare. This is likely dueto a combination of high precipitationand steep topography (at least inland ofthe Hecate Lowlands) resulting in the ero-sion of deposits into the valley bottoms,and then into the sea (Hutchison 1967).The dominant surface materials arebedrock, saprolite, colluvium, and organ-ic deposits. Colluvium is more commonin the steeper Kitimat Ranges, and organicdeposits are more common on the gentlyrolling topography that dominates theHecate Lowlands where drainage is poor(Valentine et al. 1978).

2 LOCATION AND ENVIRONMENTAL SETTING

2.1 Location,Physiography,

and Geology

11

The climate of the outer north and centralcoast is oceanic, characterized by mildtemperatures, high rainfall, and lowevapotranspiration (Table 2.1). The win-ters are extremely wet and relatively mild;sub-zero temperatures may occur forshort periods when cold, arctic air coversthe area. In general, the Pacific Oceanmoderates temperatures throughout theyear, and the Coast Mountains serve toprotect the outer coast from cold winterand hot summer continental air masses(Banner and Pojar 1987). The CoastMountains also promote orographic rain-fall, making areas closer to the mountains

wetter than those on the offshore islands(Environment Canada 1998).

For the most part, precipitation occursas rain, with little snowfall and many daysof fog. With an average of over 220 daysper year of recorded rainfall, prolongeddry sunny periods are rare (EnvironmentCanada 1998). Soils in this wet environ-ment are made even wetter by low evapo-transpiration, which results in a very highmoisture surplus during the growing season. This moisture surplus likely has agreater influence on plant growth and dis-tribution than does total annual precipita-tion (Banner and Pojar 1987).

. Generalized bedrock geology, central and north coast ofBritish Columbia.

2.2 Climate

12

The vegetation of the outer north coast isa complex of productive forests, lower-productivity forests, bog forests, bogwoodlands, and blanket bogs (Figures2.2–2.6). The latter three are consideredwetlands or wetland-like ecosystems andcover more than 50% of the landscape(Banner et al. 1988, 1993). The disturbanceregimes characteristic of the outer coasthave led to a regeneration process domi-nated by gap dynamics in these forests. Asa result, most forests are old growth withan uneven age structure (Lertzman et al.1996) dominated by shade-tolerantconifers, such as western hemlock andwestern redcedar (Banner et al. 1993).

The major tree species on the outercoast are western redcedar, western hem-lock, yellow-cedar or cypress, shore pine,Sitka spruce, amabilis fir, mountain hem-lock, and red alder (Alnus rubra) (Banneret al. 1993). Both yellow-cedar and moun-tain hemlock are found from sea level to subalpine elevations in the CWHvh2(mostly in lower-productivity forests andbogs at lower elevations), whereas thesespecies are restricted to higher elevationsin south coastal British Columbia.

Average or “zonal” sites (i.e., sites thatreflect the overriding influence of regionalclimate) in the CWHvh2 are much wetterthan zonal sites in any other subzone inBritish Columbia. The forests are open

and scrubby, and are dominated by west-ern redcedar, yellow-cedar, and westernhemlock; shore pine and mountain hem-lock occur in variable amounts. Forestproductivity (normally expressed as siteindex) on zonal sites is often low com-pared to zonal sites found in other CoastalWestern Hemlock subzones (Banner et al.1993). The shrub layer is usually welldeveloped, and is dominated by salal(Gaultheria shallon), blueberry (Vacciniumspp.), and false azalea (Menziesia ferrug-inea). Common species in the herb layerinclude bunchberry (Cornus canadensis),deer fern (Blechnum spicant), false lily-of-the-valley (Maianthemum dilatatum),heart-leaved twayblade (Listera cordata),and skunk cabbage (Lysichiton ameri-canum). The moss layer is dominated bylanky moss (Rhytidiadelphus loreus) andstep moss (Hylocomium splendens),though common green sphagnum(Sphagnum rubiginosum and S. girgen-sohnii) and large leafy moss (Rhizomniumglabrescens) are often found. Productiveforests are located mainly on moderate tosteep, often colluvial, slopes with gooddrainage, and on floodplains; areas of pro-ductive forest are typically interspersedwith lower-productivity forests and openbogs (Banner et al. 1993). The forested siteseries of the CWHvh2 and their positionon the edatopic grid (Banner et al. 1993)

. Climatic data for the CWHvh2 and some adjacent subzones (Banner and Pojar 1987; Reynolds 1997)

Mean Mean Mean Mean Number ofLocation and Mean annual temperature temperature annual annual days withbiogeoclimatic Elevation temperature warmest coldest month precipitation snowfall rainfallsubzone (m) (°C) month (°C) (°C) (mm) (cm) > 0.2 mm

Prince Rupert, CWHvh2 34 6.7 13.1 –0.2 2523 152 233Bonilla Island, CWHvh2 16 8.0 13.2 2.8 2104 62 222Ethelda Bay, CWHvh2 8 7.7 13.7 1.9 3186 144 235McInnes Island, CWHvh2 25 8.5 14.3 2.9 2558 98 233Kitimat, CWHvm1 128 6.4 15.9 –4.5 2299 548 195Ocean Falls, CWHvm1 5 8.1 16.1 0.2 4387 155 218Stewart, CWHwm 5 5.2 14.5 –5.2 1851 556 164Alice Arm, CWHws1 314 4.5 14.1 –5.8 2074 841 n/aKemano Kildala Pass, 1609 –1.4 6.9 –8.5 2793 1816 n/a

MHmm1

2.3 Vegetation,Soils, and

Ecosystems

13

. Upland productive forest type, CWHvh2/06.

. Upland scrub forest type, CWHvh2/01.

. Bog forest type, CWHvh2/11.

. Bog woodland forest type, CWHvh2/12.

. Blanket bog, CWHvh2/32.

14

are depicted in Figure 2.7. Detaileddescriptions of these site series can befound in Chapter 5 (section 5.2).

The soils of the forested portion of theCWHvh2 are imperfectly drained Podzolsand Folisols with deep surface organiclayers. Wetland organic soils (Fibrisols,Mesisols, and some Humisols) are alsocommon. Brunisols and Regosols can befound on floodplains, and Gleysols arecommon on wet sites where mineral hori-zons remain saturated for extended peri-ods (Banner et al. 1993). Whatever the soiltype, their formation and composition are influenced greatly by the underlyingbedrock geology. Because of a lack of gla-cial till in this area, mineral soils are large-ly formed from decomposed bedrock(saprolite) or from colluvium. Bedrocktypes vary greatly in their resistance toweathering (Valentine et al. 1978) and thusin their rate of decomposition and nutri-ent release. For example, plutonic graniticbedrock is the most resistant to weather-ing and gives rise to relatively thin,

nutrient-poor mineral soils comparedwith metamorphic rocks (Kranabetter andBanner 2000; see section 4.5.1). Climate is also very important in soil formation,with high rainfall leading to stronglyleached, nutrient-deficient Podzolic min-eral soils. The extreme amount of mois-ture experienced in the hypermaritimeenvironment contributes to the saturated,anaerobic soil conditions that promotemoss growth and hinder decompositionof organic matter; such conditions resultin thick accumulations of organic forestfloor materials (Banner et al. 1993).Consequently, on much of the outer coastwhere the terrain is gentle, organic mate-rials have accumulated to form extensivepeatland areas (Figure 2.8). These peat-lands usually contain a scrubby or sparsetree layer in a mosaic of open bogs, bogwoodlands, and bog forests. Peat depthvaries from less than 50 cm on the mostexposed outer coastal islands to severalmetres in some areas near Prince Rupert.

01020304050607080910111213

Western redcedar – Western hemlock – SalalShore pine – Yellow-cedar – RacomitriumWestern redcedar – Yellow-cedar – SalalWestern hemlock – Sitka spruce – Lanky mossWestern redcedar – Sitka spruce – Sword fernWestern redcedar – Sitka spruce – FoamflowerWestern redcedar – Sitka spruce – Devil’s clubSitka spruce – Lily-of-the-valley (High fluvial bench) Sitka spruce – Trisetum (Middle fluvial bench) Red alder – Lily-of-the-valley (Low fluvial bench) Western redcedar – Yellow-cedar – Goldthread (Bog forest) Shore pine – Yellow-cedar – Sphagnum (Bog woodland)Western redcedar – Sitka spruce – Skunk cabbage (Swamp forest)

Site Series

07,08, 09

03

05

01

0604

02

11

10, 1312

verypoor

A

poor

B

medium

C

rich

D

veryrich

E

very xeric 0

Relative

xeric 1

subxeric 2

submesic 3

mesic 4

subhygric 5

hygric 6

subhydric 7

Actual

slightlydry

fresh

very moist

wet

moist

Soil Nutrient Regime

Soil

Moi

stur

e Re

gim

e

Sites of most interest to the HyP3 Project

. Edatopic grid depicting forested site series of the CWHvh2 subzone (Banner et al. 1993). Circled site series (04, 01,and 11) are of most interest to the HyP3 Project.

15

Disturbance histories are distinctly differ-ent within the CWHvh2 between forestson the steep slopes of the Kitimat Rangesand those on the gently rolling terrain ofthe Hecate Lowlands. In general, high for-est productivity is associated with well-drained and aerated sites on steep slopes,often with a history of natural disturbanceby landslide or windthrow events over thepast several hundred years. These distur-bance events tend to mix soil layers, slowing the buildup of surface organicmaterial, exposing mineral soil, andimproving nutrient availability (Bormannet al. 1995). More frequent natural distur-bances also occur on the floodplains oflarger rivers (e.g., the Skeena), as well ason smaller more confined systems. Fluvialdisturbance by flooding can occur annual-ly or every few years, depending on benchheight and weather conditions.

In contrast to productive forests onsteep slopes and floodplains, the lower-productivity cedar-dominated sites foundon the Hecate Lowlands have typicallygone for centuries without major distur-bances. This lack of disturbance, together

with much poorer drainage, has resultedin deep accumulations of organic matterand much lower levels of available nutri-ents (Kranabetter et al. 2003). In theseforests, most disturbances are small andlocalized, and most gaps are created by stem breakage or blowdown events(Lertzman et al. 1996; Nowacki andKramer 1998; Hennon and McClellan2003). Because of the more subdued ter-rain, landslides are less common on theouter coast than in the Kitimat Rangesfurther inland. In addition, large-scale dis-turbance events, such as major blowdownor fire, are infrequent throughout the area(Neiland 1971; Nowacki and Kramer 1998).Return intervals for major disturbancesare probably greater than 1000 years formost lower-productivity old-growthstands; however, our current estimates ofdisturbance return intervals are specula-tive, based on limited stand age data.Detailed age structure analysis over exten-sive areas of old-growth forest on thenorth coast is required to better quantifydifferences in disturbance regimes amongthe many forest types.

. Open bog development on 2 m of accumulated peat near Prince Rupert.

2.4 NaturalDisturbance

Regimes

16

The CWHvh2 is adjacent to several other biogeoclimatic units, including the Coastal Western Hemlock, Very WetMaritime, Submontane and Montane variants (CWHvm1 and CWHvm2), theCWH Wet Maritime (CWHwm) subzone,and the Mountain Hemlock, Wet Hyper-maritime, Windward variant (MHwh1).

The CWHvm1 occupies low-elevation(submontane) areas inland of theCWHvh2. These areas have a wet, humid,mild oceanic climate, but are somewhatcolder in the winter and warmer in thesummer than the CWHvh2. Amabilis fir ismore common than in the CWHvh2, andmountain hemlock and yellow-cedar areuncommon (Banner et al. 1993).

The CWHvm2 occupies higher-elevation (montane) areas above theCWHvm1 (above 350 m elevation). TheCWHvm2 has a shorter growing seasonand deeper snowpack than the CWHvh2and CWHvm1. Western redcedar andshore pine are uncommon in this sub-zone. Subalpine fir (Abies lasiocarpa) is

occasionally found in the eastern-mostCWHvm2, mostly in areas of cold airdrainage, while yellow-cedar and moun-tain hemlock increase in abundance fromthe CWHvm1 to vm2 (Banner et al. 1993).

The CWHwm is the most northerlyCWH subzone. It is characterized by steeprocky terrain, very heavy snowfall, andlower plant species diversity. Westernhemlock and Sitka spruce are the domi-nant tree species, with amabilis fir rare or absent, and yellow-cedar and westernredcedar infrequent (Banner et al. 1993).

The subalpine MHwh1 is found abovethe CWHvh2 on the coastal islands andadjacent low-lying mainland. The MHwh1is characterized by heavy snowfalls, ashort growing season, the dominance ofyellow-cedar and mountain hemlock, thescarcity of amabilis fir, and the absence ofsubalpine fir. The distinction between for-est and parkland is vague because of themany non-forested wetlands in this sub-zone (Banner et al. 1993).

2.5 AdjacentBiogeoclimatic

Units

Although some aspects of the HyP3

research and inventory initiatives areextensive in nature and have been carriedout throughout the North Coast ForestDistrict (e.g., Predictive EcosystemMapping), most of the intensive researchactivities have been conducted at fourstudy sites (Figure 2.9). Studies of ecosys-tem function have been carried out alongstudy transects at Diana Lake and SmithIsland. These old-growth sites have beenused to study hydrology and biogeochem-istry, ecosystem productivity and decom-position rates, peatland development andsuccession, soil ecology, and old-growthforest productivity. Operational trials havebeen established at the Port Simpson andOona River study areas. These operationaltrials have been used to study harvestingmethods, silvicultural treatment options,regeneration issues (natural and artificial),log quality and utilization, and effects of

harvesting on soil properties and bio-diversity.

2.6.1 Diana Lake The Diana Lake studysite is located within and adjacent toDiana Lake Provincial Park, 15 km south-east of Prince Rupert. Elevation rangesfrom 75 to 705 m. The study area containsa typical CWHvh2 cross-section of ecosys-tems including zonal lower-productivityforests, bog forests, bog woodlands, blan-ket bogs, swamps, and productive forestson steeper slopes. The most commonbedrock in the area is gneissic diorite,although schist is also present in somelocations. Initial studies and installation of monitoring equipment began in 1997.Ecosystem mapping and permanent plotlayout were completed, and a meteorolog-ical station, which records precipitationand wind speed and direction, wasinstalled in an open bog along one of the

2.6 HyP3 StudySites

17

study transects. Timber cruising andstream surveys were completed in thesummer of 2000. Hydrology, geochem-istry, and moss productivity studies werecarried out on a continuous basis from1997 until the summer of 2001. Somedestructive tree sampling for growth andyield purposes was also conducted at thissite.

2.6.2 Smith Island The Smith Islandstudy site is located on Smith Island inInverness Passage at the mouth of theSkeena River, 20 km south of Prince

Rupert near the community of PortEdward. The elevational range of theSmith Island site is 0–380 m. The site isdominated by lower-productivity zonalforests on gentle slopes, productive forestson steeper slopes, and bog woodlands,bog forests, and open blanket bogs. Thebedrock is largely gneissic diorite withsome schist. Studies were also initiated atthis site in 1997 and, in keeping with themethodology established at Diana Lake,ecosystem mapping and permanent plotlayout were completed and a meteorologi-cal station was installed in an open bog.

Dundas Island

Porcher Island

PittIsland

SmithIsland

Skeena River

Diana Lake

OperationalTrial

OperationalTrial

Port Simpson

Oona River

StudyArea

StudyArea

PrinceRupert

. Location of HyP3 intensive study sites and operational trial sites on thenorth coast of British Columbia.

18

Timber cruising and stream surveys were completed in the summer of 1999.Hydrology, geochemistry, and moss pro-ductivity studies were carried out on acontinuous basis from 1997 until the sum-mer of 2001. This site was initially consid-ered for harvest as an operational trial;however, visual quality issues, volumeconcerns, and the high costs associatedwith site accessibility made the harvestingimpractical.

2.6.3 Port Simpson The Port Simpsonstudy site is located 30 km north of PrinceRupert near the village of Port Simpsonon the Tsimpsean Peninsula. The opera-tional research trial was initiated in 1990and incorporated into the HyP3 Project in 1997. The area is underlain by schistbedrock and was dominated by lower-productivity zonal forest before it washarvested in the late summer of 1990.After harvest, the block was divided intoeight plots, four to be mounded and fouruntreated controls. The objective of thetrial was to study the effects of creatingmounds by mixing the mineral soil withthe surface organic horizons. The moundswere created in 1990 using an excavator,and then planted in 1991 with equalamounts of western hemlock, westernredcedar, and shore pine. At intervalsfrom 1991 to 1997, measurements of rootand shoot biomass, and height and caliperwere taken, and foliar analyses were con-ducted on the seedlings (Shaw and Banner2001a, 2001b; see Chapter 6, section 6.2).

2.6.4 Oona River The Oona River opera-tional research trial is located near thecommunity of Oona River on PorcherIsland, 40 km south of Prince Rupert at0–50 m elevation. The study area compris-es two adjacent cutblocks of 10.2 ha and7.4 ha. These blocks are primarily com-posed of three ecosystem types: the lower-productivity zonal forest, which accountsfor approximately 84% of the harvestedarea, and smaller patches of bog woodland

and productive upland forest. The domi-nant bedrock at Oona River is schist. Theinitial block identification, layout, andecosystem mapping for this trial began in1998. The blocks were harvested in June2000. Late in 2001, plots were establishedto test the effects of three site preparationtreatments: light scarification and raking,light scarification and raking with phos-phorus fertilization, and spot raking fol-lowed by mixing surface organic materialwith mineral soil to form low mounds. All site preparation treatments were com-pleted using a tracked excavator. Aftertreatments were applied, the blocks wereplanted with western redcedar and yellow-cedar in the spring of 2002 (LePage et al.2002; see Chapter 6, section 6.3). Moni-toring of seedling growth and nutritionbegan in 2003 and will continue at regularintervals.

The intensive HyP3 study areas estab-lished to date contain good representationof CWHvh2 forest and bog ecosystems in areas of gneissic diorite and schistbedrock. The study areas were chosen, inpart, because the cedar–hemlock stands on these bedrock types were considered(based on earlier ecosystem sampling) tohave the greatest potential for forest man-agement and, in part, for logistical rea-sons. In addition to the more intensivestudies carried out at these locations, vari-ous studies involving ecosystem descrip-tion, classification, and mapping, soilecology, regeneration, and site productivi-ty were completed at sites throughout thenorth coast that encompass the full spec-trum of bedrock types (see Chapters 4 and5). To compare findings with the trials onmetamorphic rock and to expand theapplications and management interpreta-tions of the HyP3 Project, plans are cur-rently under way to establish additionaloperational trials in areas of granodioritebedrock. One such study area at RainbowLake, near Prince Rupert, has been laidout in preparation for harvesting.

19

Water plays a pivotal role in shapingecosystem function on the outer coast.For this reason, detailed hydrologicalstudies are an important part of the HyP3

Project. In hypermaritime ecosystemssuch as these, it is critical to comprehendthe relationships between water and land-scape processes, as well as hydrologicalresponses to forest management actions.Changes in both forest composition andsoil properties influence hydrologicalresponses. Forest harvesting and silvicul-tural treatments manipulate the forest

canopy, thus affecting rainfall interceptionand transpiration, and the amount ofwater reaching the forest floor. Roadbuilding, site disturbance, and site prepa-ration modify soil drainage patterns andthe rate of water runoff. The water-drivenbiogeochemical processes governingnutrient availability are also influenced byaltered site hydrology. An understandingof how these hydrological changes willaffect long-term forest dynamics and siteproductivity is important in the practiceof sustainable forest management.

3 HYDROLOGY AND BIOGEOCHEMISTRY

3.1 Introduction

Watershed hydrology is the study of watermovement and storage within a unit ofland that drains all water to a commonoutlet (Black 1996). Forest managementactivities can alter water movement andstorage within a watershed by changingrunoff timing and magnitude (Bosch andHewlett 1982). Hydrological effects relatedto forest harvesting and road buildinginclude decreased canopy interceptionand evaporation, decreased transpiration,changes to snow accumulation and melt,and altered soil hydrology. The watershedhydrology of an area is frequently describedusing a “water balance” approach inwhich watershed inputs, storage, and outputs are measured. Water inputs areprimarily rain and snow; storage is ground-water within the soil; and outputs areevaporation, transpiration, and runoff.The quantification of each of these ele-ments within undisturbed watersheds isimportant to gain an understanding ofhow forest ecosystem disturbances willaffect soil moisture, runoff, sedimenta-tion, and paludification (bog formation).Some initial water balance research in theCWHvh2 was carried out by Beaudry andSager (1995); the watershed hydrologystudies of the HyP3 Project were designedto expand on this work.

In mountainous areas, precipitationcan increase with elevation. As moist air islifted over a barrier, it cools and the watervapour condenses and falls. This is knownas orographic precipitation. The relation-ship between precipitation and topogra-phy is complex, but is mainly affected bythe prevailing wind direction, speed, andhumidity. Orographic precipitation canhave a significant influence on the waterbalance of watersheds in mountainousterrain and, therefore, it must be consid-ered in water balance calculations.

Canopy interception plays an impor-tant role in determining the amount ofrainfall reaching the forest floor. During arainfall event, water either penetrates thecanopy falling directly to the understoreyor forest floor, or is intercepted by thecanopy. From there it can drip to theground surface, flow down tree stems, or be held and evaporate. The portionthat falls directly to the ground or dripsfrom the canopy is termed “throughfall.”Rainfall that is intercepted and flowsdown the tree trunk is known as “stem-flow,” and the remainder is called “inter-ception.”

The amount of rainfall intercepted by a forest canopy depends on storm size,intensity, duration, weather conditions,

3.2 WatershedHydrology

20

forest structure, tree species and architec-ture, tree age, tree density, and epiphyticgrowth of mosses and lichens (Crockfordand Richardson 1990; Beaudry and Sagar1995; Calder 1998; Spittlehouse 1998).Depending on these conditions, the forestcanopy may intercept 15–35% of annualrainfall.

Removal of the forest canopy in a wetenvironment will introduce more water toalready wet soils. Potential effects of thisincreased water include larger peak waterflows, increased erosion, and decreasedslope and channel stability (Spittlehouse1998). A higher water table could alsoresult, changing the ecology of the site andleading to regeneration problems, lowertree productivity, and paludification.

3.2.1 Study approach Our methods arepresented briefly here; if more detail is required, refer to the source papers(Maloney and Bennett 2002; Maloney etal. 2002; Emili 2003). Meteorological sta-tions were set up in open bogs at both theSmith Island and Diana Lake study sites to

measure precipitation and wind directionand speed. For orographic effects on rain-fall, measurements were made in openingsat several elevations in both watersheds,and at the sea-level site at the NorthPacific Cannery in Port Edward (referencestation). Throughfall was measured usingten 5-m troughs at each site (Figure 3.1).At Diana Lake, two rectangular “fogharps” strung with vertically orientedmonofilament were used to measure thetiming and relative magnitude of fog dripfrom January to August 1998.

Stemflow was measured on 17 trees atSmith Island and 15 trees at Diana Lakeusing 10-mm collars wrapped 1.5 timesaround each tree (Figure 3.2). Stream dis-charge was measured using a combinationof continuous water level recordingdevices, stream gauging, and V-notchweirs (Figure 3.3). Automatic recordingdevices were installed on most installa-tions. Hemispherical photography wasused to determine the canopy closureabove the throughfall troughs (Frazer et al. 2000). Forest stand characteristics

. Trough system used to collect rain “throughfall” data at the Diana Lake study site.

21

were measured using standard prism(variable radius) cruise plots for stemsover 7.5 cm diameter at breast height(), with supplemental fixed-area plotsfor stems under 7.5 cm . For the mostpart, hydrological installations were main-tained for 7–8 months per year (April toOctober or November) and thus data donot reflect annual conditions.

Water balances (or budgets) weredetermined for watersheds at the SmithIsland and Diana Lake sites using theequation:

. V-notch weir for measuring discharge on a bog stream at Diana Lake study site.

. Stemflow collectionsystem on a redcedartree at the Smith Islandstudy site.

Precipitation = stream discharge + evapotranspiration +/– groundwater storage

The precipitation, evaporation (assumedto equal interception), and dischargecomponents were measured directly.Precipitation at the North Pacific Cannerywas measured year-round, while precipi-tation at the Smith Island and Diana Lakesites was recorded from April to Octoberor November. Stream discharge at theSmith Island and Diana Lake sites was

measured year-round. The change in stor-age was assumed to be negligible overtime periods as short as a few years, espe-cially if the water year selected starts andends at a time when the soil moisture isnear its maximum (Dingman 2002).Transpiration was the only componentthat was not measured, and thereforecould be calculated using the above equa-tion; however, this calculation also con-tains all measurement errors and is onlyconsidered as a rough estimate of actualtranspiration (Maloney and Bennett2002). Interception was measured inforested ecosystems and thus evaporationvalues for the entire study watershedswere calculated by multiplying the inter-ception values by the percentage of thewatershed that was forested (vs. open bogand other non-forested areas) (Maloneyand Bennett 2002).

Canopy interception was determinedusing the equation:

Interception = precipitation – (throughfall + stemflow)

22

Hydrological response (runoff ratio) is the ratio of discharge (mm) to rainfallinput (mm). Lag time closely approxi-mates the time in hours from when one-half of the rainfall in the event fell towhen one-half of the discharge from theevent occurs.

3.2.2 Results: hydrological response andtiming An analysis of 18 discrete rainfallevents showed that the hydrologicalresponse and lag time for both watershedsvaried with event size and the weatherconditions that preceded the event. Thiswas particularly noticeable in the hydro-logical response to small rainfall eventsfollowing a dry period, which ranged from0.18 to 0.21 (Figure 3.4). If a small eventfollowed a wet period, the hydrologicalresponse almost doubled (0.32–0.38). Thehydrological responses for large rainfallevents varied widely regardless of themoisture conditions that preceded therainfall event. The hydrological responsefor large rainfall events preceded by wetand dry conditions ranged from 0.26 to0.81. Although small events after a wetperiod had a higher response than thoseafter dry periods, the response was neveras great as the maximum recorded fromsome large events. In addition, lag timewas shortest if the rainfall event occurred

within 48 hours of the previous rainfallevent.

3.2.3 Results: orographic rainfall Rainfalltotals at the Smith Island and Diana Lakesites were consistently higher than at theNorth Pacific Cannery reference site atPort Edward (Table 3.1). The high-eleva-tion sites at Diana Lake also recordedhigher totals than the Smith Island sites.Within the Diana Lake watershed, thehillslope site recorded 6.8% more rainfallthan the hilltop site, even though the siteswere at the same elevation. The DianaLake high-elevation sites were 2.3 kmapart on opposite sides of a valley, eachwith topographically different surround-ings. The hillslope site was at a 337 m ele-vation on the leeward side (north aspect)of a 750-m mountain, while the hilltopsite was on top of a 337-m hill.

Although 60% of rainfall events at bothsites occurred within the 1–19.9 mm cate-gory (Figure 3.5), the greatest amount ofrainfall (26%) occurred within the 20–39.9 mm category (Figure 3.6). Approx-imately 55% of annual rainfall resultedfrom events greater than 40 mm. Rainfallat both watersheds was closely linked towind direction. Approximately 88% oftotal rainfall at the Diana Lake and SmithIsland sites occurred with wind from the

Lag tim

e (ho

urs)

Dry 7–11

Wet 5–7

Dry 5–10

Wet 4–6

0.10 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Hydrological response

Even

t si

ze < 50

mm

> 50

mm

. Hydrological response and lag time for small (< 50 mm) and large (> 50 mm) rainfallevents in the Smith and Diana watersheds. “Wet” and “dry” refer to whether or notrainfall occurred within the previous 48 hours.

23

. Total monthly rainfall by site and elevation, correlated (r) to theNorth Pacific Cannery reference site at Port Edward (July–October1999 and May–October 2000)

Total measured

rainfall DifferenceSite (mm) (%) r

Cannery (0 m) 2476 n/a n/aSmith (52 m) 2596 +4.9% 0.99Smith (332 m) 2747 +11.0% 0.99Diana Met (72 m) 2834 +14.5% 0.99Diana south (337 m) 2979 +20.4% 0.99Diana north (337 m) 3149 +27.2% 0.98

100

90

80

70

60

50

40

30

20

10

01– 20– 40– 60– 80– 100– 120– 140– 160– 180–

19.9 39.9 59.9 79.9 99.0 119.9 139.9 159.9 179.9 199.9

Cannery

Diana 72 m

Diana Hilltop

Diana Hillslope

Event size (mm)

No.

of e

vent

s

. Frequency distribution of rainfall events greater than 1 mm at the Diana Lake study site.

24

southeast (121°) to the south-southwest(210°) (Table 3.2). All large rainfall eventsalso occurred with wind from this quad-rant.

3.2.4 Results: canopy interception, fogdrip, and stemflow Over the ice-freemonitoring periods from May toNovember, 1999–2001, an average of 1862 mm/yr of rain fell at Smith Island,and 1943 mm/yr at Diana Lake (Table 3.3).The average annual interception rate was25% at Smith Island and 21% at DianaLake (Table 3.3). These results are similarto those of Spittlehouse (1998), whoobserved interception rates of 30% formature coastal western hemlock forests on Vancouver Island, and of Beaudry andSagar (1995), who observed interceptionrates of 21% for a coastal redcedar–west-ern hemlock forest at Port Simpson, 25 km north of Prince Rupert. Monthlyinterception at Smith Island ranged from12 to 46%, and at Diana Lake from 15 to39% (Table 3.4). Maximum interceptionwas observed during the dry summermonths, and minimum interception dur-ing the wettest months.

For individual rainfall events, intercep-tion varied from 10 to 100% (Figure 3.7).The wide range of interception is due tothe size, length, and intensity of the rain-fall event, and timing relative to otherevents. Interception decreased with bothevent intensity and event duration, espe-cially for medium- and long-durationevents (Table 3.5). Interception was lowestfor events of long duration, regardless ofintensity or canopy state. Interception was greatest, and stemflow and through-fall lowest, during low-intensity, short-duration events, regardless of the canopysaturation level. For these events, inter-ception was roughly 62–70% at SmithIsland and 69% at Diana Lake. For low-intensity, long-duration events, intercep-tion was roughly 30% at Smith Island and22% at Diana Lake. The wet or dry condi-tion of the canopy before the event didnot have a major effect on interception. Inthe dry canopy, throughfall began shortlyafter the start of a storm event, while adelay in stemflow was evident until thecanopy was saturated.

Fog drip was detected on 59% of thedays during the sampling period

30

25

20

15

10

5

0

Tota

l rai

nfal

l (%

)

Cannery

Diana 72 m

Diana Hilltop

Diana Hillslope

1– 20– 40– 60– 80– 100– 120– 140– 160– 180–19.9 39.9 59.9 79.9 99.9 119.9 139.9 159.9 179.9 199.9

Event size (mm)

. Percent of total rainfall by event size category at the Diana Lake study site.

25

. Percentage of rainfall by wind direction

% of total rainfall

Diana Lakea Smith Islandb

Direction Bearing (°) Cannery 72 m Hillslope Hilltop Cannery 52 m 331 m

NE Quadrant 0.1–90 0.3 0.3 0.3 0.3 0 0 0NNE 0.1–30 0 0 0 0 0 0 0NE 30.1–60 0 0 0 0 0 0 0ENE 60.1–90 0.3 0.3 0.3 0.3 0 0 0SE Quadrant 90.1–180 59.8 61.1 59.5 60.5 79.8 79.5 79.0ESE 90.1–120 1.1 1.4 1.4 1.4 6.9 7.0 6.9SE 120.1–150 25.4 25.0 26.4 25.2 23.5 22.9 23.0SSE 150.1–180 33.2 34.7 31.8 33.9 49.5 49.6 49.1SW Quadrant 180.1–270 39.8 38.3 39.7 38.9 20.0 20.2 20.4SSW 180.1–210 29.6 28.9 30.2 29.1 14.4 14.8 14.8SW 210.1–240 8.1 7.6 7.4 7.7 3.6 3.3 3.3WSW 240.1–270 2.1 1.8 2.1 2.1 2.0 2.1 2.3NW Quadrant 270.1–360 0.1 0.3 0.4 0.3 0.2 0.4 0.5WNW 270.1–300 0.1 0.3 0.4 0.3 0.2 0.4 0.5NW 300.1–330 0 0 0 0 0 0 0NNW 330.1–360 0 0 0 0 0 0 0

Total rainfall (mm) 2475 2833 3149 2979 2475 2595 2745

a Cannery results calculated using Diana Lake anemometer.b Cannery results calculated using Smith Island anemometer.

. Annual rainfall, throughfall, stemflow, and interception at the Smith Island and Diana Lakesites (May–November, 1999–2001)

Smith Island Diana Lake

Total Canopy Total Canopyrainfall throughfall Stemflow Interception rainfall throughfall Stemflow Interception(mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm)

1999 2133 1443 22.9 667 2156 1673 17.6 4652000a 1793 1345 21.0 427 1800 1429 15.5 3562001a 1659 1308 22.1 329 1873 1446 15.6 412Average 1862 1366 22.0 474 1943 1516 16.2 411% 73.4 1.2 25.5 78.0 0.8 21.2

a To account for canopy variability, the location of throughfall troughs changed to five new locations for2000 and 2001.

. Maximum and minimum monthly interception as a percentage of rainfall at the SmithIsland and Diana Lake sites (May–November, 1999–2001)


Total Totalrainfall Interception Interception rainfall Interception Interception(mm) (mm) (%) (mm) (mm) (%)

Maximum 515.5 62.3 12.1 607.5 91.7 15.1Minimum 60.5 27.9 46.1 73.5 28.9 39.3

26

120

100

80

60

40

20

0

Inte

rcep

tion

%

Diana Lake

0 50 100 150 200

Rainfall (mm)

. Interception as a percentage of rainfall, by rainfall event, at the Diana Lake and SmithIsland sites. Calculations assumed a constant stemflow of 1.2% at Smith Island and 0.8%at Diana Lake.

120

100

80

60

40

20

0

Inte

rcep

tion

(%)

0 50 100 150 200

Rainfall (mm)

Smith Island

27

(January–August 1998) and 99% of thisoccurred during rainfall events. However,with the type of collectors used in thisstudy, it was difficult to differentiate thecontributions of fog, drizzle, and rain.Compared with studies of fog drip inother coastal forests (Azevedo andMorgan 1974; Harr 1982), the amount offog drip, as indicated by throughfall in the absence of rainfall, was lower thanexpected in these north coast forests.Nevertheless, cloudwater or fog dripinputs may be more substantial at higherelevations or at more exposed locationson the north coast; fog could thus be asignificant source of nutrient inputs tosome sites (Bormann et al. 1989).

Stand stemflow as a percentage of totalrainfall averaged 1.2% at Smith Island and0.8% at Diana Lake (Table 3.3). At SmithIsland, monthly stemflow ranged from 1.1to 1.3% of total rainfall, while at DianaLake, stemflow measured 0.8% of totalrainfall. The differences in monthlystemflow are likely due to a number offactors, including canopy state (dry orwet), and rainfall intensity and angle(Crockford and Richardson 2000).

In general, large trees produced agreater amount of stemflow than theirproportion of the stand at both sites, withdead trees producing less (Table 3.6). The

larger trees have a greater interceptionarea and also extend above the maincanopy. The absence of foliage on deadtrees means that there is less surface areato intercept rainfall, and thus lessstemflow. The results from the smallertree classes were mixed, making interpre-tation difficult.

Stemflow represents a small compo-nent of forest hydrology, but it plays animportant role in directing water to treeroots, and while the added water may notbe important in hypermaritime areas,stemflow is often enriched with nutrientsfrom tree canopies and trunks. Soalthough stemflow represents a small per-centage of total water input, it has beenshown to have a larger effect on the qual-ity of water entering the soil (Johnson1990).

3.2.5 Results: water balance Water bal-ances were performed for the Smith Islandand Diana Lake watersheds betweenSeptember 1, 1998, and August 31, 2001.Each water balance was performed for awater year (September to August). Resultsare summarized in Table 3.7. A separatewater balance was performed for an addi-tional small watershed in the Diana Lakestudy area; however, because of the nega-tive residual values for this watershed, the

. Rainfall interception sorted by canopy condition, event intensity, and event length


Canopy Intensity Event length Interception Interception condition (mm/hr) (hrs) n average (%) n average (%)

Wet (< 24 hrs Low < 5 117 62 78 69without rain) (≤ 1 mm/hr) 5–24 109 41 104 30

> 24 29 30 19 22High < 5 6 37 4 28(> 1 mm/hr) 5–24 38 24 26 17

> 24 31 19 32 18Dry (> 24 hrs Low < 5 45 70 20 69without rain) (≤ 1 mm/hr) 5–24 21 41 24 28

> 24 4 30 6 21High < 5 0 – 2 43(> 1 mm/hr) 5–24 14 28 11 24

> 24 9 23 11 19

28

. Production of stemflow by tree size class


Sample Sampletrees in % of % of trees in % of % of

Tree Class class trees stemflow class trees stemflow

< 7.5 cm 3 50 52 4 42 35 7.5–17.5 cm 2 13 1 3 26 33 > 17.5 cm 8 13 30 5 9 20Dead trees 4 24 17 3 23 12

. Water balance for the Smith Island and Diana Lake watersheds, 1998–2001

Groundwater ChannelPrecipitation Evaporation storage change discharge

Location (mm) (mm) % (mm) % depth (mm) % Residuala %

Smith Island1998–1999 3613 797 22.1 0 0 2433 67.3 383 10.61999–2000 3930 805 20.5 0 0 2448 62.3 677 17.22000–2001 3650 664 18.2 0 0 2634 72.2 352 9.6Average 3731 722 19.4 0 0 2505 67.1 504 13.5

Diana Lake1998–1999 4110 586 14.3 0 0 3110 75.7 414 10.01999–2000 4523 659 14.6 0 0 3604 79.7 260 5.72000–2001 4158 602 14.5 0 0 3210 77.2 346 8.3Average 4264 616 14.4 0 0 3308 77.6 340 8.0

a Residual value includes transpiration and measurement error.

results were deemed less reliable and are not presented here. For a completedescription of the HyP3 water balancestudies, see Maloney and Bennett (2002).

The Diana Lake study site had a greaterorographic effect and, therefore, averageprecipitation values were higher there(4264 mm) than at Smith Island (3731mm). Stream discharge accounted for 78%of annual precipitation at Diana Lake and67% at Smith Island. Evaporation (calcu-lated using forest interception data andforest cover information for each water-shed) accounted for 14% (Diana) to 19%(Smith) of precipitation. This left averageresidual values of 8% at Diana Lake and14% at Smith Island, a portion of whichwould be transpiration with the remain-der accounted for by measurement error.Maloney and Bennett (2002) outlined var-ious sources of error in hydrology studies,

including error estimates of ± 5% forstream discharge values and ± 10–15% forinterception values. Winter interceptionwas an additional uncertainty in thisstudy. October interception values wereused to estimate winter interception; how-ever, winter interception will depend onhighly variable weather conditions, espe-cially the percentage of precipitationfalling as snow (Schmidt and Troendle1992; Pomeroy and Schmidt 1993; Woo etal. 2000). The estimated transpiration forthe HyP3 study watersheds is thus expect-ed to contain a considerable element oferror.

Beaudry and Sagar (1995) completed awater balance for a coastal cedar–hemlockecosystem north of Prince Rupert using acombination of climate and interceptionmeasurements and climate modelling.Their study lacked streamflow data, but

29

derived evapotranspiration values throughmodelling; in contrast, the HyP3 studieshad extensive streamflow data, but lackeddetailed estimates of transpiration. For thewater balance, Beaudry and Sagar calcul-ated streamflow to represent 75% of totalprecipitation, with evaporation and tran-spiration representing 21% and 4% of

precipitation, respectively. These stream-flow and evaporation estimates, as well astotal precipitation (3673 mm), are compa-rable with the HyP3 study sites, especiallythe Smith Island site; therefore, a transpi-ration estimate of ± 4% may be reason-able for these hypermaritime watersheds.

How water behaves in the soil has a largeinfluence on the way a site reacts to har-vesting-induced changes in hydrology.Soil composition (i.e., whether the soilsare dominated by mineral or organicmaterials) is an important factor in the soil response on the north coast.Ecosystems with soils dominated byorganic materials include some zonalscrub forests, as well as bog forests, bogwoodlands, and open peatlands. In addi-tion to soil composition, hydrologicallinkages between forests and wetlands can also affect hydrological responses.

Typically, peat-dominated sites (e.g.,bogs) have two main soil layers. The 10–50 cm upper layer contains plant materials,both live and poorly decomposed, includ-ing roots and the remains of vascular andnon-vascular vegetation. The lower layeris primarily perpetually saturated,

well-decomposed organic material(National Wetlands Working Group1997). The surface layer is the most hydro-logically active, with flow rates that may beseveral orders of magnitude greater thanin the lower layer (Ingram 1983). Conse-quently, when the water table is near or atthe surface of the bog, the water is free tomove through the more active surfacelayer (Waddington and Roulet 1997).

Soil pipes are a type of macroporethat run nearly parallel to the soil surface(Figure 3.8) and are commonly found in many soil types (Uchida et al. 2001).Water flow through pipes is calledpipeflow. Pipeflow can be a critical hydro-logical process that allows the rapid trans-fer of water to stream channels. Soil pipesare thus important in determining effec-tive hydraulic conductivity. Pipes can be disturbed by harvesting activities,

3.3 SoilHydrology and

Biogeochemistry

. Conceptual model of discontinuous soil pipes forming linkages withlocalized dynamic contributing area.

30

potentially changing the drainage patternsof the harvested area.

Soil biogeochemistry, and changes toits dynamics, can also have significanteffects on forest management and otherresource values. For example, plant pro-ductivity is closely tied to nutrient avail-ability, which in turn can be affected bywater table height and soil aeration. Bothwater table height and aeration can bealtered by forest harvesting practices.

Carbon cycling is another biogeochem-ical process that can be affected by har-vesting. Carbon cycling in the highlyorganic soils of the north coast involvesthe movement of large amounts of dis-solved organic carbon () within the soil profile (Vance and David 1991).Dissolved organic carbon increases wateracidity and darkens the water, which givesrise to the naturally tea-coloured water ofthe area. The dark water, in turn, lowerslight penetration, while the increasedacidity influences nutrient availability andincreases the ability of the water to trans-port metals (Davies-Colley and Vant 1987;Driscoll et al. 1989; Driscoll et al. 1995).High levels in streamwater also haveimportant implications (both positive andnegative) to aquatic biological processes.

3.3.1 Study approach Soil hydrology wasstudied at both the Diana Lake and SmithIsland research sites. Numerous methodswere used to determine the hydrologicaldynamics of the sites. Our methods arepresented here briefly; if more detail isrequired, refer to the source documents(Gibson et al. 2000; Lortie 2002; Fitzgeraldet al. 2003; Emili 2003).

Meteorological stations were placed inopen bogs at both study sites to measureprecipitation. V-notch weirs were set upin several locations in the watersheds totrack discharge. Wells and piezometerswere installed in specific vegetation typesthroughout the study areas to determinewater table depth and hydraulic head.Time domain reflectrometry ()

probes were used to measure soil moisturecontent. Automatic recording data-loggerswere included at many of these instal-lations.

Hydraulic conductivity was determinedusing bail tests, and hydraulic gradientswere calculated using a combination oflevelling across the study area and relativewater table measurements. Water sampleswere either collected by hand or withautomatic collecting devices; chemicalanalyses were done in the laboratory.

Natural and artificial tracers were com-monly used to determine groundwaterflow rates and pathways, and water contri-butions from different sources (e.g., vege-tation types and soil layers). The tracersused included , ratios of the isotopesof oxygen (18O/16O) and hydrogen(2H/1H), salt water, and dyes. In somecases, hydrograph separation techniqueswere then used to determine the quantityof water contributed to streams by differ-ent sources before, during, and after rain-fall events. Hydrological responses torainfall events were ascertained using acombination of rainfall data, water tableheights, stream discharge volumes andcurves, the chemical composition ofwater, and hydrograph separations.

3.3.2 Results: water tables Depth to the water table was much greater in theupland forest than in the other vegetationtypes (Table 3.8). The shallowest watertable depth occurred in the swamp forestwhere the water table was often above theground surface. In most cases, differencesin water table depths are closely related toforest productivity. In general, the siteswith low water tables are more productivefor trees than those where the water tableis near the surface, saturating the rootingzone. The swamp forest, however, is anexception—the surface topography allowstrees to establish on elevated and better-aerated microsites, and to absorb (some ofthe) nutrients in the relatively rich miner-al seepage of the saturated depressions

31

(Banner et al. 1993). The physical amountof water table fluctuation, as indicated bythe standard deviation, was similar at allsites. At sites with high water tables, how-ever, the water table is often very close tothe surface where the saturated conditionsaffect tree growth.

3.3.3 Results: soil hydrological dynamicsThe hydrological dynamics of the outernorth coast depend on several interactingfactors. Ground surface slope, as shownby a slope index (that combines slopeangle and slope length), influencesdrainage rate and, therefore, water tableheight and soil moisture content (Emili2003). Lower slopes and depressions arewetter and tend to accumulate organicmatter in the form of peaty soils. Thisrelationship is quantified by the slopeindex that, in turn, is related to vegetationtype and organic soil depth (Emili 2003).These findings correspond with those ofAsada (2002), who found that vegetationtypes were most influenced by water tabledepth and slope.

Peaty soils, in a positive feedback loop,profoundly influence soil drainage charac-teristics. These organic soils have a lowhydraulic conductivity, which decreaseswater infiltration rates and groundwaterflow, and restricts soil water discharge(Emili 2003). The soils also have a high

water retention capacity, which enablesthem to retain pore water for long per-iods, and thus remain saturated. Wet soilconditions facilitate the accumulation oforganic matter, restrict tree growth, andfavour the establishment of wetlandspecies, such as sphagnum mosses andsedges.

The low hydraulic conductivity of theorganic soil matrix encourages alternativesubsurface pathways (e.g., pipes andmacropores) to develop, which are criticalin removing water from these sites. Oftenshort (5–10 m) and terminating in seepsand rills, these pathways permit morerapid water movement than the regularsoil matrix flow (Gibson et al. 2000). Thelow hydraulic conductivity of organic soilsalso results in surface flow during stormevents.

Hydraulic conductivity is also animportant factor in the variation of waterresidence times in organic and mineralsoil-based terrain types. In organic soils,low hydraulic conductivity results in soilwater retention and, therefore, littleunused storage capacity is available toabsorb water from the next rainfall event.This forces new water to leave organicsoils quickly. As a result, streams inorganic soil terrain types are less stable(i.e, “flashier”) than those in mineral soilterrain types (Gibson et al. 2000). In

. Average depth to water table, pH, and dissolved organic carbon (DOC) of groundwater frommineral and organic soil horizons by site series (adapted from Emili, 2003)

pH DOC (mg/L)

Water table depth Organic Mineral Organic Mineral Site series (cm) (SD)a horizon horizon horizon horizon

Upland forest (04) 93.0 (7.1) n/a 6.03 n/a 8.2Scrub forest (01) 22.2 (7.6) 5.04 5.52 17.6 11.1Bog forest (11) 14.3 (6.5) n/a 5.19 12.6b 7.5b

Bog woodland (12) 15.3 (5.0) 4.89 5.44Open peatland (32) 7.9 (6.9) 4.85 5.62 16.6 10.2Swamp forest (13) 3.2 (5.4) n/a n/a n/a n/a

a Standard deviation.b DOC data combined for the bog forest and woodland vegetation types.

32

addition, runoff patterns are influenced bythe weather conditions preceding a stormevent.

Hydrological dynamics differ with rain-fall intensity and between the soil surfaceand subsurface layers. These differencesare attributed, in part, to the presence ofpeat, which maintains a shallow watertable (Gibson et al. 2000). In the scrubforest, the shallow groundwater systemresponds rapidly to rainfall events, as indi-cated by a rapid rise in water table and concentrations in the shallowgroundwater and streams during rainfallevents, but not in the deep groundwater.A shallow water table keeps most of the inputs of water in the near-surfacegroundwater zone, and much exchangeoccurs with the surface as groundwaterseeps. Incoming water moves through the upper soil layers, exits the soil fromnumerous groundwater seeps, and flowsover the ground surface before reachingthe stream. Conversely, the deep ground-water system shows little reaction to rain-fall events (Gibson et al. 2000; Lortie2002). The deep groundwater zone only

receives a small proportion of the newwater inputs, especially in the bogs,because of the low hydraulic conductivityof deeper organic horizons, and the rela-tively few macropores in the deeper soilhorizons (Gibson et al. 2000; Lortie 2002).

At low rainfall intensities, a “first-in-first-out” hydrological dynamic generallyexists, where old water is pushed out ofthe system using internal soil flow path-ways. At high rainfall intensities, the flowcapacities of these pathways are exceededand alternative pathways involving rapidflow (i.e., rill and seep flow) are invoked.This results in a “last-in-first-out” hydro-logical dynamic, where streamflow isdominated by new water (Gibson et al.2000) that usually travels through shallowgroundwater pathways before reaching thestream (Figure 3.9). After rainfall events,deep groundwater resumes its role as themajor contributor to streamflow. Therainfall threshold at which the flow-patternchange occurs is not known, but is likelylower after harvesting because of thedecreased rainfall interception by thecanopy.

. Model of groundwater flowpaths in zonal forests and open bogs in the Smith Island watershed. Dashed lineis the water level beneath the ground surface and in the stream. Solid lines represent the groundwaterflowpaths: SH = shallow hillslope flowpaths; DH = deep hillslope flowpaths; SB = shallow bog flowpaths; DB = deep bog flowpaths; S = groundwater seep.

33

3.3.4 Results: pipeflow studies In northcoast lowland forests, four main factorsappear to facilitate the development ofsoil pipes:1. presence of a soil discontinuity with

depth (i.e., a highly conductive surfaceorganic layer [1–55 m/day] overlies alow-conductivity [0.0004–0.002 m/day]peat);

2. steep hydraulic gradients;3. organic soils with low cohesion; and4. high volume of living roots and buried

coarse organic material.In this setting, pipes may form by

a subsurface flow through the surfaceorganic layer, which cuts into the underly-ing, more decomposed organic soil. Withlittle solid soil structure to hold it in place,this organic soil is often eroded, allowingpipe formation. Pipes were found through-out soil profiles at the study sites, but weremost abundant at structural voids androots (i.e., at the junction between high-and lower-conductivity soil horizons), at the soil–root interface (Figure 3.10a),along conduits of decayed roots, andalong the soil–bedrock interface (Figure3.10b).

Excavation revealed that channelledsections of pipes were continuous overshort distances (5–10 m). Water tracingwith salt water and dye, however, showedthat hydraulically effective and connectedflow paths occurred over much longer dis-tances, likely through linkages at nodes.These nodes can be tree root masses, areaswith more highly hydraulically conductivesoil, deadfalls, or zones where overlandflow occurs.

During a storm, the size of an area con-tributing to direct runoff expands andcontracts according to a theory known asthe “variable source area concept” (Dunneand Black 1970). This area is calculatedusing the following formula (Jones 1997):

Total storm discharge

Area =in pipe or stream (m3)

Total storm rainfall (m)

This formula uses the amount of waterdischarged during an event and theamount of rainfall that fell during anevent to determine the area that con-tributed to discharge.

The area that contributes water to apipe during storms may be enlarged by a

. Examples of soil pipes: (a) excavated soil pipes formed around live roots located in a cedar–hemlock forest; (b) soilpipeflow directed into a bucket weir for measurement of discharge.

ba

34

rising water table, overland flow fromperched saturated zones, or groundwaterwhich discharges at the surface and flowsinto pipe channels. This drainage systemis similar to the discontinuous macro-pores on forested hillslopes in Japandescribed by Sidle et al. (2001), althoughthe north coast of British Columbia has a much wetter hydrological regime.

Two basins were chosen for monitor-ing, each with different physical character-istics (Table 3.9). These basins werechosen for their small size, which facili-tated the integration of climate–soil–vegetation dynamics, their proximity topre-existing monitoring areas, and theircontrasting drainage systems. The largerof the two basins, the “S01 basin,” is dom-inated by a small first-order stream, whichoriginates near the toe of a scrub forestslope at the margin of a bog containing anabundance of buried deadfall. The streammeanders for about 30 m before discharg-ing into “Smith small stream.” Runofffrom the second basin, the “K-pipe basin,”is dominated by a 10–20 cm diameter soilpipe that is 30–50 cm below the surface atthe organic–mineral and mineral–bedrockinterfaces. The K-pipe basin was tracedvisually over 7 m from its discharge pointthrough a wave-cut terrace on the beach

at Inverness Passage (Figure 3.10b). Liveand dead tree root masses and areas ofponded water occurred at irregular inter-vals along this pipe. Beyond 7 m, surfaceevidence of the pipe vanished into a thick (> 1.5 m) deposit of peat. Along a 100 m section of the wave-cut terrace,eight smaller soil pipes were noted. Withthe exception of one other perennial pipe,all of these flowed ephemerally.

Though similar CWHvh2/01 forestsdominate both basins, notable differencesare apparent in soil characteristics andtopography (Table 3.9). Soil depth at theS01 basin averaged 0.6 m on hillslopes,greater than 1.5 m in mid-slope boggybenches, and greater than 3 m in the bogforest. Soil depth at the K-pipe basin wasseldom greater than 1.2 m, with hydraulicconductivity averaging three orders ofmagnitude greater than the S01 basin.Here, the zone of highest conductivityroughly coincided with the suspecteddepth of the pipe channel.

Surface water storage exerts a greaterinfluence over the K-pipe basin than theS01 basin; swampy areas of standing watercover approximately 20% of the K-pipebasin. During storms, these areas expandto form a network of pools linked by areasof return flow. Presumably, this is the

. Characteristics of the S01 and K-pipe basins

S01 basin K-pipe basin

Basin area (m2) 7331 2763

Drainage first-order stream Perennial soil pipe

Slope 8–38° 5–10°

Soil thickness (m) 0.1 to > 3 0.5–1.5

Hydraulic conductivity (m/d) 0.00038–0.13 2–51average = .024 average = 25

Dominant vegetation Approx. 50% moderately sloping Gently sloping scrub forest: westernscrub forest: western redcedar, redcedar, yellow-cedar and hemlock,yellow-cedar and hemlock; and with interspersed swamp forest andapprox. 50% gently sloping bog abundant surface pools.forest, scattered areas with standing water.

Dominant site series 70% 01 scrub forest 70% 01 scrub forest 30% 11 bog forest 30% 13 swamp forest

35

surface expression of pipe channel flowunder pressure, as the pipe channel variesits course both vertically and horizontallywithin the soil profile (Woo and Dicenzo1988). In contrast, the S01 basin has muchsmaller isolated pools of standing waterthat are restricted to riparian zones at thebase of the CWHvh2/01 hillslope and atscattered sites throughout the bog forest.

The typical stormflow and ground-water response (Figure 3.11) to a well-defined, single-peak storm event was rapidfrom both the K-pipe and S01 basins, withsimilar peak rainfall to peak dischargetimes for each. The response time (meas-ured as the difference between the start ofrainfall and initial increase in discharge)for the K-pipe basin, however, was abouttwice as rapid (average of 2 hours). Evenwhen the antecedent groundwater level inboth basins was similar, the thresholdgroundwater level required to initiatestormflow differed. In the S01 basin, anincrease in stream discharge coincidedwith a water table rise to within 5–10 cmof the surface. In the K-pipe basin, pipedischarge started to appreciably increasewhen the water table rose above the baseof the pipe channel, which was about 30 cm below the ground surface. Baseflowseparation revealed consistently highercontributions of baseflow to the K-pipebasin (16–44%) compared with the S01basin (10–34%).

The S01 basin receded much faster than the K-pipe after storms, exhibitingprogressively steeper recessions withdecreasing discharge (Figure 3.12a and3.12b). The abrupt recession observed inthe S01 basin is explained by smaller con-tributions from baseflow, rapid discon-nection from the bog forest and hillslopesource areas, the lack of dynamic storagein the stream channel, and seepage lossesto the gravel streambed and surroundingsoil. Conversely, the extended recessionsobserved in the K-pipe basin imply amore intimate contact with the watertable, and greater post-peak contributionfrom swampy surface depressions draining

through surface macropores and higher-conductivity soils.

The dynamic contributing areas ()for the S01 and K-pipe basins were com-pared with measures of basin wetness todetermine the controls on runoff (Figure3.13). The S01 basin’s is generally wellpredicted by the following measures ofbasin wetness:• antecedent water level (r 2 = 0.70–0.95);• 1-day antecedent soil moisture

(r 2 = 0.48–0.75); and• 5- and 10-day antecedent precipitation

(r 2 = 0.63–0.75).The K-pipe basin s had somewhat

different relationships with measures ofbasin wetness. The s grew withincreasing antecedent precipitation toabout 20 mm. Between 20 and 50 mm 10-day antecedent precipitation, contributingareas began to shrink. Contributing areahad an inverse relationship with the fol-lowing precipitation indices: magnitude,intensity, rainfall depth before peak flow,and storm duration. The apparent shrink-ing of s as the catchment becomeswetter is explained by the activation ofephemeral soil pipes under very wet con-ditions. With increasing catchment wet-ness, these pipes serve to divert stormflowaway from the K-pipe basin, which resultsin a smaller apparent contributing area.This was corroborated by the pipeflowtracer experiments, which establishedconnections between the K-pipe basin anda number of neighbouring ephemeralpipes.

Compared with the S01 basin, the K-pipe basin experienced a more rapidresponse to precipitation and more grad-ual recessions because of its intimate contact with the water table, higher-conductivity soils, and affiliation with anetwork of smaller ephemeral pipes andnodes. Another factor involved in therapid response of the K-pipe basin, andexpansion of the contributing area duringa storm, is its large area of swamp forestwith significant surface depression storage.Swamp forests can have a large proportion

36

1.5

1.0

0.5

0

148 149 150 151 152

Day of year (May 27–30, 2000)

Dis

char

ge (

L/se

c)

0.85

0.80

0.75

0.70

Soil

moi

stur

e (c

m3 /

cm3 )

1

0

–1

–2

–3

–4

–5

–6

–7

Wat

er t

able

(cm

)

0

1

2

3

4

5

Prec

ipita

tion

(mm

/h)

K-pipeSO1 stream

TDR response (~3 m from SO1 stream)

Recording wells SO1 basin(distance from weir)

Bog–forest well (28 m)

Riparian 01 well (39 m)

Midslope 01 well (45 m)

(a)

(b)

(c)

(d)

. Comparison of typical storm hydrograph response between the K-pipeand S01 basins: (a) precipitation during event; (b) water table depth atthree locations; (c) soil moisture response in S01 basin; (d) dischargeprofile from the K-pipe and S01 basins.

37

of a basin’s water routed through them,causing discharge to increase rapidly whenstorage capacity is exceeded (Fitzgerald etal. 2003). In the S01 basin, streamflow isfed primarily by shallow subsurface flowthrough the near surface peat and byoverland flow as the water table intersects

the ground surface. Consequently, the S01basin becomes rapidly disconnected fromsource areas as the water table declines.Because the S01 basin has much steeperslopes and contains only a minimal areaof swamp forest, overland flow and pref-erential flow are common, but largelyrestricted to discrete areas of the basin.

3.3.5 Results: hydrological landscape link-ages The mosaic of vegetation types typi-cal of the north coast suggests thathydrological linkages between site seriesare common; therefore, forest manage-ment actions may have hydrologicaleffects that extend beyond the boundaryof the harvested forest type. Some foresttypes may have a larger controllinginfluence on watershed hydrologicaldynamics than others. This section sum-marizes the results of an investigation ofhydrological linkages among several siteseries within the Diana Lake study area.

Bog isolation By definition, bogs arepeatlands that receive water input exclu-sively from direct precipitation (NationalWetlands Working Group 1997).

1.61.41.21.00.8

0.6

0.4

0.2D

isch

arge

(lo

g10

L/s

ec)

0 0.5 1.0 1.5 2.0

Time (days)

(a) May 30June 15June 19June 25August 11August 18August 20August 22August 27

1

0.1Dis

char

ge (

log

10 L

/sec

)

0 0.5 1.0 1.5 2.0

Time (days)

May 30June 15June 19June 25August 11August 18August 20August 22August 27

(b)

. Selected storm recession graphs for the (a) K-pipe and (b) S01 basins during the 2000 fieldseason.

3

2

1

0

DC

A (

000

m3 )

0 10 20 30 40 40 60 70 80

10-day antecedent rain (mm)

K-pipe basinS01 basin

. Relationship between the S01 basinand K-pipe basin dynamiccontributing areas (DCA) and 10-day antecedent rain.

38

Consequently, bogs are usually consideredto have no groundwater and surface waterinputs from the surrounding landscape.Some evidence, however, suggests that thisisolation is less absolute than previouslythought (Siegel et al. 1995). Establishingthis hydrological autonomy is essential tounderstand the implications of disturb-ances in the forests adjacent to wetlandecosystems. For example, if bogs arehydrologically isolated, and no harvesting-related activities occur directly on the bogsurface, then activities on slopes above orbelow the bog may not greatly affect thehydrology of the bog itself. To furtherexamine this issue, we attempted to char-acterize the nature and strength of thehydrological linkage between a bog thathas developed within a complex land-scape, and the adjacent forests, specificallythe CWHvh2/04 and /01 site series at theDiana Lake study site.

Water budgets for two rainfall events(July 22 and 28, 1999) were used to deter-mine whether the bog experienced anywater inputs or exports. During the firstrainfall event, 17 mm of rain fell in

20 hours, and during the second event, 56mm fell in 47 hours (Figure 3.14a). Usingthe water budget equation (see section3.2.1), we calculated that 121 m3 of rain fellon the bog during the first event. Of thisamount, 106 m3 was taken up in ground-water storage and 13 m3 was dischargedover the stream weir, which accounted for119 m3 of the 121 m3 input (Figures 3.14band 3.14c). Evapotranspiration over theduration of the storm event was likelynegligible and, therefore, ignored. For thesecond event, we calculated that 400 m3 ofrain fell. Of this amount, 350 m3 was dis-charged, 9 m3 was stored as groundwater,and 41 m3 was stored in surface pools thatcovered about 10% of the catchment area.

The full accounting of the input, stor-age, and discharge from two storms, oneof which followed a dry period, the othera wetter period, demonstrates the hydro-logical independence of this bog systemfrom adjacent ecosystems. During the firstevent, most of the rainfall was accountedfor by the change in water storage withinthe bog—almost no water was lost by sur-face drainage through the stream. For the

discharge (l/sec) over bog stream weir

Rain

fall

(mm

/h)

135

July 19–31, 1999

19 20 21 22 23 24 25 26 27 28 29 30 31

Dis

char

ge (

L/se

c)

0

3

6

Wat

er t

able

rel

ativ

eto

gro

und

surf

ace

(cm

)

–20

–15

–10

–5 missing data

zero discharge

average of 5 wells

well on north side of bog(ground surface at 173.1 m)

well at bog stream edge(ground surface at 171.3 m)

(a)

(b)

(c)

. Hydrological parameters measured in a bog at the DianaLake study site: (a) precipitation; (b) bog water tableelevation relative to ground surface; and (c) dischargerecorded at the bog weir.

39

second event, inputs were primarilyaccounted for by discharge and storagechange (i.e., water table rise).

Despite the macro-scale topographicconnection between the bog and the adja-cent forested slope, no apparent hydrolog-ical linkage exists between them as seen bythe lack of water inputs from these areas.This lack of water transfer between theforest and bog is due to subtle differencesin elevation and flow paths at the marginsof these two systems. Seepage losses at thefoot of the forested CWHvh2/04 slope(Fitzgerald et al. 2003) are intercepted by aseepage channel that skirts the perimeterof the bog on its northern side. Thus, ifforestry activities occurred on the slopesabove this bog, the bog’s hydrologicalbudget and its ecological integrity wouldbe largely unaffected. The bog wouldincur little environmental damage, as longas machinery did not traverse the bog,including the bog margins. This bog,however, does not represent all peatlandson the outer coast because this landscapeproduces wetlands in many different top-ographical and hydrological settings. Eachspecific situation must be properly inter-preted before concluding that adjacentecosystems are hydrologically isolated.

Swamp forest and hillslope interactionsSwamp forests (Western redcedar – Sitkaspruce – Skunk cabbage; CWHvh2/13 siteseries) are localized in water-receivingareas such as lower slopes and depres-sions. Although relatively common in theCWHvh2, these forests generally do notcover extensive areas. Swamp forests wererecognized as being hydrologically con-nected to other forest types, but thestrength of this linkage was not known. A study carried out at Diana Lake wasdesigned to investigate the relationshipbetween swamp forests and the adjacentforests that provide water to them, in thiscase, an upland productive forest(CWHvh2/04).

This study showed that the swamp for-est was fed by both ground and surface

water from the upland productive forest.During rainfall events, up to 95% of thewater in the stream was routed throughthe swamp forest, though it only occupied25% of the catchment area (Fitzgerald etal. 2003). This water was held in theswamp forest before its release to thestream. Between rainfall events, the pro-portion of water in the stream comingfrom the swamp forest steadily declined asthe water table dropped.

The upland productive forest also dis-charged water into the stream via seeps.The discharge in these seeps was not sen-sitive to variation in the water table heightin the upland productive forest. The dis-charge from the swamp forest, however,was sensitive to water table changes. Thisindicates that harvesting activities on theupland productive forest will have less ofan effect on stream hydrology than har-vesting of the swamp forest (Fitzgerald etal. 2003). If these swamp forests are har-vested, the water table could rise (Dubé etal. 1995), decreasing available water stor-age capacity, increasing peak water flows,and potentially increasing the risk offlooding (Fitzgerald et al. 2003). Our pre-liminary results suggest that harvesting ofswamp forests should be avoided becauseof potentially negative on-site and off-sitehydrological impacts. In the specific situa-tion at this study site, hydrological link-ages exist between the hillslope productiveforest and the swamp forest. Therefore,removal of the canopy on the hillslopeforest and the resulting interception andevaporative losses would have someinfluence on the swamp forest below andindirectly affect stream flows.

3.3.6 Results: soil water chemistry Meangroundwater pH for all forest types com-bined was lower in the organic horizonsthan in the mineral horizons (Table 3.8).The differences in soil water pH betweenhorizons is likely due to the acidic natureof coniferous forest litter, the acidifyingabilities of sphagnum and other mosses inthe organic layer, and the higher pH of

40

the mineral soil itself. In the mineral hori-zon, soil water pH was highest in theupland forest and lowest in the bog forest,though the differences were not statistical-ly significant.

Vegetation type and soil type wereimportant factors in the ionic makeup of groundwater; slope, water table depth,and groundwater flow were not significantfactors for any of the ions measured.Productive forests (CWHvh2/04) hadsignificantly higher concentrations ofbicarbonate (HCO3), sulphate (SO4), cal-cium (Ca), magnesium (Mg), and sodium(Na) than the lower-productivity scrubforest, bog forest, bog woodland, andopen bog vegetation types (CWHvh2/01,

/11, /12, and /32, respectively), while potas-sium (K) was higher in the forested com-munities (CWHvh2/01, /04, and /11) thanthe peatland communities (CWHvh2/12and /32) (Table 3.10) (Emili 2003).Groundwater from mineral soils tended tohave higher concentrations of nutrientsthan that from organic soils (Table 3.11),though the differences were not statistical-ly significant. This indicates that ground-water contact with mineral soils accountsfor the higher concentration of nutrientsin the forested vegetation types whereorganic horizons are shallower. Many ionsalso tended to have higher concentrationsin the summer than in other seasons(Table 3.12). At Diana Lake, nitrate (NO3),

. Mean ionic composition of groundwater (mg/L) in the organic and mineral subsoil horizons at Diana Lake, 1997–1998(adapted from Emili, 2003)

Soil type HCO3– Cl– NO3

– NO2– PO4

– SO4– Ca+ Mg+ Na+ K+ Fe+ Mn+ Al+ Zn+

Organic horizon 13.4 2.2 0.04a 0.02 0.02 1.9a 2.0 0.3 3.5 1.1 0.7 0.02 0.2 0.2Mineral subsoil 16.0 2.1 0.07 0.02 0.02 3.3 2.6 0.4 3.8 0.8 0.6 0.03 0.3 0.3

a One sample above detection limit (n = 153).

. Meana seasonal ionic composition of groundwater (mg/L) at Diana Lake, 1997–1998 (adapted from Emili, 2003)

Season HCO3– Cl– NO3

– NO2– PO4


Summer 20.7b 2.5b 0.12 0.01 0.02 2.3 2.9 0.6 3.6 0.9 1.6b 0.03 0.5b 0.9aFall – 1.5ab < 0.02b 0.01 0.02 3.4 3.3 0.4 1.3 0.7 0.5a 0.03 0.2ab 0.1bWinter 12.1a 3.2a 0.4 0.01 0.01 < 1.04 1.3 0.2 2.9 0.9 0.4a 0.03 0.1a 0.2abSpring 6.2b 1.4ab 0.5 0.01 0.01 3.7 1.3 0.3 2.7 1.3 0.2ab 0.02 0.2ab 0.1b

a Means within a column followed by a different letter are significantly different (p < 0.05; n = 153).b “<” indicates concentration below specified detection limit.

. Meana ionic composition of groundwater (mg/L) by site series at Diana Lake, 1997–1998 (adapted from Emili, 2003)

Site series HCO3– Cl– NO3

– NO2– PO4


Scrub forest (01) 10.5b 2.1 0.05 0.01 0.02 2.9b 1.5b 0.3b 2.6b 1.0b 0.6 0.03 0.4 0.2Bog forest (11) 9.0b 2.5 0.04 0.01 0.01 < 1.04b 1.5b 0.9b 2.3b 1.2b 0.8 0.05 0.3 0.2Bog woodland (12) 13.7b 1.6 < 0.02 0.01 0.01 < 1.04 2.7b 0.3b 1.9b 0.5a 0.9 0.01 0.1 0.3Open peatland (32) 27.8b 1.5 < 0.02 0.01 0.02 1.9c 3.8b 0.5b 2.3b 0.6a 1.1 0.02 0.1 0.5Upland forest (04) 35.0a 3.2 0.12 0.03 0.03 3.6a 10.2a 1.2a 3.2a 1.1b 0.0 0.03 0.1 0.0

a Means within a column followed by a different letter are significantly different (p < 0.05), n = 153.b “<” indicates concentration below specified detection limitc One sample above detection limit.

41

sulphate, and phosphate (PO4) concentra-tions were very low in the vegetation typeswhere the water table was high and reduc-ing conditions were present (Emili 2003).

Dissolved organic carbon concentra-tions differed with vegetation type (Table3.8), season, and soil type. Dissolvedorganic carbon was higher in the swampforest and open peatland than in the bogforest, bog woodland, and upland forest,each having progressively lower values(Emili 2003). This pattern was likely duein part to the relative thickness of theorganic horizon in the various vegetationtypes. Dissolved organic carbon was high-est in summer, which is likely linked toincreases in microbial activity when tem-peratures are warmer and rainfall is less

(i.e., less dilution). The was alsohighest in shallow groundwater, withmuch lower values in the deep groundwa-ter (Figure 3.15) (Gibson et al. 2000; Lortie2002; Emili 2003). This pattern resultsfrom the production of significantamounts of in the organic-richsurficial deposits, and less in the underly-ing mineral soils (Schiff et al. 1990). Inaddition, water that moves to deeper mineral layers loses some of its bydecomposition and absorption as it filtersdown through the soil. The positive rela-tionship between and discharge indi-cates that, during rainfall events, isflushed from the groundwater system tothe stream.

. Dissolved organic carbon () concentrations, rainfall, and stream discharge, SmithIsland watershed: (a) stream, shallow hillslope, and deep hillslope DOC response to rainfall events; (b) rainfall and stream discharge response during the rainfall event.

3.4.1 Watershed hydrology and canopyinterception Rainfall event size and awatershed’s preceding moisture condition,especially its soil water storage capacity,control hydrological response and lagtime. Rainfall events must first fill theavailable soil water storage capacity beforeproducing a hydrological response. Thestorage capacity is greater after a dry peri-od than after a wet period. A small eventpreceded by a wet period produces a

larger hydrological response and a shorterlag time because of the smaller amount ofavailable soil water storage capacity. Largerainfall events can produce larger hydro-logical responses because a greater pro-portion of the event’s water is surplus toavailable storage capacity and is discharged.

Lag times for large rainfall events close-ly match those for small events with cor-responding preceding conditions, as soilwater storage capacity is not controlled by

28

24

20

16

12

8

4

0

DO

C (

mg/

L)

Shallow hillslope

Stream

Deep hillslope

(a)

May 6–June 3, 2000

6 13 20 27 3

Stre

am d

isch

arge

(m

3 /s)

0.50.40.30.20.10.0

Prec

ipita

tion

(mm

/h)

0

2

4

6

May 6–June 3, 2000

6 13 20 27 3

(b)

3.4 Discussionand Summary

42

the size of the event but by transpiration,evaporation, and discharge. The longer lagtimes after dry periods are a result of theincreased storage capacity, and produce adelayed hydrological response.

Hypermaritime watersheds such asthose found in the CWHvh2 have a rela-tively small amount of water storagecapacity. The shallow, dominantly organicsoils typical of these watersheds have highwater retention capacity, and are fre-quently saturated in this wet climate. Thesmall amount of available water storagecapacity in these soils means that signifi-cant runoff is generated from relativelysmall storms. A dense network of soilmacropores and pipes rapidly route theexcess water downslope to stream channels.

Compared with other locations, rainfallevents in the CWHvh2 produce a largerhydrological response. Both the averagehydrological response of 0.41 and thelargest response of 0.81 are high comparedwith the weighted average of 0.20 record-ed for streams in the eastern UnitedStates, where the highest response wasbetween 0.40 and 0.50 (Hewlett 1982). Incontrast, hydrological response values of0.55 (Cheng 1988) and greater than 0.90(Hetherington 1987) were recorded forindividual rainfall events in BritishColumbia, and a value of 0.63 was record-ed following a wet period in Barrow,Alaska (Dingman 2002). In the UnitedStates studies, the 0.40 and 0.50 responsevalues were found in locations with shal-low soils and steep slopes (Dingman 2002),whereas the values recorded here were ongentle terrain with mainly organic soils.The high response on shallow slopes indi-cates that the system has little storagecapacity and rapid water transfer mech-anisms.

Most rainfall and runoff informationfor the forested watersheds along thenorth coast of British Columbia is basedon data collected at the Prince RupertAirport, which is located near sea level.Rainfall data collected for this study,

however, indicates that 27% more rainfalloccurs at higher elevations (337 m).

About 55% of annual rainfall at theDiana Lake 72-m site resulted from eventslarger than 40 mm, and 19% from events100 mm or larger, which indicates eventsproducing large hydrological responsesoccur regularly. This has important impli-cations both for harvesting and road anddrainage structure construction. The cur-rent precipitation shutdown guidelinesassume a daily drainage rate of 55 mm/day,and require a positive water balance of 100 mm before shutdown. Precipitation-based operational shutdown guidelines for the north coast are currently underreview (agra Earth and Environmental1996; Price 2002); any new guidelinesshould recognize the influence of oro-graphic rainfall in the mountainouswatersheds of the region by ensuring thatrainfall is measured locally.

Topography, wind direction, and thespatial variability of rainfall events all con-tribute to the rainfall patterns found inthe Smith Island and Diana Lake water-sheds. At Smith Island, the lower barrierssurrounding the monitoring sites are like-ly responsible for the smaller orographiceffect. In addition, the southern part ofthe island has higher elevations than thenorthern part where the monitoring sitesare located. Consequently, moist southernair masses possibly lose some of theirmoisture before reaching the monitoringsites on the north side of the island. Therelationship between rainfall and elevationis not always linear, however, and can beinfluenced by local topography over shortdistances. For example, although both areat the same elevation, more rainfall isrecorded at the Diana Lake mid-slope sitecompared with the hilltop site. This rain-fall pattern may be produced as airflowaccelerates over a barrier with a steep,narrow upwind face, which results inmore rainfall on the leeward side of amountain than on its hilltop (Daley et al.1994).

43

We did not conduct a detailed exami-nation of the contributions of cloudwaterand fog drip as hydrological and nutrientinputs (see Emili [2004] for details ofrainfall, throughfall, and fog drip inputsand chemistry). Our sampling approachdid not permit the separation of simulta-neous occurrences of fog drip from driz-zle; however, other studies have shownthat these sources of “occult precipita-tion” represent significant inputs tocoastal forests (e.g., Bormann et al. 1989;Harr 1982) and, therefore, this topic war-rants more detailed study on the northcoast.

The decrease in canopy interceptionafter harvesting increases the amount ofwater received on the ground. At the twostudy sites, the canopy intercepted20–25% of the average annual rainfall (i.e., for the May to November ice- andsnow-free study period). If the areas areclearcut, the amount of water that mustbe removed by existing hydrologicalprocesses can be expected to increase. Asimilar study found that interception afterharvesting decreased by two-thirds whenmeasured under the shrub layer (Roy etal. 2000); our measurements, however,were made above the shrub layer. Thepossible hydrological consequences of thisdecreased interception include:• a decrease in time to peak flows after

a storm;• an increase in peak flow volumes;• an increase in water table height; and• an increase in erosion, as natural

drainage pipes reach capacity soonerand more overland flow occurs.Although increased erosion of organic

soils (especially if the soil surface is dis-turbed) is possible due to their high waterretention and low cohesion qualities, therelatively gentle slopes on which theselow-productivity forests occur will experi-ence lower surface water runoff velocities,and thus lower off-site sediment trans-port, than steeper hillslopes. Higher peakflows in streams are also possible, whichmay increase the risk of erosion and

flooding (Lortie 2002). In small water-sheds, however, the risk of greatly increasedpeak flows is low (Beschta et al. 2000).

The introduction of additional water toa drainage system can be managed usingthe current watershed assessment proce-dures for road building and bridge engi-neering. By knowing the harvested areaand the watershed’s discharge characteris-tics, the increase in peak flows can beidentified and managed.

In eastern Canada, the increase inwater on forested sites after harvesting is influenced more by interception thanby transpiration (Dubé et al. 1995).Preliminary estimates of transpirationfrom the water balance studies of Maloneyand Bennett (2002) and Beaudry andSagar (1995) suggest that this is also thecase in west coast hypermaritime ecosys-tems. Modified harvesting regimes willhelp to minimize the decrease in rainfallinterception. Following regeneration ofthe harvested area, canopy interceptionbegins to increase again as trees grow.

3.4.2 Hydrological dynamics and linkagesHydrological dynamics differ among for-est types. Our study shows that swampforests (CWHvh2/13) receive much oftheir water input from other forest types,and are important in mediating dischargeflows, whereas upland productive forests(CWHvh2/04) have deeper water tablesand mainly export water. Swamp forests,therefore, are more sensitive to harvest-ing-induced hydrological changes thanupland productive forests; they should notbe harvested because of their importancein receiving water and regulatingstreamflow within a watershed, and theirpotential for increased water tables.Upland productive forests are much lesssensitive in these respects and could beharvested with fewer on-site hydrologicalimpacts. Off-site impacts to adjacentswamp forests, or other hydrologicallysensitive ecosystems, are still a potentialconcern wherever direct linkages occur.Upland scrub forests (CWHvh2/01) will

44

likely have an intermediate response, withwater tables rising slightly depending onspecific site and soil characteristics. Thesescrub forests and their potential timbervalues are currently of interest; therefore,future operational trials should monitorand quantify any hydrological impacts.Some limited data on water table fluctua-tions associated with harvesting scrubforests are available from the Port Simpsonstudy site (Beaudry et al. 1994). The effectsare quite variable and apparently relatedto local soil and topographic conditions,as well as the location of skid roads thatact as local drainage pathways. Althoughthere was no significant difference be-tween average water table heights beforeand after harvesting, in the wells locatedadjacent to skid trails, water tables tendedto drop; in the wells located away fromthe skid trails, water tables tended to rise. At the Oona River operational trial,although changes in water tables were notmeasured, the relatively small areas of flatand low-lying portions of the blocks wereobserved to have some surface pondingafter harvest that was not apparent pre-harvest.

A rise in water table could be animportant ecological problem if scrubforests are harvested. Smaller rainfallevents would saturate these forest soilsbecause of the reduced interception andtranspiration following canopy removal(Maloney et al. 2002; Dubé et al. 1995). A rise in water tables, or “watering up,”occurs in other forested wetland areas fol-lowing harvesting, especially on transi-tional sites between wetlands and uplandswhere the water table is deeper than in thetrue wetlands (Dubé et al. 1995). Rises inthe water table will vary by forest type andslope position. Higher water tables resultin less storage capacity in the soils, a shal-lower aerobic rooting zone, a greaternumber of groundwater seeps, and alterednutrient dynamics. Higher water tablesalso hamper regeneration and promotepaludification (Asada 2002).

Regeneration success can be improved

by site preparation that includes soil mix-ing and mounding (Shaw and Banner2001a, 2001b); however, care must be takento avoid creating the conditions (e.g., poolsbeside mounds) that facilitate sphagnummoss growth and paludification (Asada etal. 2002). If forest regeneration is success-ful, canopy interception will increaseagain as trees grow. In fast-growing NewZealand pine plantations, runoff parame-ters (e.g., peak flows, quick flows, and lowflows) returned to pre-harvest levels 10years after replanting (Fahey and Jackson1997). The rate of canopy development inharvested scrub forests of coastal BritishColumbia is expected to be considerablyslower, however.

In a study of peak streamflows in rela-tion to forest harvesting on easternVancouver Island, Hudson (2002) usedthe concept of equivalent clearcut area() that accounts for hydrological re-covery due to forest regeneration. He foundthat the mean response to a decrease in of 10% (as sites regenerated) was adecrease in peak flow of 40–50%.

Forestry activities adjacent to wetlandsinvolve possible hydrological effects, rang-ing from the complete cut-off of waterinputs to the wetland to a considerableincrease in water inputs. The magnitudeof these effects will depend on the degreeto which the wetlands are hydrologicallyisolated. Decreases in water inputs couldresult from constructing logging roads onslopes that feed wetlands; increases inwater inputs (e.g., from the streams thatfeed wetlands) could result from remov-ing the adjacent forest canopy. At bothextremes, these activities may initiatechanges in hydrology that could affectwetland functioning and species composi-tion. To avoid any negative effects, it willbe necessary to assess whether the exten-sive bog and other wetland ecosystemstypical of the CWHvh2 landscape arehydrologically connected to areas plannedfor harvest. Reconnaissance-level topo-graphical and stream channel surveys areeffective procedures in such assessments.

45

3.4.3 Soil pipes Our study results showthat soil pipes play an important role indraining forests in the hypermaritimenorth coast. The two contrasting studysub-catchments had different water trans-port mechanisms, and harvesting willaffect each differently. With its gentlerslopes, the K-pipe basin will likely experi-ence a greater water table rise, and soilpipes will be most important in watertransfer from the site.

Soil pipes transport stormflow rapidlyand efficiently; however, if harvestingdamages these pipes, they could become“short-circuited,” decreasing their capaci-ty to route stormflow through the land-scape. Harvesting also reduces canopyinterception, which may result in greatersoil water inputs and thus more overlandflow, higher peak discharge rates, andshorter lag times (Ziemer 1992; Keppelerand Brown 1998).

Soil pipes can contribute to soil stabil-ity in two ways:1. by increasing the rate of soil drainage;

and2. by limiting the development of

perched groundwater conditions(Uchida et al. 2001).If soil pipes become mechanically dam-

aged and blocked, the increase in porewater pressure could trigger landslides(Ziemer 1992; Uchida et al. 2001), althoughthis is highly dependent on local hillslopeconditions (Keppeler and Brown 1998).Even under natural conditions, landslidesmay be triggered during large rainfallevents when the capacity of the soil pipesis exceeded and pore water pressureincreases rapidly (Uchida et al. 2001). InJapan, pipe outlets were evident in severalof the scars left by landslides that occurredduring heavy rainfall events. These land-slides occurred on various bedrock typesand on slopes that ranged from 20 to 84%(average 51%) (Uchida et al. 2001).

Soil pipes are particularly vulnerable todisturbance because they lie hiddenbeneath the soil surface. Although there isoften minimal surface expression of their

existence, wetter surrounding groundconditions and surface “blowholes” some-times divulge their location. Increases inbulk density and moisture content, anddecreases in hydraulic conductivity andinfiltration, commonly follow forest har-vesting. The collapse and closure ofmacropores and soil pipes from harvest-induced soil compaction is implicated asthe probable cause of higher bulk densityvalues (Herbauts et al. 1996; Miller et al.1996; Williamson and Neilsen 2000).Therefore, before harvesting, it is impor-tant to identify the most hydrologicallyactive zones and their spatial extent andconnectivity within a basin.

After harvesting, and the subsequentincreases in water inputs discussed above,pipeflow will likely play a more importantrole in hillslope hydrology. Actions thatprevent soil pipes from collapsing (e.g.,using slash to dissipate machine load orminimizing the number of machine pass-es) would help preserve their function and connectivity, and maintain hillslopedrainage patterns. New soil pipes presum-ably form after existing ones are damaged,although it remains unclear how long thisprocess takes and to what extent the pipenetwork is restored. Studies of soil pipedynamics should be included in thehydrological monitoring of future oper-ational trials.

3.4.4 Soil water chemistry The uplandscrub forests of the north coast arethought to form a transition between productive upland forests and wetlandforests. In Quebec, Dubé et al. (1995)showed that forest types transitionalbetween upland forest and peatland arethose most susceptible to water table risesafter harvesting. As indicated earlier, how-ever, on the north coast, the water tablerise following harvesting in upland scrubforests is not expected to be as dramatic as in the swamp forests.

High water tables and the high levels of acidity in peatland systems are signifi-cant limitations to the nutrient cycling

46

and forest productivity of these ecosys-tems. Nutrient availability is also limitedby phenolic acids, which inhibit mineral-ization of nitrogen and phosphorus (deMontigny and Weetman 1990), and byhigh concentrations of lignins in cedarfoliar litter (Prescott et al. 1995).

A high water table limits nutrient avail-ability, and thus site fertility (Paavilainenand Päivänen 1995), largely by restrictingrooting depth and often by maintaininganaerobic soil conditions. A high watertable, therefore, controls redox conditionsand the cycling of some important nutri-ent ions. Under aerobic conditions,decomposing soil organic matter releasesnitrogen (N), sulphur (S), and phospho-rus (P), which are oxidized to the ionsNO3, SO4, and PO4, respectively (Devitoand Dillon 1993). During periods of highwater table, anaerobic conditions predom-inate, which prevents the oxidization ofnutrients to available forms. Our studyshows that the highest ion concentrationsin soil water occur in well-drained (pro-ductive forest) vegetation types whichhave deeper water tables and thicker aero-bic zones.

We collected data only in a pre-harvest setting, and have relatively littlepost-harvest data available from similarsettings; therefore, our conclusions arepreliminary. After harvesting, levelscould increase along with the greaterwater inputs to a site (Maloney et al.2002). In addition, concentrationsare likely to rise as logging slash anddebris decomposes, and as microbialactivity increases in the warmer soil(Moore and Jackson 1989). Dissolvedorganic carbon concentrations in streamwaters may remain elevated for up to 8–10 years after harvest, although the resultsfrom other studies in similar settings arevaried (Moore 1989; Moore and Jackson

1989). If increases a large amountafter harvesting, water quality can beaffected in several ways, including:• increased water acidity,• darker water with lower light penetra-

tion, and• increased ability of the water to trans-

port metals (Davies-Colley and Vant1987; Driscoll et al. 1989; Driscoll et al.1995).These changes may potentially lower

drinking water quality and have an unde-sirable effect on aquatic vegetation andfish populations. Dissolved organic car-bon dynamics in pre- and post-harvestconditions requires further monitoring. If harvesting is to occur in sensitive water-sheds where increases in could haveimportant downstream impacts, optionsto minimize these effects (e.g., reducingthe rate of harvesting) should be exam-ined during the planning stages.

A recent study of peatland and non-peatland watersheds in southeast Alaskashowed that peatland-dominated water-sheds had much higher average concentrations in the streams than thenon-peatland watersheds (D. D’Amore,U.S. Department of Agriculture, Juneau,Alaska, pers. comm., Dec. 2004). Theresearchers involved hypothesized that the peatland streams were better adaptedto handle an increase of after harvestthan the non-peatland systems, and thatthe non-peatland systems were more sus-ceptible to changes in stream biologyresulting from increased inputs after harvest.

Future operational trials in lower-productivity western redcedar–hemlockforests should include a soil water moni-toring program. Such a program couldbetter quantify changes in water table levels and ion concentrations in soil andstream waters associated with harvesting.

47

Ecological plot data and field observationssuggest that forest productivity on theouter coast reflects the interactions ofmany site variables, such as soil depth, thenature of surficial organic layers, theunderlying mineral soil, bedrock geology,soil hydrology, slope, and disturbance his-tory. The ecosystem processes componentof the HyP3 Project strives to understandhow and why each of these factors affectsite productivity and how they all interactto yield a specific forest ecosystem. Thisinformation is essential to identify thosesites with potential for timber manage-ment, and to develop treatments that willmaintain or improve site productivity.

Organic matter dynamics, includingrates of forest humus and peat accumula-tion, is an important ecosystem processon the outer coast where organic soil lay-ers play a vital role in determining succes-sional trends and site productivity. Themany peatlands that characterize thecoastal landscape preserve a record of past conditions in their pollen and macro-fossil profiles. These profiles provide thedata against which we can compare cur-rent conditions, and predict future hydro-logical and related ecosystem responses tonatural and human-influenced disturbances.

Core sampling at several sites was con-ducted to reconstruct historical vegetationpattern and rates of peat accumulation.Production and decomposition rates with-in present-day vascular plant and mosscommunities were measured to estimatecurrent rates of accumulation. These stud-ies included detailed measurements ofannual sphagnum moss productivity andcolonization on both disturbed and undis-turbed sites.

HyP3 research also included studies onbedrock, soil properties, and site produc-tivity relationships in both old-growthand second-growth stands across the spec-trum of site series, from bog woodlandand scrub forest, to productive uplandforest. Studies assessing whether sitemanipulations to improve productivityare operationally feasible on lower-productivity wetter sites are also underway and are reported on in Chapter 6.

Finally, a model of ecosystem develop-ment and productivity is presented. Weuse this model to summarize the roles thatbedrock geology, soil drainage, and dis-turbance history play in ecosystem devel-opment in the CWHvh2. This modelrepresents a synthesis of the many indiv-idual findings of this project.

4 ECOSYSTEM PROCESSES

4.1 Introduction

Our research on the role of successionand disturbance in vegetation dynamicswill help to determine whether the lower-productivity western redcedar-dominatedforests of the north coast can be harvestedand regenerated sustainably. Understandingecological processes, such as successionand disturbance, is critical to this determi-nation because of the close ecological rela-tionship between forests and bogs on thenorth coast, and the importance of distur-bance in controlling bog and forest suc-cession.

Ecological succession is defined as thechange in species composition and cover

of plant communities over time, ultimate-ly leading to a climax or relatively stablevegetation type. This process is oftenaccompanied by changes in soil composi-tion and hydrology, which may be initiat-ed by the vegetation itself, especially inwetlands. Bog development is an extremecase where the buildup of organic matterover hundreds or thousands of years (i.e.,paludification) can produce conditionsdetrimental to tree growth. The gentle ter-rain of the Hecate Lowlands on the outernorth coast, with its combination of highlevels of precipitation and low levels ofdisturbance, favours paludification and

4.2 Successionand Disturbance

48

bog development. This process is slowedon steeper terrain, where adequate soildrainage, slope instability, and occasionalwindthrow events tend to retard organicmatter buildup and maintain forest pro-ductivity. Research suggests that sustain-able forestry is only possible on siteswhere the natural inhibition of treegrowth has not progressed too far and willnot be promoted by harvesting practices.This section summarizes the relationshipbetween natural disturbance and succes-sional trends on the north coast.

4.2.1 Successional trends Evidence sug-gests that the plant communities of theouter north coast have long-term succes-sional linkages. Successional historiesspanning thousands of years are recon-structed by analyzing the peat stratigraphyof bogs using pollen, spores, and plantremains in peat cores, and radiocarbon(C14) dating. Cores collected by Banner etal. (1983) near Prince Rupert show an8000-year sequence, from an initial shorepine–red alder pioneer forest, to a Sitkaspruce–western hemlock productive allu-vial forest, then to a western redcedar–yellow-cedar scrub forest, and finally to ashore pine–yellow-cedar–western hemlockbog woodland. Some areas have shownfurther changes from the bog woodland to the open bog stage (Turunen andTurunen 2003). This shift in productivityand biomass allocation from trees tobryophytes appears to represent the domi-nant successional direction on the gentleslopes of the outer north coast. Someareas, however, show productive forestsgrowing over peat deposits, which indi-cates that succession from wetland to for-est also occurs on certain sites (Banner etal. 1983). Based on C14 dating, one suchtransition from wetland peat to uplandforest humus in the Rainbow Lake areanear Prince Rupert began approximately2100 (before present) (Banner et al.1983).

These successional trends highlight animportant difference between the north

coast and other less maritime areas ofBritish Columbia. In most interior ecosys-tems of the province, successional path-ways following disturbance (mainly fire)lead to a climax of productive forest. Onthe outer north coast, however, researchsuggests that the main long-term succes-sional pathway, especially on the subduedlandscape of the Hecate Lowlands, is from upland productive forest to lower-productivity forest types, and eventuallyto open bog (Klinger 1996). This succes-sional pattern is not unique to the north-western coast of North America. Otherhypermaritime areas where sloping blanket bogs are extensive includeNewfoundland, Great Britain, Ireland,Scandinavia, southern Chile, and south-western New Zealand (Moore andBellamy 1974). In the United Kingdom,forest-clearing activities may have playedan important role in the development ofopen blanket bogs over large areas thatwere formerly forested (Moore 1987).

4.2.2 The role of climate in successionBased on studies of peat stratigraphy, evi-dence suggests that a period of peatlandexpansion, triggered by a cooler and wet-ter climatic trend, occurred during themiddle part of the Holocene. Estimates ofwhen this expansion began range from3500 to 6000 (Heusser 1960; Mathewesand Heusser 1981; Banner et al. 1983;Hebda 1995) (Figure 4.1). On the northcoast, this cooler and wetter trend wasevidently sufficient to trigger successionfrom productive forest to scrub forest,thus setting the stage for the developmentof the blanket bog communities that char-acterize much of the area today.

4.2.3 The role of disturbance in succes-sion Natural disturbance events on thenorth coast, as described in Chapter 2,play an important role in slowing andreducing organic matter accumulation onspecific types of sites. The main types ofnatural disturbance on the north coast arelandslides, windthrow, and fluvial activity.

49

These disturbance agents may cause large-scale, catastrophic (stand-replacing) disturbances or more localized gap distur-bances. The churning of soil that occurswhen a root wad is turned up or a land-slide occurs speeds the decomposition ofaccumulated organic materials, bringsmineral soil to the surface, and preventsor reverses hardpan formation (Bormannet al. 1995; Kayahara and Klinka 1997).After a windthrow disturbance, neworganic horizons on the exposed tree rootmounds can form at rates almost on parwith those of long-term peat accumula-tion in peatlands (Bormann et al. 1995;Turunen and Turunen 2003). Withoutregular disturbance, this organic mattercould continue to accumulate to consider-able depths. Studies in southeast Alaskasuggest that a disturbance return period ofless than 200–350 years is needed to pre-vent tree roots from being confined to anincreasingly thick organic horizon(Bormann et al. 1995). Longer disturbancereturn intervals may result in paludific-ation and declining forest productivity.This relationship between disturbance andecosystem productivity has also been

studied in other parts of the world. Thereis growing scientific evidence from tropi-cal, temperate, and boreal zones that anecosystem “decline phase” is associatedwith the long-term absence of catastroph-ic disturbance (Wardle et al. 2004.)

Although most researchers agree thatwindthrow is an important disturbanceagent on the coast, only limited documen-tation (especially for the north coast)exists concerning the extent of occur-rence, return intervals, and the degree towhich windthrow contributes to soil mix-ing across the landscape. A recent study insoutheast Alaska (Hennon and McClellan2003) found that many forests have noevidence of catastrophic windthrow, andthat most tree death leading to canopy gapformation does not involve windthrow, orthe uprooting necessary to cause soil mix-ing. For example, in areas of high windexposure, more than 80% of the canopy-level gap makers were either dead-standingtrees or had snapped off, neither of whichcontribute to soil mixing. In contrast,Bormann et al. (1995) found good evi-dence at several sites in southeast Alaskathat windthrow played an important role

4

3

2

1

0

–1

–2

–3

Tem

per

atur

e (o C

) an

d p

reci

pita

tion

(no

scal

e)

Years BP ('000s)

10 9 8 7 6 5 4 3 2 1 0

Present conditions

Cool wet period

Warm dry period Warm wet period

Relative temperatureRelative precipitation

. Historical climatic conditions on the north coast relative to present conditions(interpreted from Hebda, 1995).

50

in soil mixing and the reversal of paludifi-cation processes. Clearly, these studiesrequire duplication and expansion on thenorth coast of British Columbia to betterquantify the extent and effects of wind-throw as both a small scale and cata-strophic disturbance agent.

4.2.4 Management implicationsSuccessional dynamics on the outer northcoast has implications for forest manage-ment, both in the currently operable, pro-ductive forests and the lower-productivitywestern redcedar-dominated scrub forests,where little harvesting has occurred to date.

On the productive, currently operablesites, activities such as suspension cablelogging and helicopter logging, whichminimize surface disturbance and pro-mote the development of young wind-throw-resistant stands, may result indeclining forest productivity over time. In this case, forest harvesting could act tolengthen the disturbance-return interval,and thereby reduce mineral soil distur-bance, allowing organic matter to accu-mulate without the setbacks caused bywindthrow-induced mixing of mineraland organic horizons (Bormann et al.1995). This lack of disturbance could setthe forest on a trajectory of organic matteraccumulation that would be difficult toalter, especially where forests are managedon shorter rotations (≤ 100 years) whichpre-empt the natural windthrow distur-bance cycle.

On steep slopes susceptible to masswasting (e.g., landslides, and debris flows),however, forest harvesting and road build-ing may promote excessive disturbancewith potentially negative effects on pro-ductivity, especially in the short term (seeFigure 1.4). Studies on Haida Gwaii /theQueen Charlotte Islands show that timberharvesting can leave hillslopes susceptibleto accelerated rates of mass wasting for15–20 years following harvesting, or untilstabilizing root systems re-establish. Acomparison of mass wasting rates on thesteep west coast of the Queen Charlotte

Islands revealed a 15 times greater rate ofoccurrence on human-modified terrainthan on forested terrain (Banner et al.1989). The effects were greatest in areas oflarge clearcuts and road networks. In thenatural forest landscape, mass wastingevents are spread out in time and space,and are partially responsible for maintain-ing forest productivity. Where landslideactivity is accelerated by human activities,however, negative effects often result, suchas regeneration delays, initial loss of pro-ductivity near the slide source where soilis scoured to bedrock, and sediment load-ing and scouring of aquatic habitat. Thesevery visible and immediate impacts tendto outweigh any potential improvement to long-term productivity that may occurin downslope areas. One of the majorchallenges we face is managing human-induced disturbances on a site-specificbasis and in a way that attempts to mimicthe natural system. Another challenge isgaining public acceptance that distur-bances, whether natural or human-induced, can have positive as well asnegative impacts on ecosystems.

In the lower-productivity forests thathave escaped major disturbance events forthousands of years, harvesting and sitepreparation activities may provide thenecessary surface disturbance and soilchurning to mix mineral and organichorizons, improve nutrient availabilityand soil aeration, and retard organic mat-ter accumulation. Given the appropriatesite conditions (i.e., surface organic hori-zons underlain by mineral soil), suchactivities may improve tree productivity.This mixing may not be possible orbeneficial, however, on sites with deeporganic soils, or where mineral soils arevery shallow or absent. Differences in soilproperties and site productivity oftenreflect differences in bedrock geology.Mineral soils are often thinner over hard,massive granitic rocks than over softermetamorphic rocks, especially the schists(see section 4.5.1 for more detail). If tim-ber harvesting expands into these lower-

51

productivity forests, candidate sites mustbe carefully assessed using specific site and stand criteria so that any treatmentsapplied will ensure acceptable second-

growth regeneration and productivity. See Chapter 6 for details about the treat-ments applied in operational trials nearPrince Rupert.

One of the most significant concernsregarding forest harvesting activities onlower-productivity, western redcedar-dominated sites is site degradation andreduced forest productivity. This concernis particularly relevant in north coastalBritish Columbia because paludificationappears to have extended wetlands intoformerly productive forests (Banner et al.1983). Paludification is influenced by sev-eral factors including soil physical andchemical properties, long-term plant suc-cession, and climatic changes. In severalparts of the world, human activities, suchas forest clearing and agriculture, also playa role in promoting paludification (Moore1987; Warner et al. 1989). Forest clearingremoves the rain-intercepting canopy anddecreases evapotranspiration. This maycause a rise in the water table, facilitatethe invasion by peat-forming sphagnummosses, and potentially retard decomposi-tion in saturated organic horizons.

Mosses are a major component of thevegetation in the hypermaritime, and peataccumulations are composed primarily ofthe remains of mosses mixed with sedgesand other vascular plants. The response ofmosses to forest management practices isof interest because of possible interactionswith forest productivity and long-termvegetation successional pathways. Peataccumulates when moss productionexceeds decomposition rates. To deter-mine the peat accumulation potential ofan area, measurements of productivityand decomposition rates are necessary.Acquiring this baseline information fornatural peatlands will be useful for com-parisons with managed areas.

Site preparation following harvestingmay further promote the invasion ofsphagnum mosses. Throughout BritishColumbia and in many other areas,

mounding is used in wet forests to pro-duce plantable sites, and to increase treesurvival and growth (Londo 2001; Shawand Banner 2001a). This treatment, how-ever, can result in adjacent wet depres-sions, which may facilitate the invasion ofsphagnum mosses and the paludificationof previously forested ecosystems; there-fore, it is imperative to understand theecological relationship between mossgrowth and forest dynamics, and how thisrelationship is affected by forest manage-ment practices.

To create a more complete picture of how plant species, climate, micro-topography, and ultimately site productiv-ity interact on the scrub forest sites of thenorth coast, this section summarizesinformation from Asada (2002), Asada etal. (2003a, 2003b), Asada et al. (2004), andAsada and Warner (2005). It describes aseries of experiments carried out at theDiana Lake and Port Simpson study sites(Figure 2.9) that deal with moss ecology,paludification, and vegetation and envi-ronment relationships. These experimentsset out to:• provide quantitative estimates of the

growth and production of mosses andpeatland community types on the outercoast of British Columbia;

• compare decomposition rates in differ-ent community types;

• document vegetation and environmentrelationships in natural and post-harvest communities;

• examine the possible effects of forestmanagement practices on moss growthand productivity; and

• examine the effect of harvesting andmounding activities on vegetation,especially sphagnum mosses, at the PortSimpson operational trial.

4.3 Paludificationand Vegetation

Dynamics

52

4.3.1 Study approach Each of the studyareas required a baseline classification ofvegetation communities to provide aframework for further vegetation andenvironment studies. The cover of allplant species was recorded in quadratsalong transects within the Diana Lake and Port Simpson study sites. Thesequadrats were grouped by classificationanalysis (Two-Way INdicator SPeciesANalysis – ; Hill 1979) intoplant communities for each study area.Multivariate ordination analyses (detrend-ed correspondence analysis [] andcanonical correspondence analysis [];Hill and Gauch 1980; ter Braak 1986)revealed the relationship between theresulting plant communities and the envi-ronment.7 Environmental variablesincluded water table and water chemistrymeasures, physical soil property measures,and slope. The Port Simpson study wasconducted 8 years after harvesting and sitepreparation treatments. As no comparablepre-harvest data existed for the plantcommunities there, those of Diana Lake

were examined to determine the likelychanges at the harvested Port Simpsonsite.

Moss productivity was determinedusing nine abundant moss species at theDiana Lake site: Sphagnum austinii(Austin’s peat-moss), S. fuscum (commonbrown peat-moss), S. rubellum, S. papillo-sum (fat peat-moss), S. lindbergii (brown-stemmed peat-moss), S. tenellum (softpeat-moss), S. pacificum, Racomitriumlanuginosum (hoary rock-moss), andPleurozium schreberi (red-stemmed feath-ermoss). The selected mosses are the mostrepresentative peatland species in theregion and have fairly specific habitatpreferences (Table 4.1). Their growth wasmeasured periodically and compared withlocal climatic parameters.

Growth measurements for all specieswere made at approximately 2-week intervals from May through August in1999, and again on November 19, 1999.Measurements for R. lanuginosum and P.schreberi were also taken on July 11, 2000,and again on June 5, 2001. Winter growth

7 Refer to Asada et al. (2003b) for further details on classification and ordination approaches used in this study.

. Growth and production of sphagnum and other mosses and their correlation with climatic parameters (adapted fromAsada et al. 2003a)

Correlation Correlation Correlationwith mean with mean with

Productiona daily daily ClimaticSpecies Habitat preference Growtha (mm) (g/m2) precipitationb temperature Indexb

Sphagnum austinii Large hummock 10 ± 3c 280 ± 80a 0.15 0.03 0.35S. fuscum Large hummock 16 ± 4b 310 ± 70a 0.60 –0.24 0.72*S. rubellum Small hummock 15 ± 3b 220 ± 50ab 0.85** –0.60 0.81*S. papillosum Wet hummock 21 ± 4b 150 ± 50ab 0.75* –0.38 0.76*S. tenellum Around pools and wet lawns 15 ± 4b 110 ± 40ab 0.84** –0.39 0.88**S. pacificum Wet lawns 52 ± 9a 230 ± 50ab 0.74* –0.30 0.88**S. lindbergii Depressions and small streams 43 ± 11a 260 ± 80a 0.73* –0.27 0.82*Racomitrium Dry mounds in bog 9 ± 1–10 ± 1 360 ± 40–410 ± 50 0.59 0.18 0.95**

lanuginosumPleurozium schreberi Bog woodland 20 ± 2–23 ± 3 290 ± 60–320 ± 80 0.47 0.25 0.89**

a Growth and production for sphagnum mosses was estimated from May 21 to November 18, 1999; for other mosses the first-year growth(i.e., 1st number) is from July 16, 1999 to July 11, 2000, and the second-year growth (i.e., 2nd number) is from July 11, 2000 to June 5, 2001.Values are means ± standard error. Means followed by a different letter are significantly different (Tukey’s HSD, p < 0.05, tested among sphagnum mosses only).

b Correlation between moss growth and climatic parameters is shown using Pearson correlation coefficients (*p < 0.05; **p < 0.01).

53

measurements for sphagnum species wereimpossible because of interference fromsnow; therefore, winter growth was esti-mated by using the relationship betweenthe growth and the climate derived fromthe climatic index (described below).Estimated winter growth was added tosummer growth to obtain estimates ofannual growth; however, winter growthestimates do not take into account solarradiation differences between summerand winter. Other concerns about esti-mates of winter sphagnum growth areoutlined in Asada et al. 2003a.

The climatic index produces a regres-sion equation for each sphagnum species,and the winter growth was then estimatedby inserting winter climate data into theequation. Note that the estimated valuesfor hummock-forming sphagnum speciesshould be treated with caution becausethe correlation coefficients between thegrowth and the climatic index, thoughhigh, were not significant. Annual pro-duction of each moss per unit area wasestimated by multiplying the averageannual linear growth by the average massper unit length (Table 4.1).

To quantify concerns about paludi-fication, the growth rates of three sphag-num species (S. pacificum, S. rubiginosum,and S. rubellum) were measured at PortSimpson and compared with those inunharvested areas at Diana Lake. Snowcompression led to problems in measur-ing sphagnum growth; the maximumgrowth values were considered more accu-rate than mean values, and were thereforeused for comparison purposes. In addi-tion, the annual changes in area and volume covered by mosses, especiallysphagnum, were measured at three PortSimpson locations.

Daily precipitation, and daily mean,maximum, and minimum temperatureswere obtained from the meteorologicalstation in the open bog of the Diana Lakesite. These climate variables were treatedas single parameters and also combinedfor the climate index. The climate index

was developed to reflect the followingassumptions, which were expected fromprevious studies:• Growth of mosses is controlled prim-

arily by precipitation.• Precipitation cannot contribute to the

moss growth if temperatures are lowerthan a certain threshold.

• The higher the temperature (up tomoderate temperatures), the more pre-cipitation relates to growth.The climatic index adjusts the precipi-

tation for each day by the temperature forthat day. When the temperature is lowerthan a set threshold, the amount of pre-cipitation is adjusted to zero, while pre-cipitation on warmer days receives anincreased weighting, based on the numberof degrees above the threshold.

Moss growth and all climate parame-ters were expressed as means per day in agiven period. Correlation coefficientsbetween the growth and each climateparameter (i.e., precipitation, tempera-ture, and climatic index) were calculatedfor each species. See Asada et al. (2003a)for a more detailed description and math-ematical formula for the climatic index.

Measurements of current year’s growthfor the major herb, shrub, and lichenspecies, and the moss productivity datadescribed above, were used to determineecosystem productivity in the five com-munity types found in the open peatlandat Diana Lake (Asada 2002). Below-ground productivity was estimated using root to shoot ratios found in other studies. The productivity of the entirepeatland was estimated by applying aweighting to the production by the per-cent cover of each community type withinthe peatland. To estimate long- and short-term peat accumulation rates, radiocar-bon and 210Pb dating techniques wereapplied to surface cores collected from the Diana Lake study site (Turunen andTurunen 2003; Asada and Warner 2005).

The decomposition rate of organicmaterial (Sphagnum fuscum was used as astandard material) was measured in nine

54

plant communities at Diana Lake (e.g.,bog woodland, bog forest, scrub forest,upland forest, and open peatland, whichwas further subdivided into five commu-nity types) and the four plant communi-ties that were identified at Port Simpson.Organic matter placed in mesh bags wasburied at a 10 cm depth in all plant com-munities, and also at a 25 and 45 cm depthin the bog woodland and open peatland atDiana Lake. Bags were removed after 1and 2 years of incubation, and analyzedfor mass loss and changes in carbon andnitrogen content.

4.3.2 Results: plant communities The classification of quadrats atthe Diana Lake research site identifiednine plant communities. These communi-ties were analogous to some of the siteseries identified by Banner et al. (1993)(see section 5.2), except that the open bogcommunity was further subdivided intofive sub-communities (Table 4.2). Siteseries at Diana Lake include: Westernhemlock – Sitka spruce – Lanky moss(CWHvh2/04–productive forest), Westernredcedar – Western hemlock – Salal(CWHvh2/01–scrub forest), Yellow-cedar– Western redcedar – Goldthread(CWHvh2/11–bog forest), Shore pine –Yellow-cedar – Sphagnum (CWHvh2/12–bog woodland), and Non-forested slope –blanket bog (CWHvh2/32); sub-commu-nities identified within the open bogs wereMenyanthes trifoliata pool, Carex utricula-ta – Sphagnum lindbergii depression,Rhynchospora alba – S. tenellum lawn,Racomitrium lanuginosum hummock, andS. austinii hummock.

An ordination of sample plots from theabove plant communities is presented inFigure 4.2. Sample plots of similar speciescomposition and cover are clustered onthis graph. The distribution of plant com-munities on axis 1 correlated best with the minimum level of groundwater tablefluctuation and slope. For example, openbog communities were found in areas oflittle slope and high water table, and

forested communities were found in areasof greater slope and (at least seasonally)lower water tables. Although these twoparameters are interrelated, steepness ofslope influenced site drainage and soilwater flux, and the water table influencedaerobic soil conditions and water chem-istry. The distribution of productive forest(CWHvh2/04) on axis 2 correlated withthe maximum level of groundwater tablefluctuation and higher soil water conduc-tivity parameters. This plant communitygrows in areas with consistently gooddrainage and is more influenced bygroundwater in contact with mineral soils.

At the Port Simpson operational trial site, four plant communities wereidentified: two were related to wet hollows (Sphagnum angustifolium and S. pacificum); one was related to relativelydry (mesic) mounds (Cornus canadensis –Hylocomium splendens); and one wasintermediate in moisture (Polytrichum for-mosum – Sphagnum girgensohnii) (Table4.3). The unmounded area contained onlyone plant community that is generallyrelated to mesic areas—Cornus canadensis– Hylocomium splendens. The moundedarea contained a mixture of all four com-munities, reflecting the altered micro-topography created by the moundingtreatment.

The plant communities associated withthe mesic mound and the intermediatemoisture areas at Port Simpson were simi-lar to those of the natural forest site atDiana Lake, while the two sphagnum-dominated communities were very differ-ent from those at Diana Lake. Thissuggests that the species in these commu-nities are responding to habitat changesinduced by forest management; the twosphagnum species that dominate the wethollows are not commonly found inforested areas and therefore likely colo-nized the site after harvesting. Thesesphagnum-dominated communities werelocated mainly in fens in the larger DianaLake area. A paleoecological study

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. Vegetation classified at the Diana Lake study site by Two-Way INdicator SPecies ANalysis (TWINSPAN) (adapted fromAsada et al., 2003b)

Communitya C1 C2 C3 C4 C5 C6 C7 C8 C9Number of plots 3 5 5 11 5 9 14 9 5

Species name Stratumb

TreesAbies amabilis (Dougl. ex Loud.) Dougl. ex Forbes 9 5.0c – – – – – – – –

8 0.7 0.6 – – – – – – –7 1.7 – – – – – – – –6 1.7 – – – – – – – –5 1.3 – – – – – – – –4 2.0 – – – – – – – –

Tsuga heterophylla (Raf.) Sarg. 9 5.0 – – – – – – – –8 3.3 3.6 – – – – – – –7 2.3 4.0 0.8 0.3 – – – – –6 3.7 3.8 2.4 0.3 – – – – –5 2.0 – 1.2 – – – – – –4 1.7 0.4 – – – – – – –

Picea sitchensis (Bong.) Carr. 9 – 0.6 – – – – – – –8 – 0.8 – – – – – – –7 – 1.2 – – – – – – –6 – 1.2 – – – – – – –5 – 0.4 – – – – – – –

Tsuga mertensiana (Bong.) Carr. 8 – 2.6 – – – – – – –7 – 1.0 1.8 – – – – – –6 – – 1.2 – – – – – –5 – 0.2 0.8 – – – – – –

Thuja plicata Donn ex D. Don 9 2.3 1.6 – – – – – – –8 – 4.4 0.4 – – – – – –7 – 2.6 2.2 – – – – – –6 – 1.2 0.6 – – – – – –5 – 0.2 1.6 – – – – – –4 – 0.6 – – – – – – –

Chamaecyparis nootkatensis (D. Don) Spach 8 – 1.6 1.0 – – – – – –7 – 1.4 2.8 – – – – – –6 – 0.4 2.6 – – – – – –5 – – 3.2 2.2 – 0.4 – – –4 – 1.0 3.2 1.0 1.0 – – – –

Pinus contorta Dougl. ex Loud. var. contorta 8 – – 1.4 – – – – – –7 – – 3.0 0.9 – – – – –6 – – 0.2 1.7 – 0.4 – – –5 – – 1.4 – – 0.7 – – –4 – – – 0.3 – 0.6 – – –

ShrubsVaccinium parvifolium Sm. 6 3.3 0.2 – – – – – – –

5 0.7 0.6 0.8 – – – – – –4 1.7 1.0 0.8 – – – – – –

Oplopanax horridus (Smith) Miq. 6 1.0 0.8 – – – – – – –5 0.3 0.2 – – – – – – –4 0.7 – – – – – – – –

Vaccinium alaskaense Howell 6 2.0 4.0 – – – – – – –5 1.0 0.6 1.2 – – – – – –4 0.3 1.8 1.0 – – – – – –

56

ShrubsMenziesia ferruginea Sm. 6 – 4.0 1.2 – – – – – –

5 1.7 – 1.0 – – – – – –4 – 0.6 0.4 – – – – – –

Vaccinium ovalifolium Sm. 6 – 1.8 – – – – – – –5 – 1.0 1.4 – – – – – –4 – 0.4 – – – – – – –

Gaultheria shallon Pursh 5 – 2.6 0.6 0.2 – – – – –4 – 2.0 3.4 0.3 – – – – –

Ledum groenlandicum Oeder 4 – – 2.0 1.5 1.4 1.2 0.1 0.1 –Myrica gale L. 5 – – – 0.3 – – – – –

4 – – – 0.5 – – – – –Vaccinium uliginosum L. 4 – – 0.4 1.5 0.4 1.3 0.1 – –Juniperus communis L. 4 – – – 1.1 0.8 1.3 0.1 – –Kalmia microphylla (Hook.) Heller occidentalis 4 – – 1.4 1.5 1.0 1.9 0.3 0.8 –

(Small) Taylor & MacBryde

Herbs and Dwarf ShrubsCornus canadensis L. 3 2.3 3.4 3.4 1.5 1.2 1.1 – 0.1 –Tiarella trifoliata L. 2 1.7 – – – – – – – –Rubus pedatus J. E. Sm. 3 1.0 1.8 0.2 – – – – – –Listera cordata (L.) R. Br. 2 0.7 1.0 0.4 – – – – – –Streptopus lanceolatus (Ait.) Reveal var curvipes 2 0.3 0.8 0.4 – – – – – –

(Vail) Reveal.Lysichiton americanus Hult. & St. John 2 – 2.2 – – – – – – –Moneses uniflora (L.) A. Gray 2 – 0.4 – – – – – – –Linnaea borealis L. 3 – 1.6 1.4 0.5 – – – – –Coptis aspleniifolia Salisb. 2 – 1.6 1.8 0.1 – – – – –Vaccinium vitis–idaea L. ssp. minus (Lodd.) Hult. 3 – – 1.4 0.4 – – – – –Vaccinium caespitosum Michx. 3 – – 1.8 – – – – – –

4 – – 1.4 0.3 0.2 – – – –Fauria crista–galli (Menzies ex Hook.) Makino 2 – 0.4 3.8 3.2 0.4 – – – –Rubus chamaemorus L. 3 – – 0.2 0.6 0.8 – – – –Oxycoccus oxycoccus (L.) MacM. 3 – – 0.2 1.0 0.6 0.6 0.1 0.4 –Sanguisorba officinalis L. 2 – – 1.2 2.1 0.4 2.0 0.6 1.4 0.2Drosera rotundifolia L. 2 – – 1.0 2.2 2.0 0.6 2.9 2.0 –Empetrum nigrum L. 3 – – 1.0 1.8 1.8 0.9 0.1 – –Trientalis europaea L. ssp. arctica (Fisch. ex Hult.) Hult. 2 – – 0.4 0.8 0.2 0.7 0.1 0.2Andromeda polifolia L. 3 – – 0.2 1.0 0.6 1.4 1.1 1.1 –Trichophorum cespitosum (L.) Hartm. 2 – – 0.2 1.7 1.2 2.0 0.1 1.0 –Eriophorum angustifolium Honck. 2 – – 0.2 1.4 0.2 1.7 1.1 1.0 3.0Coptis trifolia (L.) Salisb. 2 – – 0.2 1.1 0.4 0.8 – 0.2 –Carex livida (Wahlenb.) Willd. var. radicaulis Paine 2 – – 0.2 0.7 0.2 0.1 – 1.0 1.0Rhynchospora alba (L.) Vahl 2 – – – 0.9 – 1.6 3.4 1.6 1.2Triantha glutinosa (Michx.)Baker 2 – – – 0.7 0.4 – 0.1 0.2 –Carex pauciflora Lightf. 2 – – – 0.5 – 0.1 – 0.6 –Gentiana douglasiana Bong. 2 – – – 0.4 – 0.6 – 0.2 –Dodecatheon jeffreyi van Houtte 2 – – – 0.3 – – – 0.8 –Geum calthifolium Menzies ex J. M. Smith 2 – – – 0.2 – – 0.1 0.6 –

. Continued



57

Herbs and Dwarf ShrubsAgrostis aequivalvis (Trin.) Trin. 2 – – – 0.2 – 0.1 – 0.3 –Drosera anglica Huds. 2 – – – – 1.0 0.1 2.7 0.4 –Carex pluriflora Hult. 2 – – – – – 0.2 0.2 0.9 0.8Carex utriculata Boott 2 – – – – – 0.1 – 2.2 0.2Scheuchzeria palustris L. ssp. americana (Fern.) Hult. 2 – – – – – – 0.3 0.1 0.2Menyanthes trifoliata L. 2 – – – – – – – 0.9 4.6

Ferns / ClubmossesGymnocarpium dryopteris (L.) Newman 2 1.3 – – – – – – – –Polystichum munitum (Kaulf.) K.B. Presl 2 0.7 – – – – – – – –Blechnum spicant (L.) Roth 2 1.3 1.6 – – – – – – –Lycopodium annotinum L. 2 – 0.4 1.2 0.4 – – – – –

BryophytesRhytidiadelphus loreus (Hedw.) Warnst. 1 4.7 2.4 3.0 0.2 – – – – –Rhizomnium glabrescens (Kindb.) T. Kop 1 2.7 1.8 1.6 – – – – – –Hylocomium splendens (Hedw.) Schimp. 1 2.7 4.2 3.0 0.1 – – – – –Eurhynchium oreganum (Sull.) Jaeg. 1 2.3 0.2 – – – – – – –Sphagnum rubiginosum Flatb. 1 1.7 4.0 – – – – – – –Scapania bolanderi Aust. 1 1.3 0.2 – – – – – – –Plagiothecium undulatum (Hedw.) Schimp. 1 1.0 1.0 0.8 0.1 – – – – –Plagiochila porelloides (Torr. ex Nees) Lindenb 1 0.7 1.0 0.2 – – – – – –Riccardia latifrons Lindb. 1 0.3 0.2 – – – – – – –Hookeria lucens (Hedw.) Sm. 1 0.3 0.8 – – – – – – –Sphagnum pacificum Flatb. 1 – 2.6 3.2 1.7 – – – – –Pellia neesiana (Gott.) Limpr. 1 – 1.0 0.2 – – – – – –Sphagnum papillosum Lindb. 1 – 0.4 0.2 1.0 – 1.0 1.1 2.2 –Sphagnum magellanicum Brid. 1 – 0.4 – 0.2 – – – – –Calypogija sphagnicola (H. Arnell & J. Perss.) 1 – 0.4 – 0.1 – – – – –

Warnst. & LoeskeSphagnum capillifolium (Ehrh.) Hedw. 1 – 0.2 2.6 1.5 – – – – –Pleurozium schreberi (Brid.) Mitt. 1 – – 3.0 1.5 – – – – –Sphagnum rubellum Wils. 1 – – 1.8 2.5 1.6 1.4 0.9 0.7 –Sphagnum fuscum (Schimp.) Klinggr. 1 – – 1.6 3.2 1.0 1.6 0.4 – –Bazzania trilobata (L.) S. Gray 1 – – 1.6 0.3 – – 0.1 – –Sphagnum tenellum (Brid.) Bory 1 – – 1.0 0.5 – 0.7 3.4 1.1 –Hypnum callichroum Funck ex Brid. 1 – – 1.0 – – – – – –Hepatophyta (Jungermanniales) spp. 1 – – 0.8 – – – – – –Dicranum majus Sm. var. majus 1 – – 0.8 – – – – – –Ptilium crista–castrensis (Hedw.) De Not. 1 – – 0.4 0.5 – – 0.1 – –Aulacomnium palustre (Hedw.) Schwaegr. 1 – – 0.4 – – – – – –Sphagnum recurvum P. Beauv. 1 – – 0.2 0.5 – – – – –Mylia anomala (Hook.) S. Gray 1 – – 0.2 0.8 0.2 0.1 0.2 – –Racomitrium lanuginosum (Hedw.) Brid. 1 – – – 0.3 – 3.0 0.4 0.6 –Sphagnum austinii Sull. 1 – – – – 5.0 0.7 – – –

. Continued



58

Shore pine – Yellow-cedar – Sphagnum woodland

Yellow-cedar – Western redcedar – Goldthread forest

Western redcedar – Western hemlock – Salal forest

Western hemlock – Sitka spruce – Lanky moss forest

Menyanthes trifoliata pool

Carex utriculata – Sphagnum lindbergii depression

Rhynchospora alba – Sphagnum tenellum lawn

Racomitrium lanuginosum hummock

Sphagnum austinii hummock

2 SI

XA

AXIS 1– 1.0 +1.0

– 1.

0+

1.0

GWTMN

SLOPE

CONMN

CONMX

GWT MX

PHMD

OC10

Enviromental variables abbreviated as follows:

CONMN – conductivity, minimum level of fluctuation

CONMX – conductivity, maximum level of fluctuation

GWTMN – groundwater table, minimum level of fluctuation

GWTMX – groundwater table, maximum level of fluctuation

PHMD – pH, median level of fluctuation

SLOPE – slope

OC10 – soil organic matter content at 10 cm below ground surface

. Canonical correspondence analysis of Diana Lake study plots. TWINSPAN (Two-Way INdicator SPeciesANalysis) communities (described in Table 4.2) are superimposed (adapted from Asada et al., 2003b).

BryophytesSphagnum compactum DC. 1 – – – – – 0.1 0.4 0.7 –Sphagnum lindbergii Schimp. 1 – – – – – – 0.3 2.8 –Scapania undulata (L.) Dum. 1 – – – – – – – 0.3 –

LichensCladina portentosa ssp. pacifica (Ahti) Ahti 1 – – 1.0 2.5 2.0 3.2 1.7 0.8 –Siphula ceratites (Wahlenb.) Fr. 1 – – – – – – 2.4 – –

a C1 = Western hemlock – Sitka spruce – Lanky moss (CWHvh2/04–productive forest); C2 = Western redcedar – Western hemlock – Salal (CWHvh2/01–scrub forest); C3 = Yellow-cedar – Western redcedar – Goldthread (CWHvh2/11–bog forest); C4 = Shore pine –Yellow-cedar – Sphagnum (CWHvh2/12–bog woodland). C5–C9 are sub-communities in the Sphagnum open peatland (CWHvh2/32): C5 = Sphagnum austinii hummock; C6 = Racomitrium lanuginosum hummock; C7 = Rhynchospora alba – Sphagnum tenellum lawn; C8 = Carex utriculata – Sphagnum lindbergii depression; and C9 = Menyanthes trifoliata pool.

b Numbers in the stratum column denote the stratum in which the species are categorized: 1 = bryophyte/lichen stratum; 2 = herb stratum;3 = dwarf shrub stratum; 4 = low shrub stratum; 5 = shrub stratum; 6 = tall shrub stratum; 7 = tree stratum; 8 = tall tree stratum; and 9 = very tall tree stratum.

c Values are means of categories of abundance within each community type. Only species whose values are greater than 0.2 in any community are listed.

. Concluded



59

. Vegetation classified at the Port Simpson study site by Two-Way INdicator SPecies ANalysis(TWINSPAN) (adapted from Asada et al., 2004)

Communitya

(# of plots)P1 P2 P3 P4

Species (18) (76) (156) (27)

Shrubs and seedlingsVaccinium alaskaense Howell 0.3b – 0.2 –Menziesia ferruginea Sm. 0.2 1.2 1.4 –Gaultheria shallon Pursh 0.1 0.6 1.8 0.4Tsuga heterophylla (Raf.) Sarg. – 0.4 0.2 –Vaccinium ovalifolium Sm. – 0.3 0.3 –Thuja plicata Donn ex D. Don – – 0.2 0.1

HerbsLysichiton americanus Hult. & St. John 0.4 0.1 0.1 0.4Maianthemum dilatatum (A. Wood) Nels. & J. F. Macbr. 0.3 0.5 2.6 0.1Cornus canadensis L. 0.1 0.7 2.9 0.1Rubus pedatus J.E. Sm. – 0.3 0.4 0.1Linnaea borealis L. – 0.1 2.0 –Dryopteris expansa (K.B. Presl) Fraser-Jenkins & Jermy – 0.1 0.2 –Coptis aspleniifolia Salisb. – – 0.6 –Blechnum spicant (L.) Roth – – 0.5 –Schoenoplectus tabernaemontani (K. C. Gmel.) Palla – – – 0.2

BryophytesSphagnum angustifolium (C. Jens. ex Russ.) C. Jens. 2.6 0.1 0.2 0.2Polytrichum formosum Hedw. 1.5 2.8 0.5 0.4Dicranum fuscescens Turn. var. fuscescens 1.4 0.3 0.1 –Sphagnum palustre L. 0.8 0.2 0.0 –Sphagnum tenerum Sull. & Lesq. 0.5 0.0 – –Sphagnum rubellum Wils. 0.4 0.3 0.3 0.1Sphagnum girgensohnii Russ. 0.2 1.3 0.6 0.3Polytrichum juniperinum Hedw. 0.2 0.1 0.2 –Cephalozia bicuspidata (L.) Dum. ssp. bicuspidata 0.1 0.5 0.1 –Dicranella heteromalla (Hedw.) Schimp. 0.1 1.1 0.6 –Plagiothecium undulatum (Hedw.) Schimp. 0.1 0.3 0.5 –Scapania bolanderi Aust. 0.1 0.8 1.1 –Rhytidiadelphus loreus (Hedw.) Warnst. 0.1 0.7 1.8 –Hylocomium splendens (Hedw.) Schimp. 0.1 0.4 2.5 –Sphagnum pacificum Flatb. – 0.6 0.3 4.9Pogonatum dentatum (Brid.) Brid. – 0.3 – –Lophozia cf. wenzelii (Nees) Steph. var. wenzelii – 0.3 0.1 –Sphagnum capillifolium (Ehrh.) Hedw. – 0.1 0.6 –Pleurozium schreberi (Brid.) Mitt. – – 0.2 –Barbilophozia floerkei (Web. & Mohr) Loeske var. floerkei – – 0.2 –Dicranum scoparium Hedw. – – 0.3 –Calypogeja muelleriana (Schiffn.) K.Müll. ssp. muelleriana – – 0.3 –

a P1: Sphagnum angustifolium community; P2: Polytrichum formosum – Sphagnum girgensohnii community;P3: Cornus canadensis – Hylocomium splendens community; and P4: Sphagnum pacificum community.

b Values are means of categories of abundance within each community defined by pseudospecies cut levelsof TWINSPAN. Values are rounded to 0.1, and only species whose values are greater than 0.1 in any commu-nity are listed.

60

(Turunen and Turunen 2003) showed thatone of these areas had undergone palud-ification relatively recently, which helps toconfirm the pioneering capacity of S.pacificum and S. angustifolium in naturalsystems, as well.

The multivariate ordination analysis ofthe relationship between environmentalvariables and plant communities showedthat the distribution of these communitiescorrelated best with water table depth;pH, conductivity, and slope showed up assecondary factors. This indicates that theplants respond mainly to soil moistureand related conditions. Pools formed bythe mounding, possibly in combinationwith a post-harvest rise in water table,appear to provide habitat conditions thatallow colonization by these species (Figure4.3). The acidifying ability of sphagnumlikely creates water chemistry gradients(i.e., pH and conductivity); these gradi-ents, in turn, facilitate additional sphag-num growth and limit the potential forvascular plant establishment and growth(van Breeman 1995).

Sphagnum rubiginosum, and the taxonomically closely related species,Sphagnum girgensohnii, commonly inhabitforested areas and occur at both the PortSimpson and Diana Lake sites. At PortSimpson, however, these species weremore abundant in the mounded portion of the harvested area than in the unmounded portion. The presence of pools in the mounded area is likelyresponsible for the persistence of thesespecies, which are often associated withthe pits formed by blowdowns in the for-est (Noble et al. 1984). In addition, S.pacificum and S. angustifolium, which are closely related to known pioneeringspecies such as S. fallax (Grosvernier et al.1997; Buttler et al. 1998), likely colonizedthe hollows created by the moundingprocess after harvesting. Mounding as asite preparation treatment appears, there-fore, to facilitate the persistence or colo-nization of several sphagnum species.

. Depressions created by mounding at Port Simpson filled in with sphagnum moss after 6 years.

61

4.3.3 Moss growth and climate parame-ters Figures 4.4 and 4.5 illustrate thegrowth patterns of Pleurozium schreberiand four of the sphagnum species studiedin relation to climatic parameters. For thesphagnums, the hollow and the wet lawnspecies (i.e., S. lindbergii and S. pacificum)grew more than the hummock-formingspecies (i.e., S. austinii and S. fuscum)(Figure 4.5); however, the growth rates ofthe hummock-forming species were lessvariable than the hollow and the wet lawnspecies. Hummock species grew even dur-ing the dry period, albeit slowly, but thehollow and lawn species did not.

Generally, the growth pattern ofRacomitrium lanuginosum, P. schreberi(these two species showed very similargrowth patterns), and the seven sphag-num species reflected the precipitationpattern rather than that of temperature(Figures 4.4 and 4.5). Correlationcoefficients between precipitation andgrowth were higher than those betweentemperature and growth for all species(Table 4.1), and five species showed statistically significant correlations.

The climatic index showed a muchhigher correlation with growth than either precipitation or temperature alonefor all species except S. rubellum (Figures4.4 and 4.5; Table 4.1). Growth wassignificantly correlated with the climaticindex for all of the species except S. austinii.

When the lowest temperature abovewhich vegetative growth occurs is used asthe exploratory temperature threshold inthe index, the climatic index should havethe highest correlation with moss growth.Correlation coefficients for the growth of R. lanuginosum and P. schreberi werehighest with the climatic index when dailymean temperature was set at 5°C, whichimplies that this is the temperaturethreshold for the growth of these twospecies. For the sphagnum species, thehighest correlation with the climatic indexwas at 0°C for most species, 5°C lowerthan that for R. lanuginosum and P.

schreberi. These growth threshold temper-atures are preliminary, however, becauseof difficulties in obtaining winter growthmeasurements. See Asada et al. (2003a) formore detail on the estimation methods fortemperature thresholds.

At Diana Lake, Sphagnum pacificumwas the fastest-growing species (i.e., verti-cal stem growth), with an estimatedgrowth of 52 mm between May andNovember 1999 (Table 4.1); S. lindbergiialso had rapid stem growth of 43 mm dur-ing the same period. S. austinii had theslowest growth rate, which was estimatedat 10 mm. S. fuscum, S. rubellum, and S.tenellum showed similar growth rates ofabout 15 mm.

The most productive sphagnum species(total annual biomass) were the hum-mock-forming S. fuscum and S. austinii(Table 4.1). Although the vertical growthof the hummock species was small, theirdense growth form contributed to thishigh productivity. In particular, the bulkdensity of S. austinii was the highestamong the species studied. Lindholm andVasander (1990) showed the same trendfor S. fuscum. The next highest productiv-ity values were observed in S. lindbergiiand S. pacificum. The high vertical growthof both species contributed considerablyto this productivity, as they had the lowestbulk density among the species studied.The productivity of S. rubellum was closeto that of S. pacificum, but this dependedmore on bulk density than on verticalgrowth. The vertical growth and bulk den-sity of S. papillosum were relatively low,resulting in low overall productivity.Although S. tenellum had the highestnumber of capitula, or compact heads ofindividual Sphagnum plants, this specieshad the lowest productivity per areaamong the species studied because of itslow bulk density (Table 4.1). The annualstem growth of P. schreberi was about 22 mm/yr compared to about 9 mm/yr for R. lanuginosum (Table 4.1); however, theannual production of R. lanuginosum washigher than that of P. schreberi because of

62

100

90

80

70

60

50

40

30

20

10

0

Clim

atic

inde

xPr

ecip

itatio

n (m

m/d

)G

row

th r

ate

(mm

/d)

16

14

12

10

8

6

4

2

0

0.25

0.20

0.15

0.10

0.05

0.00

25

20

15

10

5

0

(a) Pleurozium schreberi (n = 30)

Tem

per

atur

e (°

C)

(b)

(c)

PrecipitationMaximum temperatureMinimum temperatureMean temperature

June

6–1

7

June

18–

July

1

July

2–1

5

July

16–

29

July

30–

Aug

ust

12

Aug

ust

13–2

6

Nov

embe

r 19

–Ju

ne 3

0

Aug

ust

27–

Nov

embe

r 18

. Growth patterns of Pleurozium schreberi in relation to climatic parametersfor eight consecutive sampling intervals from June 1999 to July 2000: (a) mean daily growth (±1 SE); (b) mean daily precipitation, and dailymaximum, minimum, and mean temperatures; (c) mean daily climatic index(when temperature = daily mean, and temperature threshold, x = 7)(adapted from Asada et al., 2003a, see reference for the mathematicalformula for climatic index).

63

200

150

100

50

0

Clim

atic

inde

x

(f)

18

16

14

12

10

8

6

4

2

0

Prec

ipita

tion

(mm

/d)

22201816141210 8 6 4

2

Tem

per

atur

e °C

PrecipitationMaximum temperatureMinimum temperatureMean temperature

(e)

1.00.80.60.40.20.0

Gro

wth

rat

e (m

m/d

)

0.20.0

0.80.60.40.20.0

(d) S. lindbergii (n = 20)

(c) S. pacificum (n = 20)

(b) S. fuscum (n = 32)

0.20.0

(a) S. austinii (n = 20)

May

21–

June

6

June

7–1

7

June

18–

July

1

July

2–1

5

July

16–

29

July

30–

Aug

ust

12

Aug

ust

13–2

6

Aug

ust

27–

Nov

embe

r 18

. Growth patterns of four Sphagnum species in relation to climatic parametersfor eight consecutive sampling intervals, May–November 1999: (a)–(d): meandaily growth (±1 SE) of sphagnum; (e) mean daily precipitation, and dailymaximum, minimum, and mean temperatures; (f) mean daily climatic index(when temperature = daily mean, and temperature threshold x = 0) (adapted from Asada et al., 2003a, see reference for the mathematicalformula for climatic index).

64

its denser growth form. Based on thecomparison of measurements of the mostwidely measured species, Sphagnum fus-cum, the productivity of sphagnum moss-es tended towards the top of the range ofsimilar measurements made in othersphagnum-dominated peatlands inCanada (Asada 2002).

When the maximum growth rates ofthree common sphagnum species at thePort Simpson and Diana Lake sites werecompared, S. rubiginosum showed consid-erably higher growth rates in the cutoverarea (85 mm/yr vs. 55 mm/yr) than in thenatural area; the other two species hadsimilar growth rates at both areas. Thisindicates that the conditions in themounded cutblock may enhance thegrowth rate of S. rubiginosum.

The area and volume covered by moss-es, especially sphagnum, expanded con-siderably in 1 year, particularly at the twowetter locations (Figure 4.6), while at thedriest location the changes were not near-ly as great. This shows that moisture isimportant in moss colonization and thatmosses are actively colonizing more area.

Total ecosystem productivity amongthe five open peatland communities washighest on the Sphagnum austinii hum-mocks and lowest in the Rhynchosporaalba – Sphagnum tenellum lawns (Table4.4). Moss growth provided the greatestamount of productivity to all communi-ties except the Menyanthes trifoliata pool.The total net primary productivity ()for the bog was not high because the bogwas dominated by the low productivityRhynchospora alba – Sphagnum tenellumlawns. Peatlands with a different plantcommunity composition (e.g., one domi-nated by Sphagnum austinii hummocks)would likely have a much higher .

The rate of mass loss was not statisti-cally different among the communities atthe Port Simpson site, ranging from 15.7to 17.7% (Table 4.5). The mass loss rates atthe Port Simpson site were not signifi-cantly different from any communities atthe Diana Lake site. At the Diana

site, decomposition was fastest in theSphagnum austinii hummocks and Carexutriculata – Sphagnum lindbergii depres-sions and slowest in Menyanthes trifoliatapools in the open peatland (Asada et al.2004). Most of the mass loss occurred inthe first year, a result which is in agree-ment with other studies. When mass losswas examined in relation to the watertable, decomposition was significantly

0 20 cm

1998

Bare groundSphagnum girgensohnii

1999

. Change in cover of Sphagnumgirgensohnii between 1998 and1999 at one of the three PortSimpson sites (adapted from Asadaet al., 2004).

65

. Estimated total net primary production (NPP; g/m2 per year)a for the five representative micro-communities in the openbog at the Diana Lake study site (adapted from Asada, 2002)

Above ground Below ground NPPb Total NPP Range ofNPP Minimum Maximum Minimum Maximum A/B ratioc

Menyanthes trifoliata pool 104.7 ± 23.5a 85.5 ± 18.6a 164.6 ± 40.0ab 190.2 ± 41.5ab 269.3 ± 62.8ab 1.2–0.6

Carex utriculata – Sphagnum 300.9 ± 32.4b 121.5 ± 38.8a 194.6 ± 41.5ab 422.5 ± 63.8ac 495.6 ± 51.8c 2.5–1.5lindbergii depression

Rhynchospora alba – Sphagnum 163.6 ± 23.6a 15.1 ± 2.9b 71.6 ± 13.9a 178.7 ± 25.2b 235.2 ± 32.9b 10.8–2.3tenellum lawn

Racomitrium lanuginosum 291.3 ± 30.5b 43.9 ± 5.0a 164.7 ± 19.2b 335.2 ± 30.4ac 456.1 ± 35.4ac 6.6–1.8hummock

Sphagnum austinii 402.4 ± 14.5b 24.1 ± 9.1ab 91.8 ± 34.6ab 426.5 ± 23.5c 494.2 ± 48.9ac 16.7–4.4hummock

a Values are means ± standard error. Means followed by a different letter are significantly different (p < 0.05).b A fixed ratio of (below ground ) / (Total ) = 0.5 was applied to estimate below ground for Menyanthes trifoliata and 0.88

for Carex utriculata. For other vascular plants, the estimated below ground includes only fine roots, with some range was consid-ered. For the Menyanthes trifoliata pool, the Carex utriculata – Sphagnum lindbergii depression and the Rhynchospora alba – Sphagnumtenellum lawn, the ratio of 0.33 was used for the lowest estimation, and 0.70 for the highest estimation. For the Racomitrium lanugi-nosum hummock and the Sphagnum austinii hummock, the ratio of 0.38 was used for the lowest estimation, and 0.70 for the highestestimation.

c Ratio of above- and below-ground NPP.

. Mass loss (decomposition) of Sphagnum fuscum litter from litter bags incubated at 10 cmbelow ground surface for 1 year (adapted from Asada et al., 2004)

Study site Site seriesa Communityb Mass loss(%)c

Port Simpson –d P1 17.4 ± 2.3ab (6)– P2 16.0 ± 1.1ab (20)– P3 17.7 ± 0.6ab (14)– P4 15.7 ± 1.2ab (6)

Diana Lake 04 D1 16.5 ± 1.1ab (6)01 D2 12.9 ± 1.3b (10)11 D3 16.2 ± 1.2ab (9)12 D4 16.5 ± 1.3ab (13)32 D5 23.7 ± 0.9a (3)32 D6 14.4 ± 1.5b (12)32 D7 17.1 ± 0.6ab (6)32 D8 21.0 ± 0.3ab (4)32 D9 13.5 ± 0.4ab (2)

a Site series 32: Non-forested slope – blanket bog; site series; 12: Shore pine – yellow cedar – Sphagnum; siteseries; 11: Western redcedar – yellow cedar – Goldthread; site series; 01: Western redcedar – Western hem-lock – Salal; and site series 04: Western hemlock – Sitka spruce – Lanky moss.

b P1 = Sphagnum angustifolium community; P2 = Polytrichum formosum – Sphagnum girgensohnii communi-ty; P3 = Cornus canadensis – Hylocomium splendens community; P4 = Sphagnum pacificum community.D1–D5 are micro-communities in the non-forested slope–blanket bog site series and D6–D9 are communi-ties at site series level. D1 = Menyanthes trifoliata pool; D2 = Carex utriculata–Sphagnum lindbergii depres-sion; D3 = Rhynchospora alba – Sphagnum tenellum lawn; D4 = Racomitrium lanuginosum hummock; andD5 = Sphagnum austinii hummock.

c Values are means ± standard error; number of plots appears in parenthesis. Means followed by a differentletter are significantly different (p < 0.05).

d Mainly dominated by 01 before clearcutting and mounding.

66

greater in the aerobic zone above thewater table than in the anaerobic zonebelow the water table, with intermediatedecomposition rates in the zone of watertable fluctuation (Asada and Warner2005). The rate of mass loss was slightlyhigher in this study than in comparablestudies in other areas.

The long-term peat accumulation rateon the peatland is likely lower than incontinental peatlands. From a series of C14-dated peat cores, Turunen andTurunen (2003) found that the averagevertical peat accumulation rate (over thepast ± 8000 years) at Diana Lake was 0.15 mm/yr, with a range of 0.09–0.24mm/yr. This accumulation rate is lowerthan that found in other studies in conti-nental North America, which ranged from 0.39 to 1.05 mm/yr, as well as south-east Alaska, which ranged from 0.18 to1.05 mm/yr (Gorham et al. 2003).

Recent peat accumulation rates at theDiana Lake bogs, measured using 210Pbtechniques, are 1.4–3.2 mm/yr over thepast 65–70 years and 0.9–1.9 mm/yr overthe past 200 years, indicating that carbonhas accumulated under normal climate

conditions in the recent past (Turunenand Turunen 2003; Asada and Warner2005).

Researchers concluded from the studiesat Diana Lake that hypermaritime peat-lands rank lower than other continentalpeatlands in overall and carbon accu-mulation. Although some hypermaritimepeatland microcommunities (e.g., S. fus-cum and S. austinii hummocks) have rela-tively high and peat accumulationrates, others (e.g., Rhynchospora alba – S. tenellum lawns) are low in productivity.Relatively high decomposition rates inhypermaritime peatlands tend to offsetproduction, even in the most productivesphagnum communities, thus yielding rel-atively low overall rates of peat and car-bon accumulation (Malmer and Wallen1993; Asada and Warner 2005). Near sur-face peat carbon balance studies indicatethat both the S. austinii and R. alba – S.tenellum communities are carbon sinks,although the carbon balance in the less-productive R. alba – S. tenellum commu-nities could be close to equilibrium(Asada and Warner 2005).

The vegetation of the Diana Lake area ischaracteristic of that on the north coast;similar plant communities are describedwithin the Biogeoclimatic EcosystemClassification () system (Banner et al.1993). The driving environmental factor indetermining these communities is mois-ture. This is exemplified in the study areaby the importance of drainage and watertable depth. For example, the moundingtreatment at the Port Simpson site alteredthe moisture regime in the mounded areathrough the formation of pits adjacent to most mounds. These pits (many hadstanding water) were subsequently invad-ed by sphagnum mosses that were notpresent or less common in the area beforeharvesting occurred. These mosses are stillexpanding in extent and may have the

potential to paludify portions of adjacentupland sites.

The sphagnum moss species examinedhad different growth responses to climaticvariation, mostly related to their habitatand growth form. Species that form hum-mocks had lower linear growth rates andless seasonal variation in growth, thanspecies that grew in wetter conditions,such as lawns and hollows. Differences inmoisture regime between hummocks andhollows may explain these differences.Because hollows are wet most of the year,species in this habitat type can use watermore easily and therefore undergo lessstress than hummock-forming species.During dry periods when the water leveldrops, however, species in hollows cannotretain water for growth because of their

4.4 VegetationTypes and their

Dynamics:Discussion

67

loose growth form. Conversely, hum-mock-forming species, with their densergrowth form, can retain water even in dryperiods because of their superior water-holding capacity. The moisture content inhummocks, therefore, is lower but moreconstant than that in hollows. This allowshummock-forming species to grow duringdry periods as well as during wetter peri-ods, although the growth rate would beslow. These differences in growth patternbetween hummock-forming and hollowor lawn-forming species agree with someprevious findings (Moore 1989; Gerdol1995).

Even if adequate moisture is present,substantial growth will not occur if thetemperature is too low. This hypothesiswas supported by higher correlationsbetween growth and the climatic indexthan precipitation alone for most of thespecies studied (Table 4.1). Previous stud-ies have observed this relationship foronly a few species. For example, Lindholm(1990) determined that the minimumtemperature for growth of Sphagnum fuscum was 0°C; above this temperature,growth was controlled by water availabili-ty. Gerdol (1996) observed the same trendfor S. magellanicum. Vitt (1989) confir-med the importance of precipitationabove temperature thresholds with thefinding that yearly growth variation ofRacomitrium microcarpon was related toprecipitation during the growing season.

Sphagnum species and the other twomoss species exhibit different temperaturethresholds for growth. Our preliminaryresults on the relationship between mossgrowth and the climatic index indicatethat the temperature threshold for sphag-num growth is about 0°C; for R. lanugi-nosum and P. schreberi, it is about 5°C.These low thresholds suggest potentialwinter growth, especially for sphagnum,in this mild hypermaritime region. Wintergrowth appears considerable, as is evidentfor sphagnum in other hyperoceanicregions (Hulme and Blyth 1982).

Over the 8 years following forest

harvesting at Port Simpson, sphagnummoss growth has progressed as follows:• Clearcutting alone has not yet promot-

ed significant colonization or advance-ment of sphagnum.

• Mounding after clearcutting created hol-lows in which pools formed or wherethe water table was very shallow.

• The exposed peat provided a competi-tion-free substrate for pioneer sphag-num moss species to invade.

• The water chemistry gradient set up bysphagnum along the mound–hollowtransition may further facilitate sphag-num moss growth and discourage thegrowth of other plant species.

Paludification at this site is evident by:• The presence of S. pacificum and S.

angustifolium, which were presumablyalmost absent before harvesting. Thesespecies are increasing in area and vol-ume, especially in the hollows. They arethought of as pioneer species, whichlater provide conditions appropriate forthe establishment of other sphagnumspecies.

• The rapid expansion of S. girgensohniipatches that presumably help to createlawns on which other bog sphagnumspecies (e.g., S. capillifolium) can es-tablish.

• The vertical growth rate of sphagnumat the Port Simpson site is about thesame or faster than that at the DianaLake site.

• The decomposition rates at the PortSimpson site are similar to, or slightlyslower than, those at the Diana Lakesite.We are not clear how paludification

will proceed at the Port Simpson site inrelation to forest regeneration; we willcontinue site monitoring indefinitely.Three developmental pathways are possi-ble for these sites:1. Tree regeneration doesn’t proceed well,

sphagnum continues to expand, andspecies composition changes throughsuccession with expansion of fen orbog communities in the cutover area.

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4.5 Soil Ecology

2. Tree regeneration proceeds moderatelywell on the mounds; because of shad-ing the expansion of bog-type sphag-num stops and shade-tolerantforest-type sphagnum becomes domi-nant. The area becomes a wet lower-productivity forest (similar topre-harvest condition).

3. Regeneration proceeds well on themounds and, because of increasinginterception and evapotranspiration,the water table drops. Sphagnumspecies are unable to persist or expand,and an upland forest results with high-er tree productivity than the pre-harvest stand.

4.5.1 Soil/bedrock relationships Mineralsoils on the north coast are typically collu-vial or saprolitic in origin, most oftendeveloping in shallow veneers overbedrock. The most common bedrocktypes on the north and central coast are:• granodiorite (including quartz diorite

and diorite),• gneissic diorite, and• schist or gneiss, with some localized

areas of limestone (Figure 4.7).These bedrock types have differences in

weathering rates and mineral composition(Table 4.6) resulting in a range of physicaland chemical soil properties. Granodioriteis an igneous intrusive rock with a highcontent of quartz, feldspar, and some

biotite. It is a relatively hard rock thatweathers slowly, and the mineral soilsderived from it are generally shallow and nutrient poor. Gneissic diorite is anigneous intrusive rock with less quartzand more biotite, garnet, and some horn-blende. Gneissic diorite is slightly banded,or foliated, suggesting that partial meta-morphism has taken place. In this case,the layering results from additional pres-sure, temperature, or chemical reactionsapplied to the rock. Gneissic diorite isscattered throughout the CWHvh2(Figure 2.1) and data suggest that this rocktype is associated with slightly more pro-ductive sites compared with the granodi-orites. Schist is a strongly foliated, or

. Four common bedrock types found on the north and central coast of British Columbia.

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layered, metamorphic rock, intermediatebetween slate and gneiss with a high con-tent of mica or mica-like minerals. Thisrock type is relatively soft and weathersquickly to create mineral soil and providenutrients for plant growth. As a result,some of the highest forest productivity onthe outer coast is associated with schistbedrock, especially when it occurs in com-bination with limestone. Limestone islargely made up of calcium carbonate; inthe CWHvh2, it is limited to small pocketsscattered along the coast. Limestoneweathers by solution and gives rise to generally rich, productive forests (e.g.,CWHvh2/05, Western redcedar – Sitkaspruce – Swordfern), and often uniqueplant communities (Kranabetter andBanner 2000).

We examined the relationship betweenbedrock type and mineral and organic soildepth using information from the PrinceRupert Forest Region ecological database,which includes 165 ecosystem plots collected from sites throughout theCWHvh2. These plots were collected overthe last 25 years to develop an ecosystemclassification, and thus were not specific-ally designed to determine relationshipsbetween bedrock and soil. Soil horizonthicknesses were combined for both theorganic and mineral layers to arrive at thetotal depth for each of these soil layers.The depth of mineral soil must be inter-preted carefully, however, because innearly one-half of the plots bedrock was

not reached in the soil pit; in these cases,the measured mineral soil depth will par-tially depend on the thickness of the over-lying organic layer.

Tables 4.7 and 4.8 summarize soildepth related to site series and bedrocktype. Table 4.7 illustrates the trends inmineral and organic soil depth among siteseries; organic horizon depth tends toincrease and mineral soil depth tends to decrease from the productive uplandforests (CWHvh2/04) to the bog forests(CWHvh2/11). These trends were generallynot statistically significant (p < 0.05),except for the thinner organic horizondepth on the CWHvh2/04 sites seriescompared with the CWHvh2/01 and /11.Within both the CWHvh2/01 and /04 siteseries, a trend exists in mineral soil depthas it relates to bedrock geology, with thedeepest mineral soils occurring on themetamorphic (schist) bedrock (Table 4.8).Again, the data are highly variable andthis trend was not statistically significant.A trend in organic soil depth withbedrock type within site series was lessapparent, indicating slightly shallowerorganic horizons on metamorphic rockwithin the CWHvh2/04 site series only.

The nutrient differences between soilsderived from the various rock types arelargely due to varying amounts of phos-phorus (P), sulphur (S), magnesium (Mg),and potassium (K) (Table 4.9) (Kranabetterand Banner 2000). For example, schist-derived mineral soils are higher in P, S,

. Total chemical concentrations for bedrock typesa (adapted from Kranabetter and Banner, 2000)

P S Ca Mg K Mo Cu Fe Mn Zn CoBedrock type (g/kg) (g/kg) (g/kg) (g/kg) (g/kg) (mg/kg) (mg/kg) (g/kg) (g/kg) (mg/kg) (mg/kg)

Granodiorite 1.07 0.33 29.5 14.8 33.8 < 2 4.8 37.1 0.7 50.2 5.3(0.3) (0.2) (4.4) (3.7) (11.8) (0.75) (7.5) (0.1) (5.3) (1.39)

Gneissic diorite 2.12 2.51 48.8 24.6 23.8 < 2 30.8 63.0 1.1 100.5 10.2(0.2) (2.4) (6.8) (7.1) (6.9) (23.5) (13.6) (0.2) (37.9) (2.95)

Schist 2.15 0.45 87.6 33.9 11.8 3.7 18.3 84.2 1.0 42.0 9.7(0.2) (0.2) (40.1) (7.2) (2.3) (2.5) (7.3) (26.1) (0.4) (10.0) (4.16)

Limestone 0.20 2.83 520.6 9.4 0.4 < 2 < 1 2.6 0.2 8.7 < 1(0.1) (0.1) (15) (3.8) (0.2) (1.3) (0.1) (2.6)

a Values in parentheses are standard errors.

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Mg, and K than mineral soils derivedfrom other bedrock types. These nutrientson their own can influence site productiv-ity, but they can also lead to higher nitro-gen (N) availability (measured asmineralizable N), a nutrient fundamentalto plant growth. At the other end of thespectrum, soils derived from granodioriteare low in nutrient elements, while soilsfrom gneissic diorite tend to be interme-diate between schist and granodiorite.

The scarcity of glacial till on the north

coast has significant implications for for-est productivity. Glacial till is typicallycomposed of a mixture of ground uprocks of varied mineralogy. It has highsurface area, and good potential for rootaccess, balanced nutrient content, andweatherability. Soils derived from bedrockthat has weathered in situ, such as thoseon the north coast, are generally less bal-anced in their nutrient content and limit-ed by the specific chemical and physicalproperties of the rock.

. Mean organic and mineral soil depths for CWHvh2 site series on the north and centralcoastal of British Columbia

Site series n Organic soil depth (cm)a n Mineral soil depth (cm)a

11 29 37.0a (3.5) 24 22.5a (4.6)01 60 31.7a (2.5) 57 30.9a (3.0)04 76 20.4b (2.2) 76 36.8a (2.6)

a Values in parentheses are standard errors. Means followed by a different letter are significantly different (p < 0.05).

. Mean organic and mineral soil depths for CWHvh2/01 and CWHvh2/04 site series bybedrock type on the north and central coast of British Columbia

Site series Bedrock type n Organic soil depth (cm)a n Mineral soil depth (cm)a

01 Granitic 37 34.3 (3.7) 34 24.9 (3.7)Gneissic diorite 15 23.1 (5.9) 15 41.4 (5.6)Schist 7 35.1 (8.6) 7 37.6 (8.2)

04 Granitic 35 21.4 (2.3) 35 37.2 (4.1)Gneissic diorite 25 19.7 (2.8) 25 32.0 (4.9)Schist 14 17.9 (3.7) 14 45.4 (6.5)

a Values in parentheses are standard errors. Means within a site series were not significantly different (p < 0.05).

. Average chemical properties of mineral soils (0–20 cm), well-drained sites only a (adapted from Kranabetter and Banner,2000)

Bedrock-derived Total N Total P Total S C:N C:P C:S Min.-N Avail. P Exch. Ca Exch. K Exch. Mg pHsoil (g/kg) (g/kg) (g/kg) ratio ratio ratio (mg/kg) (mg/kg) (cmol/kg) (cmol/kg) (cmol/kg) (H2O)

Granodiorite 1.8 0.23 0.22 29.1 220a 284a 14.6a 5.49 0.67 0.049a 0.19a 4.47 (0.3) (0.21) (0.05) (1.1) (14.9) (21.4) (1.6) (0.7) (0.06) (0.006) (0.02) (0.03)

Gneissic diorite 2.4 0.35 0.34 26.6 169ab 195ab 18.9a 8.78 0.70 0.050a 0.22a 4.49 (0.8) (0.83) (0.18) (1.5) (13.6) (11.7) (3.0) (2.6) (0.14) (0.008) (0.04) (0.05)

Schist 2.3 0.41 0.33 23.6 134b 170b 45.0b 8.79 1.64 0.109b 0.49b 4.64 (0.3) (0.47) (0.04) (1.0) (9.8) (12.0) (7.1) (1.6) (0.26) (0.010) (0.04) (0.10)

a n = 3 for each bedrock type. Values in parentheses are standard errors. Values followed by a different letter are significantly different (p < 0.05).

71

Where roots have access to rock sur-faces, recent studies have demonstratedthe capacity for root and mycorrhizaeexudates such as organic acids to weatherrocks and take up nutrients directly(Jongmans et al. 1997; Bormann et al.1998). Root and mycorrhizae access maybe extremely limited, however, on hardplutonic rocks because of the lack of frac-tures and low surface area. Where deep,wet organic horizons develop, they canalso prevent access to the underlyingweathered bedrock. On the more easilyweathered and fractured metamorphicrock, root access is much better, but com-pared with glacial till, even this relativelynutrient-rich bedrock is less balanced andmore subject to single nutrient deficien-cies. These rocks have already undergonesignificant weathering, which has removedmany of the most weatherable minerals.

The implications to forest managementof this lack of glacial till on the northcoast are significant, especially because it is the harder, resistant, and relativelynutrient-poor plutonic rocks that domi-nate the coast. Low rates of nutrientinputs to these systems via slow weather-ing and atmospheric deposition (rain,clouds, fog) mean that longer rotationswill be required to re-establish mer-chantable forests in these areas, and fertil-ization treatments may also be necessary.Initial results from the HyP3 studies sug-gest that the inherent forest productivity,as well as the potential to improve pro-ductivity through site treatments, is con-siderably higher in the areas dominated by metamorphic bedrock.

4.5.2 Soil disturbance and nutrient avail-ability Though bedrock plays asignificant part in determining nutrientavailability and site productivity, distur-bance history also plays a role. On thenorth coast, high forest productivity isgenerally associated with sites on steepslopes with good soil drainage and aera-tion, and often a history of natural distur-bance by landslide or windthrow events.

These disturbance events tend to mixmineral and organic soil layers, slowingthe buildup of surface organic material,and improving nutrient availability(Bormann et al. 1995). In contrast, thelower-productivity western redcedar-dominated sites (CWHvh2/01 and /11)found on the gentle terrain of the HecateLowlands are imperfectly to poorlydrained, and have much lower levels ofavailable nutrients (Kranabetter et al.2003). These sites lack disturbances, whichallows deep layers of organic matter toaccumulate. If disturbance events are rareor small, deep accumulations of surfaceorganic matter result. On these sites, thedepth of the organic layers prevents treeroots from gaining access to mineral soil. In some cases, mineral horizons areabsent (Folisols) and forest floors play anincreasingly important role in nutrientsupply (Chapter 2, section 2.3).

4.5.3 Organic matter and nutrient avail-ability Edmonds et al. (1989) suggestedthat nutrient availability from forest floorsdepends on the turnover rate and nutrientcontent of the organic matter. These fac-tors are examined in two HyP3 soil stud-ies. Kranabetter and Banner (2000)compared chemical properties and labmicrobial respiration rates (as an indica-tor of decomposition rates) in forest floorsamples collected from productive, freelydrained forest sites occurring on contrast-ing bedrock types (granodiorite, gneissicdiorite, schist, and limestone).Kranabetter (B.C. Ministry of Forests2004, unpublished data) compared thesame forest floor properties amongCWHvh2/01, /04, and /11 site series, andthen manipulated water content of forestfloor samples to see whether moisturecontent influenced decomposition rates(measured as microbial respiration in thelab).

Although organic matter turnover rateswere expected to be higher on the richerbedrock types, on the more productivesite series, and in the least-saturated forest

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floors, this was not apparent in the labrespiration results. Microbial respirationwas variable in the incubated forest floorsamples taken from the top 15 cm of soilprofiles, but broadly similar on freelydrained sites across contrasting bedrocktypes (Figure 4.8a). Across site serieseither at field moisture content, or athigher or lower moisture levels, no statis-tically significant trends were evident(Figure 4.9). Surprisingly, some samplesrepresenting the wettest forest floors fromthe poorest site series had the highest res-piration rates.

Lower C:N and C:P ratios on the richerschist-derived soils (Figure 4.8b), and onthe most productive site series in bothold-growth and second-growth conditions(Figure 4.10), suggest that organic matterquality is better characterized by nutrientcontent than by turnover rates. Theresults imply that the decline in tree pro-ductivity across site series more stronglyreflects a decline in the available nutrient

content of partially decomposed organicmatter (the end product of decomposi-tion) than lower decomposition rates.

These laboratory respiration experi-ments do not completely mimic fieldprocesses, however. The CWHvh2/01 and/11 site series could experience periods ofcomplete saturation and reduced decom-position compared to well-drained sites,especially at depths deeper than 15 cm, asmeasured in this study. The tests conduct-ed in this experiment were limited to car-bon cycling (CO2 release). It is possiblethat the wetter soil conditions could leadto differences in faunal and microbialactivity that affect N rather than C miner-alization and this may result in differencesin organic matter “quality.” The P contentof litter and soil has been reported to control N mineralization in upland andorganic soils (Purchase 1974; Munevar andWollum 1977; Pastor et al. 1984; Whiteand Reddy 2000; Carlyle and Nambiar2001), and is generally recognized as

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exerting a large influence on N cyclingand fixation (Chapin et al. 1978; Cole andHeil 1981; Vitousek and Howarth 1991).Low supplies of P, due to lower-qualityparent materials or reduced rooting inmineral soils beneath deep surface organiclayers, may limit N availability and thismay in turn result in a decline in forestproductivity. Ecosystem decline resultingfrom the long-term absence of catastroph-ic disturbance has been linked to P limita-tions in a recent study of contrastingchronosequences in tropical, temperate,and boreal zones (Wardle et al. 2004).

Early results from operational trialssuggest that long-term improvements intree productivity require mixing of organ-ic matter with mineral soil horizons toimprove soil aeration and to increase theuptake and cycling of P, N and S. Thistreatment is thought to mimic thebeneficial consequences of natural distur-bances, such as colluvial mixing or blow-down events, which are associated withsites that support more productive standsin these coastal forests (Kranabetter andBanner 2000).

Mixing and mounding site treatmentsare being tested at operational trials at thePort Simpson and Oona River study areas(Chapter 6, sections 6.2 and 6.3).

4.5.4 Tree growth and foliar nutritionTree growth and nutrition in second-growth plantations (approximately 20 years of age) were compared across arange of sites (e.g., CWHvh2/ 01, /04, /05,/06, /07, and /11 site series) occurring overvarious bedrock types from granodioriteto schist (Kranabetter et al. 2003). Foliaranalysis was used to infer which nutrientelements were at adequate levels andwhich limited growth (van den Driessche1974; Ballard and Carter 1986; Walker andGessel 1991). To examine relationshipsbetween foliar nutrition and growth, foliaranalysis was carried out on sample treesfrom which height and increment meas-urements were taken. To assess plantresponse to nutrient limitations, nutrient

retranslocation between current andolder foliage was also examined. This use-ful method is based on the theory thattrees on nutrient-poor sites will retranslo-cate, or move, nutrients from older foliage to younger foliage to compensate fordeficiencies in available soil nutrients(Nambiar and Fife 1991).

Foliar chemistry, rather than soil chem-istry, was used to ascertain nutrient avail-ability on these sites because studies showthat soil chemistry is of limited value indetermining nutrient availability. Soilanalysis measures the supply of elementspotentially available, whereas foliar analy-sis provides an index of the amount actu-ally taken up by the trees (Ballard andCarter 1986). In addition, soil analysis isoften difficult to interpret when forest soildepth and composition are extremelyvariable, as is often the case on the outercoast of British Columbia.

Many foliar nutrient concentrations(e.g., N, P, K, S) had a positive relation-ship with leader increment. As leaderincrement continued to increase, thesenutrients did not appear to “plateau” atthe adequate concentrations previouslydetermined in greenhouse growth tests byBallard and Carter (1986) (Figures 4.11,4.12, and 4.13). Some foliar cation concen-trations (e.g., Ca, Mg) showed little rela-tionship to growth. Trees on the bettergrowing sites (well-drained schist soilsand seepage sites; CWHvh2/04, /05, /06,and /07 site series) in this study exhibitthe highest productivity that has beenfound in the hypermaritime zone. Typicalfoliar nutrient concentrations for eachtree species from these more productivesites (Table 4.10) were compared withpublished reports of adequate foliar nutri-ents. Western hemlock and Sitka sprucehad nearly adequate concentrations of N(1.45–2.2%) and P (0.25–0.35%) on pro-ductive sites (Radwan and Harrington1986; Weetman et al. 1989a, 1989b; Walkerand Gessel 1991). In general, the cationsand micronutrients on productive siteswere also at adequate concentrations, as

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. Western hemlock nutrient concentrations for current-year needles and 1-year-old needles across height increment(adapted from Kranabetter et al., 2003).

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reported by Ballard and Carter (1986). Thelargest discrepancy between observed andadequate nutrient levels occurred with Pin western redcedar (0.28% P comparedto the suggested level of 0.16%). Accordingto published standards, levels as high as0.28% P occur more often in interior red-cedar (Radwan and Harrington 1986).Such a large variation from the expected Pconcentration implies that the suggestedlevel of 0.16% may underestimate the trueP requirements for western redcedar onthese sites.

All three tree species had strong posi-tive correlations between average leaderincrement and foliar N, P, and S, alongwith secondary correlations for manycations or micronutrients. The generallypositive, linear response of many foliarmacro- and micronutrients made itdifficult to infer specific growth limita-tions. It is unclear, for example, whetherthe availability of N, P, S, K, Mg, Cu, Fe,Mn, and Zn in soils changed across mois-ture and bedrock regimes, or whether thedeficiencies of N or P simply limited theuptake of these other elements. The strongcorrelations between micronutrients suchas Fe and Zn and leader increment wereoften species specific, an aspect that wouldbe interesting to test further in field trials.

Retranslocation between new and olderfoliage was determined by comparingnutrient concentrations of current needlesagainst the previous year. The largest dif-ference in foliar nutrient concentrationsgenerally occurred in more productivetrees; nutrient concentrations on the moststressed sites showed generally more sta-bility between years (Figures 4.11, 4.12, and

4.13). The slightly higher rate of S accu-mulation for western hemlock was theonly difference in nutrient concentrationsbetween new and older foliage that sug-gested a larger deficiency on poorer sites.On richer sites (CWHvh2/05 and /07 sitesseries), where N availability might be nat-urally quite high, the large decrease in Sand Mg concentrations in older needlessuggested Sitka spruce was limited bythese elements. This is similar to theinduced deficiencies that can sometimesoccur when N fertilizer is applied(Brockley et al. 1992). Western hemlockalso showed similar patterns of possibleMg retranslocation on seepage sites.Overall, the observed patterns of retrans-location are opposite from the patternoriginally expected. Rather than findinggreater retranslocation on nutrient-poorsites as a response to stress, greater move-ment of nutrients between old and newfoliage was recorded on richer sites. Thesepreliminary findings raise new questionsconcerning nutrient limitations to growth,especially on richer sites; further field testswith added nutrients would be needed todraw more complete conclusions.

Although vegetation competition oredaphic conditions posed no apparentdifficulties in establishing trees on theCWHvh2/01 sites studied, the heightincrement results show considerable dif-ferences in growth rates from well-drainedto imperfectly drained sites. Incrementgrowth on the CWHvh2/01 sites averaged42% less for western hemlock, 56% lessfor Sitka spruce, and 32% less for westernredcedar compared with the better-drained sites. Bedrock also had an

. Foliar nutrient concentrations for western hemlock, Sitka spruce, and western redcedar on productive sites of northcoast British Columbia (adapted from Kranabetter et al., 2003)

N P S Mg K Ca B Cu Fe Mo Mn Zn

Species (%) (ppm)

Western hemlock 1.45 0.28 0.12 0.120 0.90 0.25 15 3.0 35 0.02 1500 12Sitka spruce 1.55 0.22 0.11 0.085 0.90 0.40 10 3.0 30 0.02 1000 25Western redcedar 1.85 0.28 0.11 0.150 0.90 0.65 15 5.0 30 0.20 250 20

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influence on growth increment. TheCWHvh2/01 sites on granodiorite andgneissic diorite bedrock showed the lowestgrowth rates (Table 4.11), suggesting thatthese sites are at the lowest threshold ofoperability. The CWHvh2/01 schist sites,however, had more acceptable rates of treegrowth, and are thus considered to havehigher potential for forestry operations.

The height increment results for west-ern redcedar, Sitka spruce, and westernhemlock illustrate some important aspectsof the autecology of these species. Westernredcedar, although relatively slow grow-ing, had the smallest decrease in heightincrement across the site series, and thusseems better adapted to the poorer soilsover the long term. Considering ecologicalsuitability as well as species value, westernredcedar should be chosen as the preferredspecies on most CWHvh2/01 sites. Sitkaspruce exhibited by far the best growth onthe good sites, but showed dramaticallyreduced growth on the poor sites, espe-cially on granodiorite. Species selectionguidelines reflect the higher nutrient andsoil drainage demands of this species(Banner et al. 1993), and thus spruce is theleast acceptable tree species on CWHvh2/01

sites. The autecological characteristics ofwestern hemlock are intermediate betweenthose of western redcedar and Sitkaspruce. This species, therefore, could beconsidered an acceptable or preferredspecies on CWHvh2/01 sites, dependingon specific management objectives andother factors (e.g., mistletoe risk). SeeChapter 5 (section 5.3 and Table 5.1) for asummary of tree species productivity inthe CWHvh2, and Chapter 7 for a furtherdiscussion of species selection guidelines.

The growth and foliar responsesobserved largely confirm the lower pro-ductivity of the CWHvh2/01 site series,especially on poorer bedrock types, andprovided further evidence that N and Pavailability declines along the productivitygradient. Operational trials are under wayat Port Simpson and Oona River to testwhether the availability of N and othernutrients is enhanced by mixing mineralsoil with forest floors, which simulatesblowdown events, or through additions ofP fertilizer (see Chapter 6). The growthand nutrition results from these currentstudies should allow us to better evaluatethe potential, and investment required, toimprove site productivity on CWHvh2/01

. Average height increment (cm) for each tree species by soil moistureregime and bedrock typea (adapted from Kranabetter et al., 2003)

Bedrock type

Site series Granodiorite Gneissic Schist

Western hemlock01 CwHwb Salal 14.0 (1.6) 5.6 (0.9) 38.0 (5.2)04–06 Site Seriesc 26.6 (4.6) 15.5 (1.8) 57.4 (3.8)07 CwSsb-Devil’s club 37.1 (5.4) 17.6 (1.9) 58.4 (5.6)

Sitka spruce01 CwHw Salal 5.8 (1.0) 9.1 (1.4) 21.7 (2.2)04–06 Site Series 14.0 (2.0) 21.3 (2.6) 49.1 (2.0)07 CwSs-Devil’s club 52.4 (5.0) 26.8 (3.6) 51.4 (4.1)

Western redcedar01 CwHw Salal 15.0 (1.8) 13.2 (1.2) 23.6 (1.5)04–06 Site Series 21.4 (1.8) 26.1 (2.3) 28.5 (2.0)07 CwSs-Devil’s club 26.3 (2.7) 25.8 (2.4) 31.1 (1.5)

a n = 3 per combination. Values in parentheses are standard errors.b Cw = western redcedar, Hw = western hemlock, Ss = Sitka spruce.c See Figure 2.7 for site series names.

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sites. Although the lowest-productivitysites on poorer bedrock may initially seemto have a greater need for productivity-improving site treatments, fertilization(rather than soil mixing) may be the onlyoption on these sites because very littlemineral soil is associated with the harderigneous rocks; the soils are most oftenFolisols, which consist of deep (forestfloor horizons) layers with a thin layer(less than 10 cm) of mineral soil over

rock. Metamorphic (schist) sites have thegreatest potential for improving nutrientavailability through soil-mixing treat-ments because mineral soils are oftenmuch deeper and higher in nutrientcation content. Although our existingoperational trials are both located onmetamorphic bedrock, we plan to estab-lish trials on poorer bedrock types to bet-ter define operability limits.

4.6 Model ofEcosystem

Development andProductivity in

the CWHvh2

From the studies of ecosystem patterns,processes, and productivity outlinedabove, a simple model of ecosystem devel-opment in the CWHvh2 has emerged(Figure 4.14). In this model, three mainfactors operate in combination to driveecosystem development and productivityin this hypermaritime environment:1. bedrock geology2. soil drainage3. disturbance history

Although these same factors influence

ecosystem development to some degree inmost other terrestrial environments, theirinfluence is especially dramatic in theCWHvh2. This model relates directly tothe edatopic grid typically used to portray site series (Figure 2.7); soil moistureand nutrient regime (and thus site series)are largely determined by the interactionof bedrock geology, soil drainage, and dis-turbance history.

The scarcity of glacial till in this coastalenvironment highlights the importance of

Bedr

ock

Drainage

Disturbance

BiomassBiomass

AllocationAllocation

Dynamic Stable

Igne

ous

Met

amor

phic Rapid

Poor

Trees vs. Mosses

MediumproductivityForests

ProductiveForests

Blanket Bogsand Bog Forests

Bedr

ock

Drainage

Disturbance

ForestForestProductivityProductivity

Dynamic Stable

Igne

ous

Met

amor

phic Rapid

Poor

LowMedium

High

. Simplified model of ecosystem development and forest productivity in the CWHvh2. Theversion on the left emphasizes the role of bedrock geology, soil drainage, and disturbancehistory in controlling tree productivity; the version on the right emphasizes how thesesame environmental factors determine the relative allocation of tree versus moss biomassin north-coast ecosystems.

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bedrock geology. Most soils developdirectly from the weathering of bedrockor colluvial material. This contrasts withmany other areas where a mantle of gla-cial till of mixed lithology masks theinfluence of bedrock. In addition, sharpcontrasts in bedrock type occur on theouter coast, from the hard, slowly weath-ering granodiorites with relatively lowamounts of available nutrient elements, tothe much softer, faster weathering meta-morphic rocks and limestone with morenutrient-rich lithologies. These differentbedrock types manifest themselves in dra-matic differences in plant communitiesand forest productivity.

Excess soil water is the rule in thishypermaritime environment, and subtlevariations in slope or internal soil drain-age result in significant differences in forest productivity. In contrast to themajority of other subzones in the province(where moisture deficits are common),the most freely drained sites in theCWHvh2 are the most productive sites fortrees. Even these “drier” sites are fresh tomoist in absolute terms, but as long as soilwater is dynamic rather than stagnant,then tree productivity will remain moder-ate to high.

The tendency for organic matter toaccumulate on sites that have not beendisturbed by windthrow, landslides, orfluvial disturbances for hundreds (orthousands) of years is also dramatic in theCWHvh2. As soil organic matter accumu-lates, soils become wetter and tree rootsbecome more confined to surface organichorizons. Although the nutrient capital in these organic horizons is considerable,

nutrient availability is relatively lowbecause of the wet, acidic conditions andlow rates of nitrogen mineralization.Better-drained sites that often have a his-tory of natural disturbance, especiallywhere soil organic and mineral horizonsare mixed, exhibit higher forest product-ivity.

Although models are inherently sim-plistic, on the majority of sites on theouter coast, ecosystem development andforest productivity can be explained bythe above three factors working in combi-nation. The model presented in Figure4.14 can also be used to guide forest man-agement investments and activities, and tohelp define and understand the limits ofoperability in the CWHvh2. For example,marginally productive sites occurring onmetamorphic rock will likely exhibit high-er second-growth productivity followingharvesting and site treatments, comparedwith a similar site on granodioritebedrock.

Note that two variations of the modelare presented—one emphasizing forestproductivity and one emphasizing bio-mass allocation. As indicated by the soilecology, moss productivity, and succes-sion studies, a switch in biomass alloca-tion from trees to mosses (and otherunderstorey vegetation) occurs as sitesprogress along the (slow) trajectory oforganic matter accumulation and declin-ing tree productivity. Bogs and bog forestsare often referred to as “low productivity.”They are, however, highly productive ifone considers the annual rates of totalbiomass accumulation measured in theseecosystems (see section 4.3.3).

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The classification and inventory compo-nent of the HyP3 Project serves as the linkbetween the hydrology and ecosystemprocess components, and the applicationof results across the north coast. The proj-ect has used the Biogeoclimatic EcosystemClassification () system (Pojar et al.1987) as the framework to make ecologi-cally based forest management recom-mendations. uses the site series toclassify forests for management purposes.Ecosystem classification is invaluable forchoosing appropriate sites for in-depthstudies, and also for extrapolating theresults to other similar sites throughoutthe north coast.

We conducted sampling in old-growthand second-growth forests to collect base-line information on tree growth and siteproductivity throughout the range offorested site series in the CWHvh2. Forestharvesting in the CWHvh2 has largelybeen limited to the higher-productivityforest types. For these sites, we haveregeneration and site index data from sec-ond-growth and old-growth forests, whichprovide information on regeneration andproductivity under full-light and partial-light conditions. On the lower-productivi-ty sites (CWHvh2/01, /11, and /12), fewsecond-growth stands exist; therefore, to

establish baseline growth patterns andrates for these sites, we combined the lim-ited site index and “years to breast height”sampling data available for second-growthstands with stem analysis of trees in old-growth stands.

At each of the HyP3 study sites, timbercruising was carried out to quantify standstructure, species composition, and grossand merchantable volume. Several forestmensuration attributes are summarizedfrom these data for each of the CWHvh2site series studied.

A review of rare, or otherwise threat-ened or imperiled ecosystems of theCWHvh2 is presented to examine anypotential impacts on these ecosystems that might result from expanding forestryoperations into the lower-productivityforest types.

A predictive ecosystem mapping ()model was developed for the outer coast.The resulting maps identify the site seriesmost likely associated with each forestcover polygon. These maps help to estab-lish the extent and location of potentiallyoperable low-productivity cedar–hemlockforest types. Site series productivity datacan also be combined with these maps toaid in growth and yield analysis for the.

5 CLASSIFICATION AND INVENTORY

5.1 Introductionand Approach

The system classifies sites within eachsubzone into a range of site series depend-ing on relative soil moisture and relativesoil nutrient regimes (see Figure 2.7).Within the CWHvh2, the HyP3 Project ismostly concerned with lower-productivityforests with mesic and wetter moistureregimes, and medium to poor nutrientregimes on the edatopic grid; the siteseries representing these forest types are:CWHvh2/01 (Western Redcedar –Western Hemlock – Salal) and CWHvh2/11(Western Redcedar – Yellow-cedar –Goldthread) (Banner et al. 1993). To draw

the necessary comparisons between forestproductivity and soil moisture–nutrientrelationships, study transects includeother common site series within theCWHvh2.

Depending on the soil developmentand the site series, three phases of siteseries are recognized in this subzone(Banner et al. 1993). 1. Mineral phase: occurs on sites with col-

luvial, morainal, weathered bedrock, orfluvial deposits (> 10 cm).

2. Lithic phase: occurs on sites with anorganic veneer over thin (< 10 cm)

5.2 Site SeriesDescription

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mineral soil over bedrock or boulders.3. Peaty phase: occurs on sites with a

peaty veneer or blanket (> 10 cm) overbedrock.

5.2.1 Zonal forests Zonal forests(CWHvh2/01; Western redcedar –Western hemlock – Salal) have relativelylow tree stature, open canopies, and well-developed shrub layers compared withproductive forests (see Figure 2.3 andFigure 5.1). These forests are found on arange of sites from upper to lower slopes.The soils are usually imperfectly drainedPodzols and Folisols with relatively deeporganic horizons in comparison to theunderlying mineral horizons. The openscrubby forests are dominated by westernredcedar, yellow-cedar, and western hem-lock, with shore pine and mountain hem-lock abundant in some locations. Forestson the CWHvh2/01 site series often havelow productivity compared to zonal sitesfound in other CWH subzones (Banner et al. 1993).

5.2.2 Bog forests Bog forests(CWHvh2/11; Western redcedar – Yellow-cedar – Goldthread) are very extensive inthe CWHvh2, especially on the Hecate

Lowlands. These very open and scrubby“forests” are found on a variety of slopepositions, but mostly on gentle terrain;however, on poor bedrock these forestscan extend up considerable slopes in someareas. Soils are organic veneers or blanketsover bedrock or saprolite. The tree speciesare usually yellow-cedar and western red-cedar with some shore pine interspersed(Figure 2.4 and Figure 5.2). Forests on theCWHvh2/11 site series are of lower pro-ductivity than those of the CWHvh2/01(Banner et al. 1993).

5.2.3 Bog woodlands and open bogecosystems Bog woodlands (CWHvh2/12;Shore pine – Yellow-cedar – Sphagnum)and open bogs (CWHvh2/32; slope–blan-ket bog) are very common on the outercoast (Figures 2.5 and 2.6; Figures 5.3 and5.4). These woodland and bog complexesare typical of the subdued terrain of theHecate Lowlands where organic soils pre-dominate. A sparse tree cover of less than

. Zonal forest (CWHvh2/01), Oona River. . Bog forest (CWHvh2/11), DianaLake.

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10% is typical of the woodlands; scattered,very scrubby trees occur in the open bogs.The main tree species is shore pine, withsome yellow-cedar and western redcedar(Banner et al. 1993). Based on detailedvegetation sampling, Asada (2003b) iden-tified five sub-communites within theCWHvh2/32 open bogs (see section 4.3.2).

5.2.4 Productive forests Productive non-floodplain forests are represented by theCWHvh2/04 (Western hemlock – Sitkaspruce – Lanky moss), CWHvh2/05(Western redcedar – Sitka spruce –Swordfern), CWHvh2/06 (Western red-cedar – Sitka spruce – Foamflower), andCWHvh2/07 (Western redcedar – Sitka

spruce – Devil’s club) site series. Theseforests are most commonly located onsteep colluvial slopes, but are also foundon inactive coarse fluvium with freedrainage, toe slope seepage sites, deepmorainal soils, and shallow Folisols.CWHvh2/05 is restricted, almost exclu-sively, to areas of metamorphic or lime-stone bedrock. Depending on disturbancehistory and chance, varying mixtures ofwestern hemlock, western redcedar, Sitkaspruce, and amabilis fir dominate thesesites (Figure 2.2 and Figure 5.5). Comparedwith zonal sites, these site series occur onbetter-drained or more nutrient-rich soils,which results in higher-productivityforests (Banner et al. 1993).

. Bog woodland (CWHvh2/12), Diana Lake. . Open bog (CWHvh2/32), Diana Lake.

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5.2.5 Floodplain forests Productiveforests found on floodplains are site seriesCWHvh2/08 (Sitka spruce – Lily-of-the-valley), CWHvh2/09 (Sitka spruce –Trisetum), and CWHvh2/10 (Red alder –Lily-of-the-valley) (Figure 5.6). The threedifferent site series are distinguished bythe height and frequency of flooding ofthe high, middle, and low benches, respec-tively. The low benches (CWHvh2/10)have Regosolic soils, with a progression toBrunisolic and Podzolic soils occurring onthe less frequently flooded middle andhigh benches (CWHvh2/09 and /08). Sitkaspruce, western hemlock, and westernredcedar dominate the CWHvh2/08 siteseries; the CWHvh2/09 site series is domi-nated by Sitka spruce, while theCWHvh2/10 site series is dominated byred alder (Banner et al. 1993).

5.2.6 Swamp forests Swamp forests(CWHvh2/13; Western redcedar – Sitkaspruce – Skunk cabbage) are found inpoorly drained areas with mineral seepage.

. Productive upland forest (CWHvh2/06), Port Edward.

. Productive spruce stand on aCWHvh2/08 site, Barnard Creek,Princess Royal Island.

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These forests are localized in lower slopepositions and level areas sometimes overfluvial deposits, with organic blankets andveneers. The mineral seepage results in aricher nutrient regime and better forestproductivity than in the bog forests andbog woodlands (CWHvh2/11 and /12),which have a similar moisture regime.These forests are most often dominated bywestern redcedar, less commonly by Sitkaspruce, with a vigorous and consistentcover of skunk cabbage characterizing theunderstorey (Figure 5.7) (Banner et al.1993).

5.2.7 Drier forest and scrub Drier forests(CWHvh2/03; Western redcedar – Yellow-

cedar – Salal) are uncommon, but dooccur on some upper-slope and ridge-crest positions on Folisols over (mostlynutrient-poor) bedrock. Species composi-tion, stand structure, and productivity areall very similar to the CWHvh2/01 siteseries (Western redcedar – WesternHemlock – Salal). On the most exposed,dry rocky knolls and outcrops, the Shorepine – Yellow-cedar – Racomitrium(CWHvh2/02; Figure 5.8) site seriesoccurs. These shrubby, open habitats withvery thin soils typically occur on rock out-crops interspersed throughout open bogson the Hecate Lowlands (Banner et al.1993).

. Swamp forest (CWHvh2/13), Diana Lake. . Dry, windswept rock outcrop (CWHvh2/02),McCauley Island.

In British Columbia, the vast majority offorest land is covered with old-growthstands (“old” depends on the zone). TheB.C. Forest Service used data derived frominventory plots located in old stands toestablish a baseline measure of site qualityor productivity, commonly referred to as“site index.” Site index () is an estimateof potential tree height growth on a siteover a fixed period of time. In BritishColumbia, we use 50, or total tree height

at a breast height age of 50 years. The pro-ductivity of a site largely determines howquickly trees grow and thus volume pro-duction and merchantable rotation age. Inrecent years, extensive site index samplingof second-growth stands (< 120 years,Figure 5.9) indicates that site productivityestimates from the old-growth forestcover inventory underestimate actual siteproductivity of regenerated stands (Table5.1). Second-growth forests tend to grow

5.3 SiteProductivity

87

faster than projected by the inventory-based site index estimates derived fromold-growth stands (Nigh 1998; Nussbaum1998; Olivotto and Meidinger 2001).

Tree growth and thus site index isstrongly influenced by ecological site fac-tors such as soil moisture and nutrientregime. A significant relationship existsbetween site index and site series. The Site Index–BiogeoclimaticEcosystem Classification Project ()produced a database that summarizes siteindex estimates (from second-growth fielddata) by site series for coniferous treespecies in British Columbia (B.C. Ministryof Forests 2003). These data are collectedfrom second-growth stands in which treeshave regenerated under open conditions,and therefore the resulting site index esti-mates are believed to better representgrowth potential on these sites following adisturbance. On a sample of five mapsheets from the north coast, for example,current forest cover information showsthat more than 50% of the total land basehas a 50 of eight or less. Estimates ofproductivity for the same area using estimates puts just 4% of the landbase into this category (Olivotto andMeidinger 2001; see section 5.6 for a fur-ther discussion of ecosystem-based pro-ductivity and yield analysis). Althoughother factors will also determine operabil-ity, many areas on the north coast cur-rently listed as inoperable may indeed bemore productive than currently estimatedby the forest inventory and therefore havesome potential for sustainable forestry.

5.3.1 Site Index and Years to BreastHeight The site index values presented in

Table 5.1 summarize data collected over alarge area of the north coast in the last 10 years. The data include informationobtained from old-growth stem analysisplots from four locations, second-growthfoliar nutrient plots from 14 locations, and plots from 50 locations. Thesedata show that estimates of site productiv-ity from old-growth stands significantlyunderestimate second-growth site poten-tial (e.g., western redcedar old growth,CWHvh2/01 site series; 50 = 3.9 vs. second-growth 50 = 17.8; old-growthyears to breast height () = 50 vs. sec-ond-growth years to = 7).

. Second-growth CWHvh2 stand usedfor site index sampling, Khyex River.

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. Old-growth and second-growth productivity dataa for the CWHvh2, north coast of British Columbia. Site series numbersas per Figure 2.7 (see section 5.2 for site series descriptions).

Old Growth, Mean Site Indexb

Western Mountain WesternSite series Amabilis fir redcedar hemlock hemlock Shore pine Sitka spruce Yellow-cedar

01 3.9 3.0 2.7 4.8 4.7 4.0(1.9–10.5) (2.0–7.7) (1.3–6.2) (2.3–9.5) (2.5–5.7) (1.7–9.8)

04 2.9 5.2 3.2(1.7–5.0) (2.8–7.4) (1.7–5.3)

11 2.9 3.1 3.1 3.8 2.9(2.0–4.5) (2.3–3.9) (1.4–5.3) (1.8–7.1) (1.7–5.5)

12 3.3 3.0 2.0 2.8 2.4(2.5–4.5) (2.2–5.5) (1.9–2.1) (1.8–3.7) (1.7–3.5)

Old Growth, Mean Years to Breast Heightb


01 58 50 69 65 59 67 45(21–120) (15–124) (24–105) (9–173) (17–84) (27–89) (11–137)

04 70 37 61 34(12–163) (21–50) (6–158) (34–34)

11 73 72 73 51 73(32–137) (37–105) (40–159) (31–70) (32–158)

12 79 101 108 89 107(37–184) (38–178) (63–172) (39–174) (45–361)

Second Growth, Mean Site Indexc


01 17.8 18.0 16.6(13.5–22.3) (8.0–31.0) (13.5–21.0)

04 26.9 22.7 22.9 27.4(14.9–35.4) (17.0–34.3) (10.0–33.5) (19.5–40.8)

05 31.7 28.3(24.7–36.0) (24.4–32.8)

06 29.6 23.2 27.0 33.0(18.2–34.7) (18.9–26.6) (21.0–32.8) (23.1–42.4)

07 21.7 21.9 29.3(15.5–28.0) (11.1–36.2) (18.6–43.1)

Second Growth, Mean Years to Breast Heightc


01 7 6 5 6(3–11) (3–10) (3–6) (3–8)

04 7 8 5 5(5–12) (5–12) (3–9) (4–8)

05 6 5(5–8) (5–6)

06 6 10 6 6(5–11) (9–10) (5–7) (4–7)

07 10.0 6 6(9–11) (4–9) (3–11)

a Mean site index data: height (m) at 50 years (breast height age). Range of site index in parentheses.b Values derived from HyP stem analysis plots.c Values derived from HyP stem analysis samples and BC Forest Service SIBEC plots.

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To quantify and compare the volume andquality of timber across the spectrum ofsite series, timber cruises were done atthree HyP3 study sites (Diana Lake, OonaRiver, and Smith Island). Results present-ed in Table 5.2 are shown using a lowerlimit of both 7.5 and 17.5 cm . Differ-ences among the site series are most evi-dent in volumes and basal area, with theCWHvh2/04 site series having the highestgross and net volume, the most basal area,and trees with the largest . TheCWHvh2/01 and /11 site series are progres-sively lower for all of these measures.Stems per hectare followed the oppositepattern with the CWHvh2/01 and /11 siteseries having higher densities than theCWHvh2/04 sites. The number of snagsper hectare above 7.5 cm was higheston the CWHvh2/11 site series, followed bythe CWHvh2/01 and /04. Above 17.5 cm, the CWHvh2/04 site series had themost snags followed by the CWHvh2/11and /01. When compared to zonal sites inother CWH variants, the CWHvh2/01 siteseries contains the lowest volume perhectare and the highest number of snagsper hectare (B.C. Ministry of Forests2001).

Western redcedar contributes the mostvolume on the CWHvh2/01 and /11 siteseries, with lesser amounts contributed bywestern hemlock, yellow-cedar, and shorepine (minor amounts of Sitka spruce arefound in the CWHvh2/01) (Figure 5.10).Western hemlock, western redcedar, and

Sitka spruce, with some amabilis fir andminor amounts of yellow-cedar, dominatethe CWHvh2/04 site series. Stems perhectare by species follow similar trends to volume, except for the CWHvh2/04,where relatively few stems of Sitka spruceand amabilis fir (these species are mostlyrestricted to the upper canopy layers)make up the volume for these sites (Figure 5.11).

The stems per hectare by diameter class curves all show a similar and typicalreverse “J” shape (exponential distribu-tion), with many small trees and fewerlarge trees. The slopes of the curves exhib-it some differences, however, with theCWHvh2/11 and /01 site series showingsteeper curves as a result of fewer largetrees. Basal area diameter class distribu-tions by site series show clear differencesamong sites. Basal area on the CWHvh2/11site series is concentrated in the smallerdiameter classes, with very little basal areaabove 55 cm diameter (Figure 5.12). OnCWHvh2/01 site series, there is little basalarea over the 100 cm diameter classes, andon the /04 site series, the curve ends at 110cm. The peaks in basal area in the largersize classes on the CWHvh2/04 sites areproduced by a few large trees.

The distribution of trees by height classclearly shows the differences among thesite series with the CWHvh2/04 includingmore trees in the taller height classes thanthe CWHvh2/01 and /11 site series (Figure5.13). Merchantable trees on the

5.4 ForestMensuration

. Summary of average stand characteristics for the CWHvh2/11, /01, and /04 site series atthe Diana Lake, Oona River, and Smith Island study site areas

a Volume/ha (m3) Basal area/ha Average Site series n (cm) Gross Net (m2) Stems/ha Snags/ha (cm)

11 21 7.5 188.7 133.4 38.0 787 399 28.717.5 159.0 107.6 33.8 459 123 33.8

01 44 7.5 329.3 229.3 54.2 809 202 30.317.5 298.4 202.9 50.4 457 107 37.9

04 11 7.5 508.1 398.7 60.6 760 152 35.817.5 479.0 373.2 56.6 372 152 44.7

a Diameter at breast height values represent the lower diameter limit used in the cruise compilation. Siteseries numbers as per Figure 2.7.

90

400

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mer

chan

tabl

e vo

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11 01 04

Site series

Western redcedar

Yellow-cedar

Western hemlock

Shore pine

Sitka spruce

Amabilis fir

Totals

. Net merchantable volume per hectare (> 17.5 cm DBH) by site series and species at theDiana Lake, Oona River, and Smith Island study sites. Site series numbers as per Figure 2.7.

500

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s p

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Western redcedar

Yellow-cedar

Western hemlock

Shore pine

Sitka spruce

Amabilis fir

Totals

. Stems per hectare (> 17.5 cm DBH) by site series and species at the Diana Lake, OonaRiver, and Smith Island study sites. Site series numbers as per Figure 2.7.

91

6

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are

10 25 40 55 70 85 100 115 130 145 200

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. Basal area and stems per hectare (≥7.5 cm DBH) in diameter classes at the Diana Lake, Oona River, and Smith Islandstudy sites by site series: (a) CWHvh2/11; (b) CWHvh2/01; and (c) CWHvh2/04. Site series numbers as per Figure 2.7.

(a) CWHVh2/11

(b) CWHVh2/01

(c) CWHVh2/04

92

500

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All sites 11Sites01 Sites04 Sites

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350

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CWHvh2/04 Sites Western redcedarYellow-cedarWestern hemlockSitka spruceAmabilis fir

1 2a 2b 3a 3b 4a 4b 5 6

. Stems per hectare (≥7.5 cm DBH) in height classes by site series at all sites and by species at theDiana Lake, Oona River, and Smith Island study sites. Site series numbers as per Figure 2.7.

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CWHvh2/01 and /11 site series are concentrated in height class two, whileCWHvh2/04 sites contain many mer-chantable trees in height class three andfour. On all sites, there is a significantnumber of stems less than 7.5 cm (e.g., advance regeneration ) not tallied.

Species distributions in height classes(Table 5.3) vary greatly among site series.The CWHvh2/04 site series are dominatedby hemlock in all height classes, but hem-lock is especially dominant in the shorterheight classes because of its high shadetolerance and ability to regenerate well onorganic substrates. Hemlock also domi-nated the shorter height classes in theCWHvh2/01. Western redcedar was moreprominent in the taller height classes onthe CWHvh2/01 site series. On theCWHvh2/11 site series, western redcedar

was dominant in all height classes, withyellow-cedar and shore pine also promi-nent in the shorter height classes. A sum-mary of stand characteristics for all threesite series at each site is presented inTables 5.4, 5.5, and 5.6.

. Tree heights used for height classdesignations

Height class Height range (m)

1 0.1–10.42a 10.5–14.92b 15.0–19.43a 19.5–23.93b 24.0–28.44a 28.5–32.94b 33.0–37.45 37.5–46.46 46.5–55.4

. Summary of average stand characteristics for the CWHvh2/11 (Western redcedar – Yellow-cedar – Goldthread) site series at the three study sites

a Volume/ha (m3) Basal area/ha Average Study site n (cm) Gross Net (m2) Stems/ha Snags/ha (cm)

Diana 4 7.5 165.0 120.0 33.3 546 374 27.917.5 137.0 97.1 30.2 481 212 29.6

Oona 7 7.5 200.7 135.2 38.9 702 228 29.517.5 179.1 116.3 36.0 353 61 38.5

Smith 10 7.5 189.7 137.4 39.4 944 528 28.517.5 153.6 105.8 33.8 526 132 32.8

a Diameter at breast height (DBH) values represent the lower diameter limit used in the cruise compilation.

. Summary of average stand characteristics for the CWHvh2/01 site series (Western redcedar– Western hemlock – Salal) at the three study sites


Diana 8 7.5 429.0 288.1 69.8 1532 267 25.917.5 375.0 242.3 61.9 618 108 34.7

Oona 22 7.5 331.5 235.0 50.5 574 98 36.117.5 309.1 215.6 48.5 412 84.1 41.3

Smith 14 7.5 268.7 186.5 51.0 684 330 29.517.5 238.9 161.7 47.4 437 143 36.3


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As the HyP3 Project was analyzing thepotential of harvesting in previously inop-erable forests, the biodiversity implica-tions of including these forests in theoperable land base were investigated. Thiswas done at the ecosystem, plant commu-nity, and species levels.

5.5.1 Red- and blue-listed ecosystemsOver 200 rare ecosystems in BritishColumbia are listed with the ConservationData Centre () in Victoria. Many ofthese ecosystems are in the “old” structur-al stage of commercially valuable forests,or in mature forest and grassland ecosys-tems targeted for agricultural and urbandevelopment, especially in the southernone-third of the province.

A red-listed ecosystem is considered by the as “imperiled provinciallybecause of extreme rarity or because ofsome factor(s) making it especially vul-nerable to extirpation or extinction.” Ared-listed ecosystem typically has fewerthan 20 high-quality occurrences withinthe province. A blue-listed ecosystem mayhave from 21 to 100 occurrences, or isconsidered vulnerable to either large-scaledisturbance or small-scale, but chronic,human-caused disturbance. Both red- andblue-listed ecosystems can be either natu-rally rare, or depleted and rare because ofhuman activities.

Currently, the mainland portion of theVery Wet Hypermaritime Coastal WesternHemlock subzone (CWHvh2) contains 11

red- and blue-listed ecosystems (Table5.7). These forests fall into two groups:1. inland forests mostly on floodplains,

fans, and colluvial slopes; and2. forests that occur in salt-spray zones

along windward shores or in brackishshoreline habitats.Operational implementation of the

HyP3 project’s research findings does not,for the most part, pose significant or seri-ous risks to these forest ecosystems.Harvesting activities in the forests targetedby the HyP3 Project, however, couldimpinge on rare forest types if:• the stands targeted for harvesting are

accessed via roads built through rareforest types;

• the higher-productivity stands repre-senting red- or blue-listed ecosystemsare used to economically justify har-vesting of the lower-productivitycedar–hemlock forests occurring adja-cent to them; or

• camp facilities or log-sorting andbooming activities damage the rare for-est types.

5.5.2 Other rare or threatened ecosystemsSeveral additional rare, sensitive, or threatened ecosystems occur in theCWHvh2 that are presently not listed withthe . These ecosystems are either notlisted because of incomplete inventories,or because the -listed ecosystems use as a framework; many rare ecosys-tems have not been properly classified

. Summary of stand characteristics for the CWHvh2/04 site series (Western hemlock – Sitkaspruce – Lanky moss) at the three study sites


Diana 2 7.5 592.0 457.4 55.1 189 29 63.317.5 586.0 453.0 55.1 189 29 63.3

Oona 4 7.5 453.8 359.3 49.0 438 48 37.917.5 429.9 338.7 47.0 361 48 43.5

Smith 5 7.5 517.8 406.7 72.0 1246 621 31.717.5 475.3 368.9 64.8 469 271 42.0


5.5 BiodiversityConsiderations

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. Red- and blue-listed ecosystems of the hypermaritime mainland coast of British Columbia (adapted from B.C. Conservation Data Centre, 2004)

Biogeoclimatic Provincial Provincial Scientific name Common name Typical situation site unit ranka list

Group 1. Inland forests mostly on floodplains and alluvium/colluvium

Tsuga heterophylla – Picea sitchensis – Western hemlock – Sitka spruce – Alluvial/colluvial; CWHvh2/04 S3 BlueRhytidiadelphus loreus Lanky moss inactive coarse fluvium

Thuja plicata – Picea sitchensis – Polystichum Western redcedar – Sitka spruce – Alluvial/colluvial; limestone CWHvh2/05 S2S3 Bluemunitum Sword fern and metamorphics

Thuja plicata – Picea sitchensis – Oplopanax Western redcedar – Sitka spruce – Alluvial/colluvial forest CWHvh2/07 S3 Bluehorridus Very Wet Hypermaritime 2 Devil's club Very Wet Hypermaritime 2

Picea sitchensis – Maianthemum dilatatum Sitka spruce – False lily-of-the-valley High bench floodplain CWHvh2/08 S2 RedWet Hypermaritime 1 Wet Hypermaritime 1

Picea sitchensis – Trisetum canescens Sitka spruce – Trisetum Middle bench floodplain CWHvh2/09 S2 Red

Alnus rubra – Maianthemum dilatatum Red alder – False lily-of-the-valley Low bench floodplain CWHvh2/10 S3 Blue

Thuja plicata/Picea sitchensis – Lysichitum Western redcedar – Sitka spruce - Swamps on lower slopes CWHvh2/13 S3 Blueamericanum Skunk cabbage and depressions

Group 2. Sea-spray / Shoreline forests

Picea sitchensis – Kindbergia oregana Sitka spruce – Kindbergia Spray zone CWHvh2/15 S3 Blue

Picea sitchensis – Calamagrostis nutkaensis Sitka spruce – Reedgrass Spray zone CWHvh2/16 S3 Blue

Picea sitchensis – Polystichum munitum Sitka spruce – Sword fern Marine terraces CWHvh2/17 S3 Blue

Picea sitchensis – Malus fusca Sitka spruce – Pacific crab apple Estuaries, brackish sloughs CWHvh2/19 S3 Blue

a Provincial ranks. S1 = critically imperilled; S2 = imperilled; S3 = vulnerable; S4 = apparently secure; and S5 = secure.

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within the framework, or they havespecific attributes, such as bedrock geolo-gy, which make them special cases withina given site series.

Forested ecosystems Although yellow-cedar is common in the CWHvh2, moder-ately productive old-growth stands ofyellow-cedar, with healthy trees of goodform in height class four and five, are rare(Figure 5.14). They typically occur at mid-elevations (250–400 m) and harvesting(generally helicopter logging) has

occurred in many of them. A moderatelyproductive old-growth forest with goodamounts of both yellow-cedar and west-ern redcedar, including veterans, wasidentified at Stair Creek on DouglasChannel in the early 1990s. Ecosystemsrepresented included CWHvh2/01, /03,/04, /05, and /06. This area was proposedas an ecological reserve in 1992, and is stilla valid candidate for protection.

Yellow-cedar decline (i.e., the death ofmature yellow-cedar trees) over consider-able areas of southeast Alaska has beenrecognized as an ecological and manage-ment issue for many years (Hennon andShaw 1997) Although various factors areimplicated, including poor drainage andclimate change (linked to early springfreezing injury), the causal agents remainunclear and continue to be studied. Somenorth coast stands located at 300–400 melevations have recently been observed tohave symptoms of yellow-cedar decline(P. Hennon, U.S. Department of Agri-culture, Juneau, Alaska, pers. comm., Dec. 2004).

Forests on postglacial volcanic depositsare another category of regionally rareecosystem. Strikingly productive forests of western hemlock, amabilis fir, westernredcedar, and Sitka spruce occur on vol-canic cones at Lake Island and Kitasu Hill(Swindle Island), with deep well-drainedsoils of ash and other unconsolidatedmaterial. Somewhat similar forests occuron deep tephra soils at Crow Lagoon, acaldera near the mouth of KhutzeymateenInlet, and a sister caldera further upslope.All of these areas have been affected byharvesting.

Karst landforms with gentle (but freelydrained) topography can support produc-tive forests (Figure 5.15), although lime-stone bedrock is rare on the north andmid-coast of British Columbia. Karsttopography is a unique landscape, withunusual and distinctive physical featuresand hydrology. The associated ecosystemshave highly productive soils, which support

. Productive yellow-cedar stand on Mount Genevieve,Haida Gwaii/Queen Charlotte Islands.

97

populations of specialized invertebrates.Although the combination of productiveold-growth forests (CWHvh2/04, /05, and/06) on limestone-karst is very rare in themainland CWHvh2, harvesting hasoccurred in stands on limestone becauseof the relatively high productivity of thesestands. Except on karst, productive oldforests seldom occur on gentle topogra-phy, which usually supports low-produc-tivity ecosystems such as the CWHvh2/01,/11, and /12. Karst ecosystems are incom-pletely known in the study area. Theserare karst ecosystems may occur in therelatively common site series and thus theConservation Data Centre has not iden-tified them as rare.

We know of several well-developedkarst ecosystems in the CWHvh2:• Chapple–Emily Carr inlets on Princess

Royal Island

• northwest Aristazabal Island (and as yetunspecified areas at Kettle Inlet, SwitzerCove, Turtish Harbour–BorrowmanBay, south of Nob Hill; field assess-ments of these four areas are required)

• east side of Aristazabal Island (areaopposite the Ramsbotham Islands haskarst, but the limestone deposit wasquarried in the past, and recently hasbeen further explored)

• Kumealon Inlet (the karst here has beenlogged over, but more may exist in thevicinity); some impressive second-growth forests occur on limestone inthis area.Further field assessment and documen-

tation of karst ecosystems are necessary.

Non-forested ecosystems Although thenon-forested habitats we describe belowshould not be directly affected by HyP3

applications, we include them for com-pleteness, and because these ecosystemsare rare, sensitive, and play significantroles in regional landscape diversity.

All seabird islands and marine mam-mal rookeries and haul-outs are intrinsi-cally unique, and therefore singularly rare(Figure 5.16). Examples include: LucyIslands; Bonilla Island; North DangerRocks; Mud Island; Prince Leboo Island;the Moore, Whitmore, and McKenneyislands of Ecological Reserve 23; theDewdney and Glide islands of EcologicalReserve 25; and the Byers, Conroy,Harvey, and Sinnett islands of EcologicalReserve 103. Collectively, these islands arevery rare, biologically significant, sensitiveto disturbance, and threatened by oilspills, careless recreationists, fishermen,and introduced species; however, theseseabird and marine mammal islands willnot be directly affected by HyP3 activities.

All estuaries are unique and are excep-tionally biologically productive (Figure5.17). Ecologically, estuaries are considered“keystone” ecosystems; that is, ecosystemswhose influence on the surroundingwatershed and landscape is disproportion-ately large relative to their abundance.

. Productive Sitka spruce– western redcedar forest on limestonebedrock, Hamner Island.

98

. Kerouard Islands, south of Kunghit Island, Haida Gwaii/Queen Charlotte Islands.

. Tidal estuary, Kwatna Inlet, east of Burke Channel.

99

Estuaries are also very sensitive to marinepollution, excessive harvesting, and sus-ceptible to harvest-related damage fromlog booming, roads, and camp facilities.

The two largest and most importantand complex estuaries in the mainlandCWHvh2 are those of the Skeena andNass rivers. These big estuaries providehabitat for numerous species, such as:juvenile salmon, eulachon, crab, bears,trumpeter swan, brant, great blue heron,western grebe, and many other waterbirds, as well as rare plants and plantcommunities on brackish mudflats(MacKenzie and Moran 2004).

Other smaller estuaries in this sub-zone include the Koeye, Winter Inlet,Kumealon Inlet, Lowe Inlet, BarnardHarbour, and Codville Lagoon; the Koeyeis probably the most significant of thesmaller estuaries. Significant estuaries alsoexist in the adjacent CWHvm, includingthe Stagoo, Kwinamass, Quottoon,Kitikiata-Quall, Klekane, Khutzeymateen,Bay of Plenty, Laredo Inlet, and Kwatna.

High-salinity tidal marshes, mudflats,and eel-grass (Zostera marina) beds arealso very productive systems, and areespecially important as habitat for migra-tory and wintering water birds and fortidal invertebrates, such as clams and

crabs. These ecosystems typically occur asnarrow shoreline strips or small pockets.Large expanses of saline tidelands areuncommon and have high conservationvalues. Notable examples include Big Bayand Kitkatla Inlet (including Billy Bay).

Sandy beaches are another intrinsicallyrare type of ecosystem along the rocky,often steep, and predominantly low-energy shoreline of the north coast. Mostare very small pocket beaches, as on thewest side of Digby Island and on KitsonIsland; a few are medium-sized, such asthose on Tugwell Island. Large sand beach-es occur just south of Cape Caution, andon the west sides of Calvert (Figure 5.18),Campania (McMicking Inlet), andPorcher islands. These beaches are valu-able, not only because of their spectacularbeauty and Crown land status, but alsobecause the organisms associated withthem are sensitive to marine pollution.Tombolos on southwest Princess RoyalIsland (along Laredo Channel) and Finand Bonilla islands are rare landforms andsites of special cultural significance.

Although peatlands are common andextensive on the north coast, nutrient-rich, minerotrophic fens and marshes areuncommon, and almost never extensive inthe CWHvh2 (Figure 5.19). Rich sedgefens and marshes mostly occur as narrowfringes along sluggish streams and themargins of lakes.

5.5.3 Rare plant species or habitats Rareplant species occurring in the CWHvh2/01forests were investigated as part of theHyP3 Project. The focus of field investiga-tions was lichens and mosses because ofour general lack of knowledge about theseplant groups. During harvesting at theOona River operational trial, lichens andbryophytes were collected from felledtrees, and later examined for rare species(Williston 2003b). In addition, the generalarea of Oona River was assessed for rarespecies, or species growing on unusualsubstrates. These collections did not revealany rare or endangered species of . Sandy beach on the west side of Calvert Island.

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bryophytes or lichens (Geiser et al. 1994;Goward et al. 1994; Ryan 1996; Goward1996; Goward 1999); however, the resultsof this limited survey should not suggestan absence of these species in zonalforests.

Two species of normally terrestriallichens, Cladina portentosa ssp. pacificaand Cladina arbuscula ssp. beringiana,were observed growing as epiphytes onthe boles and lower limbs of shore pine in peatlands of north coastal BritishColumbia (Williston 2001). These lichenshave not been previously reported asdemonstrating an epiphytic habit; they are likely found as epiphytes in this areaowing to their abundance in adjacent ter-restrial habitats and the windy, humidmaritime climate, which provides suitabledispersal and growing conditions (P.Williston, Gentian Botanical Research;pers. comm., 2004).

Foliicolous lichens and bryophytes (i.e.,those that grow on the leaves [includingscales and needles] of vascular plants) are relatively rare in temperate NorthAmerica; they are known only from therainforests of the northwest part of thecontinent. Seventeen foliicolous lichensand bryophytes are reported from a singlewestern redcedar growing along the shore

of Porcher Island (Williston 2003b). Fourspecies are new to the foliicolous flora ofNorth America, including two lichens,one moss, and one liverwort (Table 5.8).Their presence reflects the distinctivelystable, mild, and very humid conditions incoastal rainforests of British Columbia.These forests support a long and favour-able season for the establishment andgrowth of foliicolous lichens andbryophytes.

Though foliicolous species are wellknown from tropical and subtropicalregions, the floristics and ecology of theirtemperate counterparts have been thesubject of only two studies. In 1943,Daubenmire documented eight foliicolouslichens from northwestern Idaho; 30 yearslater, Vitt et al. (1973) listed 16 lichens andfive bryophytes growing on living westernredcedar scale leaves from a few localitiesin coastal Washington and British Colum-bia. Whether the substrate specificitynoted among these organisms is related to nutrient enrichment, pH, or the lack of inhibitory compounds is not known.

The current list of red- and blue-listed vascular plants for the North CoastForest District does not contain any speciesthat are normally found in CWHvh2/01forests nor any species that may beregionally rare or at the limits of their dis-tribution, although these species are alsonot likely to occur on zonal sites (J. Pojar,Canadian Parks and Wilderness Society,Whitehorse, Yukon; pers. comm., 2003).

5.5.4 Animal species of conservation con-cern The investigation of rare animalspecies in the CWHvh2/01 was done byconsulting local wildlife biologists andusing the list of red- and blue-listedanimal species for the North Coast ForestDistrict. Three species were identified thatmay be sensitive to increased harvesting inthe CWHvh2/01 forests:1. the red-listed northern goshawk

(Accipiter gentilis ssp. laingi);2. the red-listed marbled murrelet

(Brachyramphus marmoratus); and

. Carex sitchensis fen near Prudhomme Lake, Prince Rupert.

101

3. the blue-listed coastal tailed frog(Ascaphus truei).While these species do not depend par-

ticularly on CWHvh2/01 forests, they mayface an additional threat if harvesting ratesincreased on the north coast. Research onthese species is ongoing in coastal British

Columbia. Some genetically unique, in-sular forms of species may also occur onnorth coast islands; however, little infor-mation exists about this aspect of thearea’s biodiversity (D. Steventon, B.C.Ministry of Forests, Smithers, B.C.; pers.comm., 2004).

. A comparison of foliicolous lichens and bryophytes from Porcher Island and those reportedby Vitt et al. (1973) from other coastal localities in British Columbia

Foliicolous Species Porcher Island Vitt et al. (1973)

LichensCandelariella vitellina (Hoffm.) Müll. Arg. +Catillaria bouteillei (Desm.) Zahlbr. +Cavernularia hultenii Degel. + +Cetrelia cetrarioides (Duby) Culb. & C. Culb. + +Tuckermannopsis chlorophylla (Willd.) Hale + +Hypogymnia physodes (L.) Nyl. + +Hypogymnia tubulosa (Schaerer) Hav. + +Hypotrachyna sinuosa (Sm.) Hale + +Lecanora pulicaris (Pers.) Ach. +Lepraria sp. + +Physcia tenella (Scop.) DC. + +Parmelia sulcata Tayl. + +Placynthiella sp. +Platismatia glauca (L.) Culb. & C. Culb. + +Ramalina farinacea (L.) Ach. + +Rinodina sp. +Usnea sp. + +Xanthoria candelaria (L.) Th. Fr. + +

LiverwortsFrullania franciscana M.A. Howe +Porella cordaeana (Huebener) Moore +

MossesOrthotrichum consimile Mitt. +Orthotrichum lyellii Hook. & Tayl. +Orthotrichum pulchellum Brunt. +Orthotrichum speciosum Nees +Ulota phyllantha Brid. +

An ecologically based inventory is re-quired to apply results from ecosystem-based studies such as those conducted forthe HyP3 Project. The terrestrial ecosys-tem mapping () methods developedfor British Columbia (Banner et al. 1996)provide the preferred level of mappingdetail and reliability in the application ofecosystem management approaches tolandscape units. For very large and remote

jurisdictions such as the coastal forest dis-tricts, however, detailed field-based isprohibitively expensive and will not beavailable for the foreseeable future.Alternatives to have been developedand piloted over the past several years inBritish Columbia and elsewhere. Theseapproaches use existing inventories, andknown or expected relationships betweenecosystem units (e.g., site series) and

5.6 PredictiveEcosystem

Mapping

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inventory attributes, to predict ecologicalmap units (Figure 5.20).

Ecologists and geographic informationsystem () specialists at the B.C.Ministries of Forests and SustainableResource Management in Victoria andSmithers co-operatively developed aPredictive Ecosystem Mapping ()approach called “EcoGen” (Meidinger et al. 2000; Figure 5.21). The result of thisinitiative is a predictive ecosystem map-ping model for the outer coast. To pro-duce predictive ecosystem maps for theNorth Coast , this model establishedrelationships between ecosystems and for-est cover, Terrain Resource InventoryMapping (), digital elevation models() and bedrock geology mapping,within the context of refined biogeocli-matic subzone mapping. These mapsidentify the site series most likely associat-ed with each forest cover polygon and thushelp to establish the extent and location ofpotentially operable poor- and low-sitecedar–hemlock forest types.

As part of the HyP3 Project, an EcoGenpilot was established near Prince Rupertinvolving 75 000 ha within five 1:20 000forest cover map sheets. Fieldwork deter-mined the relationships between site seriesand inventory attributes, such as forest

cover features, slope, aspect, water andriparian features, and bedrock type. Toproduce the final maps, knowledgetables, which were developed for each ofthe applicable biogeoclimatic units, wereused to run the polygon attributesthrough a knowledge engine (EcoNGen).These first draft maps received a field-based reliability assessment; subsequentrefinements to the knowledge tables led tomap revisions (Jones 2001). These finalEcoGen maps received another reliabilityassessment that involved polygon checksthroughout the area, and comparisonsbetween the EcoGen mapping and thedetailed mapping carried out at theDiana Lake and Smith Island intensivestudy sites (Jones 2001). This reliabilityassessment indicated that the EcoGen pre-dictive mapping was 67% accurate for the label matching the dominant ecosys-tem unit on the ground, and 80% accu-rate when the adjacent ecosystem unit(i.e., adjacent on the edatopic grid)(Figure 2.7) was deemed acceptable.

When the EcoGen initiative started several years ago, the existing availableinventories (forest cover, , bedrockgeology) were recognized as significantlylimited for use in predicting ecosystems.At that time, a accuracy of 65–70%

DEM (TRIM), FC, Terrain and Other Inventories

Remote Sensing – Satellite and Airborne

EcosystemClassification

and BECMapping

DigitalInformationSystems and

EnablingTechnologies

PEM Model PEM Map

Large-scale BEC

maps

• Knowledgebase tools

• Digital maps• Attribute

databases

• Field Guides• Maps• Reports

• GIS• Databases• Knowledge

management

. The predictive ecosystem mapping (PEM) procedure.

103

EcoGen Process

EcoPrep EcoNGen EcoMap• Prepare GIS

layers• Knowledge

basedevelopment

• Knowledgeengine

• Processesknowledgebase

• Producemaps anddatabases

EcoPrep involves:

1. Large-scale BEC

2. Selecting primary polygons(e.g., forest cover)

3. Creating secondarypolygons using slope andaspect classes

4. Creating additional GISlayers with informationto assess site series insecondary polygons

5. Creating knowledge base

Input coverages

BEC subzonevariant

Elevation class

Slope/aspectclass

Forest covertype

Terrain

Overlay

. The EcoGen predictive ecosystem mapping approach. GIS inventory layers are preparedand overlaid; then the attributes of the resultant polygons are run through a “knowledgetable” that is developed for each biogeoclimatic unit. Site series predictions are based onknown or expected relationships between polygon attributes and ecosystem characteristics.

was regarded as a reasonable goal. Recentaccuracy assessments of projectsaround the province range from 65–85%;therefore, the EcoGen results represent anacceptable and more cost-effective (a fewcents per hectare vs. a few dollars perhectare) alternative to mapping.Most importantly, EcoGen allows us toget maximum use out of existing invento-ries before we decide on where additionalfunds should be directed for more detailedground-based ecosystem inventories.

Based on the satisfactory results obtain-ed from our pilot EcoGen project on thenorth coast, we received additional fundsto complete EcoGen mapping for theentire North Coast (1.95 million ha),and incorporate further refinements to theknowledge tables and features. This mapping project is now completed(Jones 2003). Further refinements to thebiogeoclimatic mapping for the north coast(e.g., better linking of the mapping to the elevational base) are also complete.

104

An independent accuracy assessmenthas now been completed for the NorthCoast mapping (Yole and Cushon2003) and the results indicate that theCWHvh2 is 75% accurate. As the assess-ment did not follow the current provincialaccuracy protocol (Meidinger 2003), theresult is not directly comparable to othermap assessments. The result does appearto indicate, however, that the mappingcan be used to predict site series composi-tion of forest cover polygons and will thusbe a useful tool for determining the location of potentially operable poor- andlow-site cedar–hemlock forest types. The maps will also be of use for otherstrategic planning processes including theimplementation of ecosystem-based man-agement on the coast.

A yield analysis project using the fiveinitial EcoGen pilot map sheets is alsofinished (Olivotto and Meidinger 2001).This analysis used second-growth site pro-ductivity () data from the HyP3

Project (see section 5.3, for a more com-

plete discussion of site productivity issues)to assign site index values to ecosystempolygons. This ecologically based analysiswas compared with the traditional timbersupply analysis, which uses site productiv-ity estimates derived from the (largely old-growth) forest cover inventory. Applyingthe EcoGen model and second-growth siteindex data to the yield analysis resulted insignificant increases to the mid- to long-term harvest flow in the pilot area. TheLand and Resource Management Plan() Table for the north coast consid-ered the implications of using these recentecologically based, second-growth siteproductivity data for yield analysis. Onreviewing the “base case” North CoastTimber Supply Analysis, tablemembers decided to use the traditionalforest inventory productivity estimates,and to incorporate the latest site produc-tivity data in a “sensitivity analysis”(North Coast Government TechnicalTeam 2002).

105

The HyP3 Project established operationalresearch trials at Port Simpson and OonaRiver. The trial near Port Simpson, northof Prince Rupert, was established in 1990to examine second-growth productivity inthe poor cedar–hemlock forest type.Initially funded by South Moresby ForestReplacement Account () researchfunds, this study was subsequently takenover by the HyP3 Project in 1999. TheOona River operational trial is located onPorcher Island, south of Prince Rupert.

This is a more expansive trial and wasestablished in 1998 to test some of themanagement ideas gained from both thePort Simpson trial and the multitude ofresearch studies undertaken on CWHvh2/01sites around Prince Rupert. These twooperational trial sites are described inChapter 2 (sections 2.6.3 and 2.6.4). ThreeHyP3 extension notes also provide infor-mation on the Port Simpson and OonaRiver trials (Appendix 1; Shaw and Banner2001a and 2001b; LePage et al. 2002).

6 OPERATIONAL RESEARCH TRIALS

6.1 Introduction

The Port Simpson operational trial is con-cerned with improving site productivityon imperfectly to poorly drained sites.The trial addresses two specific issues:1. seedling growth response on artificially

mounded and unmounded microsites;and

2. seedling nutrition on five substratetypes created by mixing and moundingtreatments.In this study, we hoped to determine

the impact of manipulating soil mineraland organic content on seedling nutritionand growth. To do this, we compared treegrowth between mounded and unmound-ed sites. Although mounding has beenused for site preparation in other areas ofBritish Columbia (McMinn and Hedin1990), this is the first trial established inwet north coastal forests. Some baselinehydrological monitoring was also carriedout at the Port Simpson operational trialas described in Beaudry et al. (1994) andBeaudry and Sagar (1995) (see Chapter 3,sections 3.2.5 and 3.4.2).

6.2.1 Study area description and researchapproach The study area is located 30 kmnorthwest of Prince Rupert near the vil-lage of Port Simpson (see Figure 2.9),within the CWHvh2. The study area islargely dominated by the Western red-cedar – Western hemlock – Salal site series

(CWHvh2/01). The major tree speciesbefore harvesting included western hem-lock, western redcedar, and yellow-cedar,with minor amounts of mountain hem-lock, Sitka spruce, and shore pine. Meanheight and diameter at breast height() of main canopy trees were 20 mand 65 cm, respectively. Gross volume perhectare was 500 m3 and net volume perhectare averaged 280 m3.

Variability in soil composition andthickness is common on the outer northcoast. In general, the soils of the studyarea consist of deep surface organic hori-zons (average depth 52 cm). This organiclayer is primarily composed of foresthumus on drier microsites and sphagnumpeat on wetter sites. This layer usuallyoverlays a thin mantle of mineral soilwhich is often less than 50 cm deep. Thesoils are mostly classified as Podzolic andthe horizons are derived from metamor-phic bedrock (schist and gneiss).

The study area was skidder-logged in the late summer and fall of 1990.Following harvest, the treatment area wasdivided into eight plots (i.e., four plots asmounding treatments and four left ascontrols), with an average plot size ofapproximately 0.18 ha. A John Deere 790 excavator equipped with a bucketand thumb attachment created themounds (Figure 6.1a). The objective was

6.2 Port Simpson

106

to build the mounds by overturning onescoop of soil and then mixing the mineralhorizons with the surface organic hori-zons. Mounds averaged 0.5 m in heightand 1.5 m in diameter. Mound densityvaried from 250 to 670 per hectare. Themounding treatment resulted in five substrate types (Table 6.1). The twounmounded substrates are controls repre-senting post-harvest conditions typical ofpoorer forested sites of the north coast. Inthe mounded treatments, soil variabilityresulted in three substrate types differingby degree of mixing and mineral andorganic composition.

In the spring of 1991, mounded andunmounded plots were planted with equalproportions of western hemlock, westernredcedar, and shore pine. Height andcaliper of planted trees were measured in 1991, 1992, 1994, and 1996. In 1997,whole trees were collected from both themounded and unmounded sites (Figure6.1b). At that time, 63 trees were manuallyexcavated to compare root developmentbetween the mounded and unmoundedplots. In addition, 28 soil samples werecollected for chemical analysis, and foliarsamples of new growth were taken fromthe upper crown of 63 planted trees. Soiland foliar samples were collected fromeach of the five substrate types.

6.2.2 Port Simpson results Five yearsafter planting, shore pine and hemlockshowed significant treatment effects (p < 0.05). Both species exhibited a 30%increase in mean height growth and a66–68% increase in mean caliper growthon the mounded sites (Figure 6.2).Western redcedar, however, did notexhibit a significant difference betweentreatments (p > 0.05). Preliminary resultsshow western redcedar did marginally bet-ter on mounded sites in average heightgrowth, but differences in caliper growthwere negligible between treated anduntreated areas.

. Port Simpson mounding trials: (a) after completion of mounding in 1990; and (b) 6 years after planting.

. Substrate descriptions at PortSimpson mounding trial

Substrate Composition

A Undisturbed LFHa and LFH with surface disturbance (unmounded)

B Undisturbed peat and peat with surfacedisturbance (unmounded)

C Mineral mound with low organic incorporation

D Mineral mound with moderate to highorganic incorporation, usually humus

E Organic mound, dominantly O (peat)material

a LFH = forest floor horizons.

a b

107

Although no difference in root to shootratios was evident between treatments, themean weight of root and shoot biomassincreased on the mounds for all species.Western hemlock and shore pine both

exhibited significant increases in root andshoot biomass between treatments (Figure6.3). Both mean above- and below-groundbiomass doubled for western hemlock andtripled for shore pine on mounded sites.Western redcedar also showed increases in root and shoot biomass between treat-ments, but the differences were not signi-ficant (p > 0.05).

Rooting depth on mounded sites alsoshowed a significant difference for allspecies (Figure 6.4). Mean rooting depthwas 75–100% greater for all three speciesgrowing on mounded sites compared withunmounded sites (Figure 6.5). The meanlength of the longest lateral root was alsogreater on the mounds, especially forwestern hemlock (28% increase) andshore pine (37% increase). In many cases,lateral roots extended well beyond thelimits of the mounds.

In general, western redcedar performedpoorly compared with shore pine andwestern hemlock, and showed no signifi-cant difference in height and caliperbetween treatments (p > 0.05). Overallmortality throughout the study area was

200

150

100

50

0

Hei

ght

(cm

) —

Cal

iper

(m

m)

Cw Cw Hw Hw Pl Pl(m) (u) (m) (u) (m) (u)

Species (treatment)

Mean heightMean caliper

3

2

1

0

Dry

wei

ght

(kg)


Species (treatment)

Average weight of root

Average weight of shoot

. Mean height and mean caliper of western redcedar (Cw), western hemlock (Hw), and shore pine (Pl) 5 years after planting on mounded (m) and unmounded (u) plots at the Port Simpson study site.

. Root and shoot biomass of western redcedar(Cw), western hemlock (Hw), and shore pine(Pl) 6 years after planting on mounded (m)and unmounded (u) plots at the Port Simpsonstudy site.

300

250

200

150

100

50

0

Leng

th /

dep

th (

cm)


Species (treatment)

Average length of longestlateral rootAverage root depth

. Rooting characteristics of western redcedar(Cw), western hemlock (Hw), and shore pine(Pl) 6 years after planting on mounded (m)and unmounded (u) plots at the Port Simpsonstudy site.

108

also greatest for redcedar (68%) comparedwith western hemlock (26%) and shorepine (14%). The increased mortality andpoorer growth response was largely attributed to the poor condition of thecedar stock (i.e., low root to shoot ratios)and heavy deer browsing after planting(seedlings were not initially protected).Although these factors have complicatedthe interpretation of treatment effects onwestern redcedar, the biomass and rootgrowth data showed some positive trendsrelated to treatment.

Initial trends suggest that moundingtreatments can have a positive effect onshoot growth, above- and below-groundbiomass, and root development forseedlings planted on these imperfectly topoorly drained sites (Figure 6.5). Themounding treatment resulted in soil mix-ing that revealed some other importanttrends in seedling growth and nutrition.The variable thickness of mineral andorganic horizons, and the nature of thesoils throughout the study area, createdconsiderable variation in mound charac-teristics. We observed trends in seedlingresponse that reflected this variation insubstrate type, with the best growthoccurring on mixed mineral-organicmounds and the poorest growth response

on pure organic (especially peat, ratherthan forest humus) mounds.

Results of the foliar nutrient analysissupport these findings (Figures 6.6 and6.7). In general, shore pine needles fromseedlings growing on mineral mounds hadthe greatest needle mass and content of allmacro- and micronutrients. The mineral–forest floor mix of substrate D yielded a

. Root development of western redcedar growing on unmounded (left) and mounded (right) plots 6 years after plantingat the Port Simpson study site.

25

20

15

10

5

0

Nitr

ogen

(m

g p

er 1

00 n

eedl

es)

A B C D E

Substrate

. Nitrogen content of pine needlesfrom trees growing on fivesubstrate types (see Table 6.1) atthe Port Simpson study site.

109

slightly lower needle mass and content ofmacro- and micronutrients, followed bymounded peat (substrate E). Theunmounded peat of substrate B yieldedthe lowest foliar mass and nutrient con-tent of all substrates tested.

Because of the dramatic differences infoliar mass among the various substratetypes, foliar nutrient concentrations(expressed as a percentage of foliarweight) did not reflect the differences inproductivity. In situations like this (i.e.,where a series of treatments gives rise tosignificant differences in biomass produc-tion), expressing the foliar nutrient datain terms of content (milligrams per 100needles) instead of concentration avoidsthe “dilution” complications broughtabout by the biomass differences (Ballardand Carter 1986). Interpretations of foliarnutrient data are not straightforward inthese situations, but it is reasonable toconclude from the Port Simpson trial thatinitial productivity and nutrient uptake

has been improved by the moundingtreatments. Although this may be partiallyattributed to improvements to micrositedrainage, the mixing of mineral andorganic horizons, similar to the naturalturbation resulting from windthrow andlandslide events, is likely the more criticalelement in improving soil nutrientregimes (Bormann et al. 1995).

We recognize that the Port Simpsontrial is only a preliminary investigation.Future studies should focus on the differ-ences in tree species response to mixingand mounding treatments, acceptable levels of site disturbance, impacts onpaludification (see sections 4.3 and 4.4),and optimal treatment methodologies.Although not included in this trial, yel-low-cedar is an important species on thesesites and should be included in futureresearch. The trends we observed at PortSimpson helped direct the design of theOona River operational trial.

8

7

6

5

4

3

2

1

0

Mac

ronu

trie

nts

(mg

per

100

nee

dles

)

P K Ca Mg S

ABCDE

. Macronutrient content of pine needles from trees growing on five substrate types (seeTable 6.1) at the Port Simpson study site.

The Oona River trial was established with the overall objective of examining the ecological and operational feasibilityof harvesting and regenerating lower-productivity forests. This trial set out to:• Assess the feasibility of harvesting

lower-productivity westernredcedar–western hemlock stands.

• Test the efficacy of fertilization andmechanical site preparation treatmentsfor promoting the establishment andgrowth of natural and planted conifers.

6.3 Oona River

110

• Compare the factors affecting establish-ment and growth of western redcedarfollowing harvesting.

• Assess and compare the growth per-formance of planted and natural west-ern redcedar.

• Assess the nutritional status of seedlingsestablished on a variety of micrositeswith and without the application of fer-tilizer.

• Document the growth history and pro-ductivity in lower-productivity, old-growth western redcedar–westernhemlock stands and compare this withsecond-growth productivity on similarsites.

• Assess the quality of timber harvestedfrom these lower-productivity stands.

• Document end-product recovery andutilization rates.

6.3.1 Study area description and researchapproach The Oona River trial is locatednear the community of Oona River onPorcher Island, 40 km south of PrinceRupert (see Figure 2.9). The operational

area consists of two adjacent blocks thatcover a total of 17.6 ha (10.2 and 7.4 ha,respectively). The trial is also situatedwithin the CWHvh2 subzone, and includes three site series: Westernredcedar – Western hemlock – Salal(CWHvh2/01) covers approximately 84%of the harvested area; Western redcedar –Yellow-cedar – Goldthread (CWHvh2/11)covers 10%; and Western hemlock – Sitkaspruce – Lanky moss (CWHvh2/04) cov-ers 6%. Both blocks occur on gentle slopes(5–25%) with a southerly aspect. Soils areimperfectly to poorly drained and consistprimarily of organic , or peat veneersover saprolitic veneers (decomposedschistose bedrock). Soil depth varies from20 cm to over 100 cm. Stands in the areaare dominated by western redcedar, whichaccounts for about 50% of the volume,and western hemlock, with lesser amountsof yellow-cedar, Sitka spruce, and shorepine. Based on a pre-harvest timbercruise, gross and merchantable volumeswithin the CWHvh2/01 site series were 333 m3/ha and 235 m3/ha, respectively.

In 1998, timber cruising and ecosystemsampling were carried out within a 50-hacandidate area to identify sites dominatedby the CWHvh2/01 site series. Using theecosystem sampling data, together withfield notes and air photo interpretation,an ecosystem map was produced for thestudy area. Preliminary block boundarieswere laid out to include mainly theCWHvh2/01 site series (Figure 6.8).Additional cruise plots were establishedwithin both blocks to obtain moredetailed information on species distribu-tion, stand structure, and wood quality.Detailed soil depth and ecosystem map-ping was also conducted on a 50-m gridwithin each block. A 1:3000 ecosystem–soil depth map was produced for bothblocks to refine the original block bound-aries, identify wetter leave patches (mostlysite series CWHvh2/13 [Western redcedar– Skunk cabbage] and CWHvh2/11), andplan harvesting and silvicultural treatments.

Oona River

L. 6786

L. 2203

11

01

12

11

01

12

04

04

12

01

12

04

Inoperable Forest

Operable Forest

Research Trial

. Ecosystem map of Oona River study site showing preliminaryblock boundaries that primarily encompass the Westernredcedar – Western hemlock – Salal (CWHvh2/01) site series.

Block harvesting began in June 2000.Following a diameter limit approach, all western redcedar and yellow-cedarbetween 17.5 cm and 150 cm werefelled. Western redcedar and yellow-cedarless than 17.5 cm were retained forcrop trees in the next rotation, and thosegreater than 150 cm were retained asseed and wildlife trees. The majority ofhemlock and shore pine greater than 2 m

in height were also felled; since neitherspecies was considered as a crop tree forthe next rotation, leave-tree specificationswere not required. Hand-felling was com-pleted over several weeks. The main skidroads were constructed with an excavatorusing non-merchantable wood (rottenlogs, snags, and undersized stems) as cor-duroy material. One main skid road wasconstructed through the centre of eachblock, with short spurs constructed toaccess block extremities (Figure 6.9). Logswere “hoe-chucked” to the main skidroads using a 320L, wide-tracked (32-inch) excavator (Figure 6.10) and movedto the haul road by a low-ground-pressure(< 6 ) tracked skidder equippedwith chokers (Figure 6.11).

Following harvest, twelve 0.1 ha treat-ment plots were laid out across the twoblocks. Uniformity in slope, soil moisture,and soil depth were major criteria for plotselection. Areas dominated by peaty soils(mainly site series CWHvh2/11) were notincluded in the plots. The site treatmentsselected for the operational trial werebased on existing knowledge of ecosystemprocesses and the results of the researchtrial established on similar sites near PortSimpson (Shaw and Banner 2001a and2001b). The Port Simpson trial indicatedthat planted seedlings generally performedbetter on mounds which consisted of amixture of organic and mineral soil hori-zons. In addition, experience on northernVancouver Island (Prescott and Weetman1994) has shown good tree growthresponse to fertilization with nitrogen (N)and phosphorus (P). We, however,hypothesize that the addition of P alonewill enhance N availability by stimulatingthe nitrogen cycle (Cole and Heil 1981;White and Reddy 2000) (See Chapter 4,section 4.5.3).

The lower-productivity sites contain ahuge amount of organic material (e.g.,dead and down trees, humus layers, moss,and vegetation). Disturbance of the sur-face organic soil layers and the removaland/or mixing of excess organic material

111

. Block 1 at the Oona River study site showing the main corduroyskid trail.

. Excavator “hoe-chucking” logs to main skid trail at the OonaRiver study site.

112

can warm the soil, increase soil aeration,and subsequently improve nutrient avail-ability. Surface scarification could alsocreate better seedbeds for natural regener-ation of western redcedar. Based on theabove rationale, the following three sitetreatments were randomly assigned to theplots (4 replications of each):1. Light surface scarification, and raking

and piling of slash (Figure 6.12).2. Light scarification and raking (as above)

combined with applications of phos-phorus fertilizer at the rate of 75 kg/ha.

3. Spot-raking followed by mixing the

organic and mineral soil horizons toform low mounds (Figure 6.13).All mechanical treatments were carried

out using a wide-tracked excavatorequipped with either a five-fingered brushrake or a bucket. Disturbance in theremaining area of the blocks (excludingtreatment plots and trails) resulted onlyfrom logging activities (felling, forward-ing, and excavator travel).

Both blocks were planted with a mix-ture of western redcedar (61%) and yellow-cedar (39%) in April 2002. Todetermine optimal regeneration methodsfor these lower-productivity sites, we willexamine the factors that affect the estab-lishment and growth of both natural andplanted western redcedar seedlings. Thesefactors include substrate composition,degree of soil disturbance, proximity toseed trees and stand edges, vegetationcompetition, and deer browsing. After 5 years, we will also assess the nutritionalstatus of planted and naturally regenerat-ed trees, with and without the applicationof fertilizer. Within the blocks, we willmonitor the natural regeneration of allconiferous species (western redcedar, yellow-cedar, western hemlock, shorepine, Sitka spruce, and amabilis fir), andcompare the survival rates and growthpatterns of natural western redcedar andyellow-cedar with the planted stock. . FMC tracked skidder moving logs to the landing at the Oona

River study site.

. Excavator raking and piling slash in block 1at the Oona River study site.

. Mixed mineral and organic mound on aCWHvh2/01 site at the Oona River study site.

113

Heavy browsing of western redcedarseedlings by the large deer population onPorcher Island continues to impede thesuccessful artificial regeneration on opera-tional sites; therefore, all seedlings plantedwithin the treatment plots were protectedusing 122-cm ® rigid tubes, double-anchored with cedar and bamboo stakes.These protectors were also used through-out the remaining area within the blocks.Three other seedling protector designs(Growcone® tubes, Sinocast® cones, andFree-Grow® shelters) were also installedon a limited number of seedlings. (Figure6.14). We will monitor these protectors toassess their susceptibility to wind andsnow damage, and their effectiveness inpromoting seedling survival and growth.

To determine how second-growth siteproductivity compares with that of theold-growth forests on these low-produc-tivity cedar–hemlock sites, we neededsome background information on thegrowth history of the existing old-growthforest. Before harvesting, we identified 37dominant and co-dominant sample trees

for stem analysis (Figure 6.15). The sampletrees were used to gather growth historyand old-growth site productivity informa-tion to refine existing site index and rota-tion length estimates for these lower-productivity sites. We will compare thegrowth history data from the operationaltrial with data gathered from the SmithIsland and Diana Lake old-growth studysites and with ongoing growth studies insecond-growth stands.

One of the overall goals of the HyP3

Project was to assess the feasibility of con-ducting commercial forestry operationson these lower-productivity sites. Projectresearchers, therefore, recognized that, inaddition to ecological concerns, questionswould arise about the quality and value ofthe available timber. Two areas of concernwere identified:1. the utilization levels (volume and

grade) expected from the timber foundon these sites; and

2. the achievable levels of end-productrecovery.

. Seedling protectors tested at the Oona River study site: Free-Grow® (left), Sinocast®

(front right), and Growcone® (back right).

114

To address the first point, a detailedfield assessment of log quality was com-pleted. This assessment compared stan-dard timber cruise grades with gradesobtained from “call-grading.” Log gradesfrom a standard cruise are assigned by acomputer program that tallies pathologi-cal indicators and compares them with astandard database for timber growing onsimilar sites. With call-grading, each treein a cruise plot is physically checked forvisible pathological and quality indicatorsand sounded to determine the presence or absence of rot. A log grade is thenassigned in the field by the cruiser.Because very limited harvesting ofCWHvh2/01 sites has taken place, anassignment of standard cruise-based loggrades is highly suspect. To address con-cerns surrounding end-product recovery,the volume of dimensional lumber pro-duced at the Group Mills sawmill at OonaRiver was compared with the scaled vol-ume of logs entering the mill. The milling

trial used a random selection of log gradesand included logs from the #2, #3, and #4sawlog and #5 utility grades. For a com-plete description of log grades, refer toB.C. Ministry of Forests (1994).

6.3.2 Oona River results Pre-harvestecosystem mapping proved an effectivetool in helping to delineate block bound-aries. The irregularly shaped, relativelysmall blocks that resulted from followingthe boundaries of the CWHvh2/01 siteseries will not only help to promote thenatural regeneration of western redcedarwith seeds coming from adjacent stands,but will also blend well into the blanketbog–upland forest landscape pattern(Figure 6.16).

Although the Oona River trial consist-ed mainly of the CWHvh2/01 site series,soil conditions varied considerablythroughout the blocks—a situation thathad operational implications. For exam-ple, soil puddling and surface water pond-ing occurred in some flat or gently slopingareas, especially where soils were shallow.Excavator mixing and mounding treat-ments in these areas were more likely todegrade the site and produce negativehydrological impacts than to improvemicrosites for seedling establishment andgrowth. Therefore, in the wettest portionsof the block, the passes with the excavatorwere minimized and naturally elevatedmicrosites used for planting seedlings.Throughout the bulk of the blocks whereslopes were greater than 15–20%, the mix-ing and mounding treatments were moresuccessful in providing beneficial soil dis-turbance and improving micrositedrainage.

Lower-productivity coastal forests havea high degree of structural diversity withmany veteran trees and snags. The fellingof these non-merchantable trees duringharvesting operations can lead to verylarge accumulations of woody slash onsites that already have excessively deepsurface organic horizons. To reduce theamount of organic material (decaying

. Western redcedar sample treemarked for stem-analysis cutting.

115

wood) added to the forest floor, thesetrees should be left standing whereverpossible (Figure 6.16). Trees left as seedtrees and wildlife trees can contribute tohabitat diversity goals. Although thediameter limit approach used in this trialproved effective in meeting objectives forboth slash management and seed andwildlife trees, a liberal interpretation ofthe existing wildlife danger tree assess-ment guidelines was required. Developingharvesting guidelines for these lower-productivity sites will pose significantchallenges as the desire to leave as manyveteran green trees and snags as possiblemust be tempered with the need for safe-ty. Chapter 7 provides more details onharvesting and site treatment options andguidelines for these sites.

In the fall of 2003, survival and heightgrowth assessments of the planted westernredcedar seedlings took place in each ofthe treatment plots. Overall survival wasexcellent and exceeded 96% in all treat-ment plots (Table 6.2). This is especiallyencouraging because of the typically poor

. Average percent survival and height a (cm) of plantedwestern redcedar seedlings at Oona River

Plot no. Treatment Survival (%) Average height (cm)

C1 Control 98 51.8C2 Control 98 53.3C3 Control 100 46.9C4 Control 100 49.4Average 99.0 50.4

4 Mound 100 64.15 Mound 98 55.510 Mound 100 56.711 Mound 100 59.2Average 99.5 58.9

3 Rake and Fertilize 100 53.86 Rake and Fertilize 100 52.77 Rake and Fertilize 100 50.613 Rake and Fertilize 100 53.0Average 100 52.5

1 Rake 96 55.22 Rake 98 51.68 Rake 100 50.99 Rake 100 55.7Average 98.5 53.4

a Survival and height growth were measured after two growing seasons (3-year-old trees)

. Aerial view of block 1 at Oona River showing the irregular ecosystem-based boundariesand the individual and patch leave trees.

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survival rate of unprotected seedlingsplanted in nearby operational blocks andthe associated uncertainties in establishinga viable second-growth crop. Although itis too soon to examine the results forsignificant differences in height growth,some early trends were observed. Theuntreated controls showed the least heightgrowth and the mounded plots showedthe best growth (Table 6.2). Both theraked and the raked and fertilized plotshad similar growth, but averaged onlymarginally more than the control plots(Table 6.2).

Stem analysis of naturally establishedwestern redcedar growing in old-growthforests has shown that initial heightgrowth is very slow on these CWHvh2/01sites (see Table 5.1). Across all treatments,the average initial height growth rate ofthe planted seedlings in clearcuts isapproximately seven times that of the nat-ural seedlings in old-growth forests (17.9cm/yr vs. 2.6 cm/yr).

Current site index estimates in the for-est cover database are derived primarilyfrom measurements of old-growth stands.Most of the CWHvh2/01 sites are classifiedas “low” and have an assigned site indexof 10 m or less. Detailed stem analysis ofold-growth western redcedar growing onCWHvh2/01 sites at Oona River confirmsthat conifer growth in the existing forests

is indeed poor and that the actual siteindex averages just 4 m for trees thatregenerated within the undisturbed old-growth forest. Stem analysis also revealedthat, on average, these trees take 50 yearsto reach breast height under the old-growth canopy (see Table 5.1). Preliminarydata collected from second-growth standson the same site series at other locationssuggest, however, that the second-growthsite index for western redcedar is actuallycloser to 18 m and the average time toreach breast height is just 7 years (seeTable 5.1). Mounding or other site prepa-ration treatments may reduce this timeeven further. Although a site index of 18m is still relatively low for coastal forests,it is significantly higher than indicated bythe current forest cover inventory (8–10m). This information is encouraging and reinforces the belief that some level of disturbance to these sites will provide abeneficial boost to tree growth and forestproductivity. Indeed, some sites currentlyclassified as “inoperable” because of poorgrowth rates may well prove manageablein the near future.

Table 6.3 presents a detailed compari-son of log quality, as determined by cruiseand call-grade methods, for the trees har-vested from the Oona River operationaltrial blocks. The results indicate that thecurrent cruise compilation programs,

. Cruised and call-graded merchantable timber volumes (m3/ha), by log grade and species, from the Oona Riveroperational research trial

Western redcedar Yellow-cedar Western hemlock Shore pine Sitka spruce Total

Call Call Call Call Call CallLog typea Gradea Cruise grade Cruise grade Cruise grade Cruise grade Cruise grade Cruise grade

#2 Lumber F 0.6 0.6#2 Sawlog H 12.3 16.5 4.9 3.9 17.2 20.4#3 Sawlog I 2.5 9.5 1.7 2.5 3.7 6.6 13.2#4 Sawlog J 39.4 40.8 16.1 5.8 22.9 8.5 4.9 1.6 14.5 6.8 97.8 63.5#2 Shingle L 4.7 4.7#5 Utility U 53.0 16.3 4.0 13.9 24.7 12.0 0.8 4.4 4.8 86.0 47.8#6 Utility X 2.5 9.6 1.6 0.5 6.3 22.0 1.8 3.5 10.3 37.3#7 Chipper Y 13.6 25.3 0.7 2.2 1.7 14.9 0.7 1.1 4.5 17.0 47.5

Total 123.2 123.2 22.4 22.4 57.3 57.3 4.9 4.9 27.3 27.3 235.1 235.1

a For log type and grade definitions, see: http://www.for.gov.bc.ca/tasb/legsregs/forest/faregs/scalreg/sr-1.htm#part 1

http://www.for.gov.bc.ca/tasb/legsregs/forest/faregs/scalreg/sr-1.htm#part 1

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developed for more productive coastalsites, do not provide an adequate portray-al of the log-quality profile obtained fromharvesting lower-productivity westernredcedar–hemlock stands on the northcoast. For western redcedar, the biggestdifference between the cruised and call-graded volumes was the significantdecrease in #5 utility logs. Forty-nine per-cent of this volume was moved into higher-quality and more valuable logs (L grade orbetter). For western redcedar, the field-based method of call-grading resulted in a24% increase in the volume of sawlogs.For the other harvested species, significantdecreases resulted in the volume of saw-logs and a corresponding increase in thevolume of lower-grade utility and chipperlogs, again indicating the inadequacies ofthe current log-quality profile for thesesites (Table 6.3).

The western redcedar growing on theimperfectly drained zonal sites on theouter north coast are typically muchshorter and have a larger butt flare thanthose growing on better-drained, moreproductive sites. In addition, the tree topsare often dead (spike-topped). This type

of log profile presents a significant chal-lenge for any lumber processing facilitytrying to achieve acceptable utilizationlevels. When sawing these western red-cedar logs to produce dimensional lumber, the high degree of taper andnumerous large branch knots in the top of the tree, combined with the large buttflare, can result in significant waste. Initialresults of the Oona River milling datashow that of a typical tree producing three5-m logs, the total accumulated wasteaveraged 46% (27% from the butt log,14% from the top log, and 5% from thecentre log). Although the Group Millsfacility is a basic operation using a twin-bladed circular saw with a 0.25-inch kerffor primary breakdown, this amount ofwaste is still within the normal range formilling western redcedar. More modernfacilities typically experience total accu-mulated waste in the 45–55% range,depending on the log grade milled (P.Edwards, International Forest Products,pers. comm., 2004; M. Wilson, DeltaCedar Products Ltd., pers. comm., 2004).An increase in end-product recovery inour study would have been possible if:• shorter pieces of lumber (< 6 ft.) from

the butt log were utilized,• less one-inch material was cut, and• the primary headrig was a more

efficient, narrow-kerf bandsaw.If logs were processed in a facility with

true taper-sawing capabilities, even morevolume recovery would be possible.Despite the problems associated withmilling the logs, the quality of the westernredcedar dimensional lumber and sidingproduced from these lower-productivitystands is very high (Figure 6.17).

. Some redcedar siding and dimensional lumber produced at theGroup Mills operation at Oona River. Sawlogs were harvestedfrom the nearby operational trial.

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Marginally operable, low-productivitysites in the CWHvh2 belong primarily tothe Western redcedar – Western hemlock– Salal site series (CWHvh2 /01; Banner etal. 1993). Although there is a range of pro-ductivity and species composition withinthe site series, the vast majority of thesesites are currently outside the operableland base. At the upper end of the pro-ductivity spectrum for this site series, soil and vegetation conditions become transitional to the Western hemlock –Sitka spruce – Lanky moss site series(CWHvh2/04), which is currently includ-ed in the operable land base. At the lower extremes of productivity for theCWHvh2/01 site series, conditions aretransitional to the Western redcedar –Yellow-cedar – Goldthread site series(CWHvh2/11), in which standing woodvolumes are well below current and pro-jected operability limits (typically less than150 m3/ha).

We have summarized data from over400 ecological plots collected by the B.C.Ministry of Forests between 1978 and theearly 1990s, as well as additional data col-lected by HyP3 researchers between 1998and 2002. These data have been used todevelop better descriptions of these hyper-maritime ecosystems, especially for thelower-productivity forest types of interest

in this study. By combining this informa-tion with HyP3 Project results from ourintensive study sites and operational trials,we have defined a set of criteria to identifythose CWHvh2/01 sites with the greatestpotential for sustainable forest manage-ment (Table 7.1). These criteria include:depth and nature of mineral and organicsoil horizons, bedrock geology, overstoreyand understorey composition, and standvolume. Other information, such as loca-tion and accessibility, should be used incombination with these site factors todetermine overall operability.

Ultimately, these site identification criteria, and additional information onbedrock identification and silviculturalstrategies, will be summarized in a supple-ment to A Field Guide to Site Identificationand Interpretation for the Prince RupertForest Region (Banner et al. 1993). Thisinformation will help to assess lower-pro-ductivity cedar-dominated sites underconsideration for harvesting. These crite-ria are not absolute, however, and thefinal decision on operability must weighpositive indicators against negative ones.We will further refine the operability cri-teria with monitoring information fromthe operational trials as we gain moreexperience in these forest types.

7 MANAGEMENT INTERPRETATIONS

7.1 Identificationof Potentially

Operable Sites

A silvicultural system is a cycle of activi-ties by which a forest is harvested, regen-erated, and tended over time to meetstand or landscape management objec-tives. Traditional silvicultural systems,first developed in Europe during the1800s, generally reflect the type of regener-ation method employed and the extent ofthe original forest canopy structureremaining after the initial harvest (e.g.,shelterwood, seed tree, clearcut, stripcut). The primary management concern

of these systems is typically the produc-tion of timber. The vast majority of har-vesting in British Columbia has used theclearcut silvicultural system. Since theearly 1990s, partial cutting or selectionsystems were used to retain some portionof the original stand structure and toemulate the size and pattern of naturaldisturbance regimes. In the interior of theprovince, many of these “retention sys-tems” met a wide variety of ecological andsocial goals while still allowing for timber

7.2 SilviculturalSystems

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. Site identification criteria for determining operability on Western redcedar – Western hemlock – Salal (01)sites in the CWHvh2

Operable sites Inoperable sites

CWHvh2/01a, (01b), more productive sites may betransitional to CWHvh2/04a or 04b

CWHvh2/01c, (01b), sites often transitional toCWHvh2/11 or CWHvh2/13

Site series phasesa

Western redcedar, yellow-cedar, and western hemlockare the dominant tree species; Sitka spruce is uncom-mon and of low vigour. Forests are open with numer-ous spike-topped western redcedar.

Understorey dominated by Alaskan blueberry, oval-leaved blueberry, and red huckleberry, as well asabundant amounts of salal and false azalea. Lankymoss and step moss are the dominant moss species.Common green sphagnum and skunk cabbage areoften present, but not dominant.

Absence or scattered presence of Labrador tea, crow-berry, lingonberry, sedges, deer-cabbage, Indian helle-bore, Pacific reedgrass

Western redcedar, yellow-cedar, western hemlock, andshore pine appear scrubby and are largely limited to theshrub layer (≤ 10 m). Mountain hemlock and shorepine may be more frequent than on “operable” sites.

Presence of species indicating poor nutrient availabilityand wetter conditions, including Labrador tea, crowber-ry, lingonberry, sedges, deer cabbage, sphagnum mosses(especially common red sphagnum, common brownsphagnum, and fat sphagnum), common scissor-leafliverwort, Indian hellebore, and Pacific reedgrass.Greater dominance of common green sphagnum, andskunk cabbage. Dominance and high vigour of skunkcabbage indicates CWHvh2/13 (swamp forests); avoidharvesting.

Indicator plantspeciesa

< 30 cmForest floor horizons (LFH) dominate. Usually com-posed of fine roots, wood, bark, and other plantresidues from communities typically associated with“upland” sites. A well-developed H horizon is typical.Peat materials (e.g., residues from sedges and sphag-num mosses or other typically “wetland” species) areabsent or minimal.

> 30 cmPeaty organic (O) horizons dominate. These horizonsare largely composed of residues from sedges andsphagnum mosses or other plants associated with soilmoisture regimes 6–8, with water tables at or near thesurface for a significant period during the growing season.

Organic soil depthand composition

Mineral soil depth > 20 cm < 20 cm

Bedrock type schistgneissdioritegneissic diorite

granodioritequartz dioritedioritegneissic diorite

Minimum standvolume

≥ 230 m3/hab ≤ 230 m3/hab

Height class ≥ 3 ≤ 3

Other operabilityconsiderations

Sites include some more productive forest patches(usually site series 04) to increase merchantable vol-ume and balance costs.

Area is accessed by minimal disturbance through wetforests (site series 11, 12, 13) or non-forested wetlands(site series 31, 32, 33). Sites dominated by slopesgreater than 10%.

No higher-productivity sites (usually site series 04) arepresent in proximity to site.

Access cuts through significant patches of wet forest(site series 11, 12, 13) or non-forested wetland (siteseries 31, 32, 33). Sites dominated by slopes less than10%.

a Site series phases and plant common names as per Banner et al. 1993.b Minimum stand volume represents net volume of conifers and is based on a minimum DBH of 17.5 cm. These volumes are based on

results from the Oona River and Port Simpson operational trials. Operable volumes will vary depending on site-specific costs.

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harvest. On the coast of British Columbia,however, the species composition, ecolog-ical characteristics, and size of the timber,combined with the typically steep terrain,presented significant challenges for theapplication of partial cutting and reten-tion harvesting techniques. As a result, the use of partial cutting systems has beenlimited primarily to single- or group-selection cuts done by helicopter,although ground-based or cable systemshave been successfully used on the southcoast in recent years. On the central andnorth coast, however, modern experiencewith partial cutting (as opposed to oldselective or high-grading cuts done duringthe early 1900s) is very limited; harvestingon the lower-productivity cedar–hemlocksites has occurred only recently (e.g.,Kumealon Inlet over the past few years).These stands present several new opera-tional concerns that pose challenges forsustainable management. For this reason,we considered several silvicultural sys-tems, both traditional and non-tradition-al, during the planning of the PortSimpson and Oona River operational tri-als. While the primary silviculture objec-tive of both trials was to re-establish aproductive stand of commercially valuableconifers, another important objective atthe Oona River trial was to retain some ofthe original stand structure and biologicalcomplexity.

7.2.1 Block layout Pre-harvest ecosystemmapping of potential harvest units provedan effective tool for the accurate delin-eation of block boundaries. Air photointerpretation is a critical first step indefining the initial ecosystem boundariesand significantly reduces layout time inthe field. Block boundaries should encom-pass the CWHvh2/01 sites and exclude themuch wetter and typically inoperableCWHvh2/11, /12, and /13 site series. If thesesite series cover greater than 0.1 ha withinthe block, the areas should be flagged asleave patches and assessed for windthrowpotential before final layout. Leave

patches within the block will providestructural diversity, wildlife habitat, and agood seed source for natural western red-cedar regeneration. To increase the totalmerchantable volume harvested from anyone unit, it may be desirable to includesome patches of more productive forest(site series 04 or 05), typically found onsteeper slopes adjacent to the CWHvh2/01sites. Some features that determine oper-ability, such as soil depth and composi-tion and bedrock type, are not discerniblefrom air photos and, therefore, initialblock boundaries will require on-sitemodification. To reduce overall site dis-turbance and off-site hydrologicalimpacts, planned access routes to andthrough blocks should avoid areas of wetforest (site series CWHvh2/11, /12, and /13)and non-forested wetlands (site seriesCWHvh2/31, /32, and /33). Although notyet tried on these specific sites, it may bepossible to construct a temporary accessroad, or a trail across small areas of wetforest or bog, using geotextiles or geosyn-thetics. These products allow a more evendistribution of loads, stabilize and rein-force the soil matrix, and reduce rutting.Avoiding these areas entirely, however, isthe preferred option.

After establishing block boundaries anddelineating leave patches, plans should bemade to promote natural western red-cedar regeneration. Retention of westernredcedar seed trees throughout the blockis highly recommended. Western redcedarseeds are very light (up to 1.3 million seedsper kilogram), but do not travel very farfrom the parent tree (Burns and Honkala1990). To increase the likelihood of ade-quate seed dispersal, we recommend thatthe distance between a block boundaryand an individual seed tree (or group ofretained seed trees) be no more than 100m. Seed trees must withstand long-termexposure to wind, often severe on thesesites, and retain some amount of ahealthy, live crown. Thus, managers mustconsider a trade-off in this situation—seed trees with large, healthy crowns that

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will provide regular seed crops are moresusceptible to windthrow and damagethan those with thinner, less vigorouscrowns (Stathers et al. 1994). This is ofparticular concern when an isolated tree isleft. Small groups of trees provide for bet-ter long-term stability and are the pre-ferred option. Large veteran trees, eventhose with significant amounts of stemrot, can also play an important role asseed trees. These “vets” produce fewer andless frequent seed crops than younger,healthier trees, but are usually more stableand likely to remain standing duringsevere wind events. The size and locationof retained seed trees will ultimatelydepend on the stand structure present.

7.2.2 Harvesting To maintain or increasetree productivity on the CWHvh2/01 sites,canopy openings are needed to increasesunlight, soil warming, and nutrient avail-ability. Therefore, some form of clearcutwith retention harvesting system (e.g.,modified diameter limit) is required. To define a workable cutting regime, wehighly recommend obtaining additionalinformation on stand structure and com-position. We suggest conducting at leasttwo cruise plots per hectare (more if standcomposition and structure is highly vari-able) to collect additional data on diame-ter class distribution. These data willprovide a more complete picture of thespecies and size distribution present, andallow the setting of suitable diameter lim-its. Upper and lower diameter limits willdepend on size and species distributionand total volume on the site. A significantproportion of the largest diameter westernredcedar veterans should be retained asseed trees (see section 7.2.1). In addition,every effort should be made at the time of harvest to retain any advance westernredcedar regeneration. On these low-productivity sites, retaining veteran treesshould not lower the total harvest volumesignificantly as these stems typically havehigh levels of stem rot and provide little,

if any merchantable volume. Larger veteran stems located on the richer sites(e.g., CWHvh2/04, /05) harvested in con-junction with these low-productivitystands can be cut. Although specific selec-tion criteria should be determined on ablock-by-block basis, the upper limit onthe CWHvh2/01 sites typically averages100–150 cm . Depending on futurestand structure goals, merchantable shorepine can either be removed or retained;however, under the Forest Planning andPractices Regulation (Section 46 [2])shore pine is only considered an “accept-able” crop species, and thus seed treeretention is not recommended. If westernhemlock will be a commercial componentof the next crop, all mistletoe-infectedhemlock stems higher than 2 m must beremoved. If the hemlock is not infectedwith mistletoe, its retention can act as awind buffer for western redcedar seedtrees, enhance visual quality, or improvewildlife habitat values. Hemlock retentionwill also maintain some canopy intercep-tion, and thus reduce the potential forwater table rise.

The wet soil conditions typically foundon lower-productivity sites, combinedwith the potentially positive benefits ofharvest and site preparation disturbanceson second-growth tree productivity, pres-ent some significant operational chal-lenges. Some level of site disturbance isbeneficial; however, to avoid site degrada-tion and off-site (hydrological) impacts,operators must recognize site- and weather-specific limitations. The CWHvh2/01 siteseries exhibits variable slope and soil char-acteristics and these variations result inconditions that respond quite differentlyto machine traffic. Flat and gently slopingareas with deeper organic soils, and areaswith thin organic veneers over bedrock,have greater potential for soil puddling,surface water ponding, and (over thelong-term) paludification. This is especial-ly true if operations are not suspendedduring very wet periods (> 75 mm

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precipitation in 12 hours). To ensure thesesites are not degraded, the current opera-tional shutdown guidelines may requirerevision. Low-ground-pressure, wide-tracked equipment (e.g., excavators with32-inch [82 cm] tracks) will minimize thenegative effects of machine traffic on thesesites, but still provide desirable levels ofsurface soil disturbance. This equipmentis capable of performing multiple func-tions, such as trail construction, log for-warding, slash piling, and site preparation.Corduroy roads, built of logging slash anddead and down woody material (non-merchantable), should be used for skid-ding. Using less material, secondary trailscan also be constructed and then pulledapart by the machine operator as the areais cleared of logs. This method not onlyminimizes the site disturbance associatedwith skid roads, but also aids in slashmanagement. During the harvesting phaseof the HyP3 Project, low-ground-pressuremachines (< 6 psi) such as the tracked skidder, proved ideal for trans-porting logs from the block to the landingor main haul road.

7.2.3 Site preparation treatments Withinthe CWHvh2, three phases of 01 site seriesare recognized: 01a – mineral, 01b – lithic,and 01c – peaty (Banner et. al. 1993). Themineral phase has proved the most suit-able for mounding or mixing treatmentsbecause more opportunities are availableto mix surface organic layers with subsur-face mineral horizons. On these sites, low,broad mounds are preferred over highermounds that result in deep pit–moundtopography, a condition which favours theestablishment of sphagnum mosses andsite paludification (see sections 4.3 and4.4). The lithic phase consists of forestfloor () horizons (sometimes over 40cm deep) occurring directly over bedrock.The peaty phase is composed of organicsoils (generally deeper than 40 cm)derived from sphagnum moss. On sites ofeither phase, mounding of pure organicmaterial is not expected to improve pro-

ductivity except, perhaps, through somemarginal improvement of surface soil aer-ation. Excessive machine traffic and sitepreparation on these non-mineral phaseswill likely lead to soil puddling, a decreasein the number of plantable spots, and adecline in long-term site productivity. Thebest strategy on the lithic and peaty phasesis to use naturally elevated micrositeswhen choosing plantable spots (e.g.,beside stumps). These sites will only besubjected to the surface disturbance creat-ed by harvesting activities, and these activ-ities should be curtailed during very wetperiods. Raking treatments to reduce theaccumulated organic matter and slash canbe applied to all phases of the CWHvh2/01site series as well as 04 sites. On sites seriesCWHvh2/11 (occurring mainly on peatysoils), initial treatment results indicatethat harvesting should be avoided wherev-er possible (see section 7.2.1).

Our operational trials show thatmachine operators must receive a basiclevel of training to recognize the soil con-ditions appropriate for applying site treat-ments. From an operational perspective(based on feedback from the machineoperators), harvesting and hoe-chuckingactivities should be combined with the sitepreparation activities to minimize thenumber of entries into the block. Afterassessing soil conditions by visual indica-tors and by test-probing with the excava-tor bucket or rake, operators can applythe appropriate raking or mounding treat-ments as they retreat from that area of theblock.

7.2.4 Planting Although harvesting andmechanically treating the CWHvh2/01sites should encourage natural regenera-tion of western redcedar, planting shouldbe carried out within 1 year of completingthe site treatments (i.e., allow mixed andmounded spots to settle over a winterbefore planting). To achieve the optimumplanting density, seedlings should beplanted on both the naturally raisedmicrosites and the artificially created

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mounds. Western redcedar is the mostecologically and economically suitablespecies for these sites and should make upthe majority of planted stems. Experiencewith planting yellow-cedar on these sitesis limited; however, it is a naturally occur-ring species and is considered acceptableas a minor component of the stand (e.g.,up to 20%). Although western hemlock is currently listed as a primary species onthese sites (Banner et al. 1993), planting is not recommended for the following reasons:• natural regeneration will occur on all

sites;• the cost of planting is not justified as

the species is of less economic valuethan western redcedar; and

• hemlock dwarf mistletoe (Arceuthobiumtsugense) can be a significant problemon these sites, thereby reducing overallyield and value.Browsing of planted western redcedar

by coastal black-tailed deer (Odocoileushemionus) is often very heavy on thesesites and seedling protection is thereforeconsidered mandatory. Although varioustypes of seedling protectors are available,the type selected should be at least 1.2 mtall. Manual removal of tree protectorssignificantly increases total establishmentcosts, particularly on remote, difficult toaccess sites. We, therefore, recommendprotectors that are designed to photo-degrade in 5–8 years (depending on sitelocation and growth rates). Since photo-degradation rates are quite inconsistent,the costs of follow-up site inspections andmaintenance must be included. Stake size

and quality are also critically important asa broken stake will result in the loss of theseedling. A 2.5 × 2.5 × 150 cm knot-freewood stake, preferably western redcedar,that is driven into the ground a minimumof 30 cm is recommended. Because highwinds and snow press often cause themost damage to seedling protectors, twostakes per protector may be required(Henigman and Martinz 2001). Some pro-tector designs require only a single stake,but may need some sort of additional pinto prevent the structure from shifting.Protection of seedlings should be doneconcurrently with planting.

As part of our efforts to protect plantedwestern redcedar seedlings from deerbrowsing, we recently initiated a researchtrial to determine the effectiveness andpracticality of using seedlings derivedfrom rooted cuttings taken fromunbrowsed, advance western redcedarregeneration. Research shows that deerbrowsing is sensitive to the levels ofmonoterpenes in the foliage (Vourc’h etal. 2001, 2002). The unbrowsed advanceregeneration may contain higher levels ofmonoterpenes, and cuttings taken fromthis root stock could retain this chemicaldefence. In addition, we are examiningnumerous nursery fertilizer regimes todetermine whether these affect a seedling’spalatability to deer. Some combination ofhigher levels of natural chemical defenceand altered foliage palatability may even-tually reduce the need to protect seedlingsfrom deer browse. Seedlings for these tri-als were planted at Oona River in thespring of 2004.

Through the HyP3 Project, we havelearned a great deal about the ecology,hydrology, silviculture, and managementof hypermaritime forests and related non-forested ecosystems. This knowledge hassupplemented our previous experiencegained from over 25 years of ecologicalresearch in coastal British Columbia. The

combination of pure science, involvingco-operation among specialists from relat-ed fields, and practical operational trialshas resulted in some initial managementguidelines with a solid ecological founda-tion. Nevertheless, we have just scratchedthe surface in the study of the long-termdevelopment of these cedar–hemlock

7.3 FutureResearchDirection

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forests following disturbance. Our stemanalysis work in old-growth forests pro-vided some clues about their developmentthat we have compared with initial growthrates in second-growth stands. We stillface uncertainties, however, about project-ing these growth rates into the future, andthese will only be lessened with continu-ing research.

Some of the HyP3 scientists haverecently initiated an ecosystem recoveryproject on the north coast of BritishColumbia that involves detailed ecologicalsampling in older second-growth stands.While searching for study stands that hadoriginated from forest harvesting over thelast century, several locations were discov-ered where 150–250-year-old, second-growth cedar stands had developed afterfire, probably Aboriginal burning. Manyof these stands represent second-growthCWHvh2/01 sites and will provide valu-able data on forest development followingdisturbance. This information, as well asobservations (by the authors) of a fewrecently regenerated cedar-dominatedstands on slash-burnt cutblocks, suggeststhat fire may be a potential managementtool on CWHvh2/01 sites and thus needsfurther research.

With the completed HyP3 research as a foundation, monitoring of our existingoperational trials must continue and newtrials established throughout the coast.Similar forest ecosystems to those studiedon the mainland coast occur on HaidaGwaii/the Queen Charlotte Islands, andthus opportunities exist there for theapplication of results and the establish-ment of operational trials. Our opera-tional trials on the mainland coast are alllocated on richer metamorphic bedrock.Although monitoring of some previouslyestablished second-growth stands on thepoorer granodiorites was also part of theHyP3 studies, additional trials on thiswidespread bedrock must be established.This is necessary to further test our initialconclusions that, compared with themetamorphic areas, these sites have

lower second-growth productivity andoperational potential (though still higherthan the old-growth stands indicate).Future operational trials should include ahydrological component to monitor soiland watershed hydrology 1–2 years beforeforest harvesting and for at least 2 yearsafter harvest. This was the intendedapproach at the Smith Island study site,where extensive hydrology data were col-lected; however, logistics, economics, andvisual constraints prevented harvesting onthis site. While we learned a great dealabout the baseline hydrology of hyper-maritime watersheds, which allowed us tospeculate informatively about the hydro-logical effects of harvesting, we still lackactual before and after scenarios. TheHyP3 studies now provide a wealth ofbaseline knowledge and data on which tobuild an effective pre- and post-harvesthydrological monitoring program withinfuture operational trial areas.

Many opportunities also exist for co-operative research with our counterpartsin southeast Alaska. Some joint field tripshave already permitted us to observe anddiscuss common forest ecology and man-agement concerns. Four high-priorityissues have emerged as having the greatestpotential for co-operative research efforts(D. D’Amore and P. Hennon, U.S. De-partment of Agriculture Forest Service,Juneau, Alaska, pers. comm., November,2004):1. Developing a common framework in

which to apply ecosystem classificationand mapping in coastal BritishColumbia and southeast Alaska.

2. Using age structure analysis to betterquantify disturbance histories acrossvarious hypermaritime stand and sitetypes; in particular, to better quantifythe role that wind has played in stand(and soil) development.

3. Quantifying second-growth productivi-ty in wet, lower-productivity foresttypes and better defining limits of oper-ability along the upland forest–bog for-est continuum.

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4. Better defining the problem of yellow-cedar decline (i.e., its extent, causes,implications, and potential solutions).Further development and refinement

of guidelines for these and other sharedforest ecology and management issueswould be significantly enhanced by cross-border co-operation in pure research andoperational trials.

Because operational trials are cost-effective and more likely to provideimmediate, practical results, they arebecoming the favoured research approach.We should not, however, ignore the needfor continued baseline research on ecosys-

tem function. Future research in thehypermaritime upland forest–blanket bogcomplex should also include componentsthat continue to examine the soil and veg-etation ecology, nutrient cycling, andhydrology of this fascinating landscape.

The research results and operationalrecommendations of the HyP3 Project,together with future research and opera-tional trial initiatives of this and relatedprojects, will hopefully contribute toeffective ecosystem- and science-basedmanagement in coastal areas of BritishColumbia.

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B.C. Ministry of Forests Research extension notes are available at: www.for.gov.bc.ca/rni/Research/Extension_notes/ Extension_Notes.htm

University of British Columbia Extension Series are available from the authors of thisreport.

Note # Title

B.C. Ministry of Forests Research Extension Notes38 Pattern, process, and productivity in hypermaritime forests: The HyP3 Project39 Basin hydrology and canopy interception in hypermaritime forests:

Issues and approach44 Excavator mounding to enhance productivity in hypermaritime forests:

Preliminary results45 Effects of soil mixing on foliar nutrient content of shore pine in hypermaritime

forests of northern British Columbia: Preliminary results48 The Oona River operational research trial49 Canopy interception in a hypermaritime forest on the north coast of British

Columbia50 Moss growth, production, and paludification in the hypermaritime north coast

of British Columbia51 Surface water discharge and groundwater storage patterns in a hypermaritime

bog near Prince Rupert, B.C.52 The blanket bog–upland forest complex of north coastal British Columbia:

Succession, disturbance, and implications for management54 Soil biogeochemical dynamics in hypermaritime ecosystems of north coastal

British Columbia

University of British Columbia Extension Series (Scientia Silvica)42 Regeneration, growth, and productivity of trees within gaps of old-growth

forests on the outer coast (CWHvh2) of British Columbia

For additional information on the HyP3 Project, please refer to the Web site at:www.for.gov.bc.ca/rni/Research/HyP3/hyp3-pg1.htm

APPENDIX 1 HyP3 Project-related Extension Notes

http://www.for.gov.bc.ca/rni/Research/Extension_notes/Extension_Notes.htm

http://www.for.gov.bc.ca/rni/Research/HyP3/hyp3-pg1.htm

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Aerobic – occurring in the presence ofoxygen as applied to chemical and bio-chemical processes; opposite of anaerobic.

Anaerobic – occurring in the absence ofoxygen as applied to chemical and bio-chemical processes.

Basal area – the cross-sectional area atbreast height (1.3 m) of all the stems ofinterest in a stand over a unit of land area;expressed as m2/ha.

Baseflow – the contribution that ground-water makes in sustaining water yields in awatercourse during periods of no rainfallor snowmelt.

Biogeoclimatic Ecosystem Classification() – a hierarchical ecosystemclassification system applied in BritishColumbia that describes variation in climate, vegetation, and site conditions.

Brunisol – a soil order containing soilsthat have sufficient development toexclude them from the Regosolic order;has a B horizon showing some soil genesis.

Bulk density – the mass of dry soil perunit volume. Also used in this report asmoss bulk density: g/cm of linear growthper square metre.

Climax vegetation – stable, self-perpetu-ating vegetation that represents the finalstage of succession.

Colluvium – unconsolidated materialmoved by gravity, often occurring at mid-dle or lower slope positions.

First-order stream – an unforked orunbranched stream. Two first-orderstreams flow together to form a second-order stream, two second-order streamscombine to make a third-order stream,etc.

Folisol – a soil order containing soilscomposed of upland organic materials,generally of forest origin, that are greaterthan 40 cm thick, or at least 10 cm thick ifover bedrock or fragmental materials.

Gleysol – a soil order containing soils thatare saturated with water and under reduc-ing conditions either continuously or for asignificant period of the year.

Hardpan – horizons or layers in soils thatare strongly compacted, hardened,cemented, or very high in clay content.

Hummock – a small, mounded rise oforganic matter and vegetation on a levelsurface.

Hydraulic conductivity – a coefficient ofproportionality describing the rate atwhich water can move through a perme-able medium.

Hydraulic gradient – the gradient orslope of a water table.

Hydrograph separation – a techniquethat uses the composition of water fromdifferent sources and in the receiving areato calculate the proportion of the totalwater coming from each contributingsource.

Lag time – has various definitions; usedhere to measure the difference betweenthe start of a rainfall event and a measura-ble response in a stream.

Lawn – a level area in a peatland with anelevation between that of a hummock anda hollow.

Macropore – a preferential flow channelwhose effect is most pronounced oninfiltration.

Minerotrophic – receiving nutrients fromgroundwater containing dissolved min-erals.

GLOSSARY8

8 Based in part on Cauboue et al. 1996

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Net primary production () – thegross primary production of plants minusthe biomass used in respiration by pri-mary producers.

Orographic precipitation – precipitationthat results from the lifting of moist airover an orographic barrier such as amountain range.

Overland flow – water that travels overthe ground surface to a point of concen-tration where turbulent flow occurs.

Paludification – process of bog expansioncaused by a gradual rise in water table, ordevelopment of a perched water table aspeat accumulation impedes drainage.Mineral soils are transformed into organicsoils as bog vegetation expands.

Peak flow – the maximum instantaneousdischarge of a stream or river at a givenlocation. It usually occurs at or near thetime of maximum flood.

Predictive ecosystem mapping () – a method of predicting ecosystem occur-rence on the landscape using availablespatial data and knowledge of ecologicaland landscape relationships. This infor-mation is used to automate the computergeneration of ecological map units.

Perched groundwater – a water tableformed by the perching of water on a rela-tively impermeable layer at some depthwithin the soil. The soil within or belowthe impermeable layer is not saturatedwith water.

Piezometer – an instrument for measur-ing the pressure head of liquids.

Podzol – a soil order containing soils inwhich the dominant accumulation prod-uct in the B horizon is amorphous mater-ial composed mainly of Fe, Al, and (or)organic carbon.

Preferential flow – water flow throughchannels in the soil and not the soilmatrix.

Quick flows – water that is immediatelyreleased from a watershed (see baseflow).

Redox – sometimes reactants gain andlose electrons, as in oxidation–reduction,or redox, reactions. In an oxidation–reduction reaction, one reactant is oxi-dized (loses one or more electrons) andthe other reactant is reduced (gains one ormore electrons).

Regosol – a soil order containing weaklydeveloped soils in which there is not a rec-ognizable B horizon at least 5 cm thick.

Retranslocation – the movement ofnutrients between older and newer foliagewithin a plant.

Saprolite – bedrock decomposed in situ.

Shelterwood – a silvicultural system thatinvolves the retention of a small numberof widely dispersed trees for seed produc-tion in order to regenerate a new age classin an exposed microenvironment.

Site index – a species-specific measure offorest productivity expressed in terms ofheight of trees at a specified age (usually50 years at breast height in BritishColumbia).

Site Index – Biogeoclimatic EcosystemClassification () – site index meas-urements tied to the system.

Site series – sites capable of producing thesame mature or climax plant communitieswithin a biogeoclimatic subzone or variant.

Soil pipe – subsurface channels parallel tothe slope that are sufficient in length toinfluence the flow processes at the hills-lope scale.

Terrain resource inventory mapping() – the provincial program to pre-pare computerized base maps for BritishColumbia at the 1:20 000, 1:250 000, and1:2 000 000 scales.

Terrestrial ecosystem mapping () –the stratification of the landscape into

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map units according to a combination ofecological features, primarily climate,physiography, surficial material, bedrockgeology, soil, and vegetation.

Time Domain Reflectrometry () – amethod of measuring soil water contentusing electromagnetic pulses.

Water table – the upper surface of a sub-terrestrial water saturation zone; the

elevation at which the pressure in thewater is zero with respect to atmosphericpressure.

Zonal site – a site that is intermediate insoil moisture and nutrient status within abiogeoclimatic unit. The vegetation on azonal site thus reflects the overridinginfluence of regional climate.

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Asada, T. and B.G. Warner. 2005. Surfacepeat mass and carbon balance in ahypermaritime peatland. Soil Sci. Soc.Am. J. 69: 549–562.

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PROJECT Pattern, Process, and Productivity of Coastal ... · study of pattern, process, and productivity in the hypermaritime forests of north coastal British Columbia. The project