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Importance, Preservation and Management of Riparian Habitat:

A SymposiumTucson, Arizona July 9, 1977

USDA Forest ServiceGeneral Technical Report RM-43

Importance, Preservation andManagement of Riparian Habitat:

A Symposium

Tucson, ArizonaJuly 9, 1977

Technical Coordinators:

R. Roy JohnsonNational Park ServiceandDale A. JonesUSDA Forest Service

Cosponsored by:Arizona Game and Fish DepartmentArizona-New Mexico Section, The Wildlife SocietyArizona State UniversityBureau of Land ManagementMuseum of Northern ArizonaNational Park ServiceU.S. Fish and Wildlife ServiceUSDA Forest Service

Influences of Riparian Vegetationon Aquatic Ecosystems

with Particular Reference toSalmonid Fishes

and Their Food Supply"William R. Meehan, Frederick J. Swanson, and James R. Sedell

3

Abstract.--The riparian zone has important influenceson the total stream ecosystem including the habitat ofsalmonids. Shade and organic detritus from the riparianzone control the food base of the stream and large woodydebris influences channel morphology. Temporal and spatialchanges in the riparian zone, the indirect influences ofriparian vegetation on salmonids, and the effects of man'sactivities are discussed.

INTRODUCTION

WHAT IS RIPARIAN VEGETATION?

Streamside vegetation strongly influ-ences the quality of habitat for anadromousand resident coldwater fishes. Riparian veg-etation provides shade, preventing adversewater temperature fluctuations. The roots oftrees, shrubs, and herbaceous vegetation sta-bilize streambanks providing cover in the formof overhanging banks. Streamside vegetationacts as a "filter" to prevent sediment anddebris from man's activities from enteringthe stream. Riparian vegetation also directlycontrols the food chain of the stream eco-system by shading the stream and providingorganic detritus and insects for the streamorganisms.

1Contributed paper, Symposium on the

Importance, Preservation and Management of theRiparian Habitat, July 9, 1977, Tucson, Arizona.

2The work reported in this paper was

supported in part by National Science Foun-dation Grant No. 7602656 to the ConiferousForest Biome and Grant No. BMS75-07333 tothe River Continuum Project. This is con-tr ibution No. 283 from the Coniferous ForestBiome and No. 5 from the River ContinuumProject.

3Research Fishery Biologist, USDA For-

est Service, Pacific Northwest Forest andRange Experiment Station, Forestry SciencesLaboratory, Corvallis, Oregon 97331; ResearchAss ociate and Research Assistant Professor,Oregon State University, Corvallis, 97331.

Riparian vegetation is at the interfacebetween aquatic and terrestrial environments.It has, therefore, been defined and examinedfrom a number of perspectives. Plant ecolo-gists speak in terms of riparian speciesand plant communities. The riparian zonemay also be defined geographically in termsof topography, soils, and hydrology. We pre-fer to take a functional approach; that is,to consider riparian vegetation as an y extra-aquatic vegetation that directly influencesthe stream environment.

Consequently, in defining riparian vege-tation we must consider the full scope of itsbiological and physical influences on thestream. Riparian vegetation regulates theenergy base of the aquatic ecosystem by shadingand supplying plant and animal detritus to thestream. Shading affects both stream temper-ature and light available to drive primaryproduction; therefore, the balance betweenautotrophy and heterotrophy is determined bymultiple functions of riparian vegetation.

Although imperfect, the stream ordersystem(Leopold et al. 1964) is a useful wayto classify elements of a drainage system.In small and intermediate-sized streams (upto about fourth-order) in the Pacific North-west, riparian vegetation exercises importantcontrols over physical conditions in the streamenvironment. Rooting by herbaceous and woodyvegetation tends to stabilize streambanks,retards erosion, and, in places, creates over-

137

/ above ground-above channel

in channel

streambanks

hanging banks which serve as cover for fish.Above ground woody riparian vegetation is anobstruction to highwater streamflow, sedimentand detritus movement, and is a source oflarge organic debris. Large organic debrisin streams (1) controls the routing of sedi-ment and water through the system, (2) defineshabitat opportunities by shaping pools, riffles,and depositional sites and by offering cover,and (3) serves as a substrate for biologicalactivity by microbial and invertebrate organ-isms (Triska and Sedell 1976; Swanson et al.1976; Sedell and Triska 1977; Anderson et al.in press).

The influences of riparian vegetation onconiferous forest stream ecosystems in thePacific Northwest are summarized in figure 1.In a functional approach to defining riparianvegetation, all floodplain vegetation as wellas trees on hillslope areas which shade thestream or directly contribute coarse or finedetritus to it are considered part of theriparian zone. In the Pacific Northwest,vegetation in the zone of riparian influenceincludes herbaceous ground cover, understoryshrubby vegetation (commonly deciduous), andoverstory trees on the flood plain (generallydeciduous) and on hillslopes (generally conif-erous).

VARIATIONS OF THE RIPARIAN ZONE INTIME AND SPACE

The character and importance of riparianvegetation varies in time and space. Temporalvariation involves patterns of vegetativesuccession following disturbances. Majorprocesses of vegetation disturbance includewildfire and clearcutting (important to up-slope vegetation) and damage due to impact ofsediment and floating ice or organic debrisduring flood flows. Spatial variation occursalong the continuum of increasing stream sizefrom small headwater streams to large rivers.

Temporal Variations of Riparian Zones

The effectiveness of a riparian zone inregulating input of light, dissolved nutrients,and litterfall to the stream varies throughtime following wildfire, clearcutting, orother disturbances (fig. 2). In the first

decade or two following deforestation, stream-side vegetation may increase in height growthand biomass more rapidly than upslope commun-ities. Shading of the stream by riparianvegetation gradually diminishes the potentialfor aquatic primary production until maximumcanopy closure. Deciduous shrubs and treeswithin the riparian zone will contribute most

Boundaries of RiparianZone

SITERIPARIAN VEGETATION

COMPONENT FUNCTION

canopy & stems

large debrisderived fromriparian veg.

roots

Shade-controls temperature &in stream primary productionSource of large and fine plant

detritus3. Source of terrestrial insects

I. Control routing of water andsediment

Shape habitat- pools, riffles,cover

Substrate for biological activity

Increase bank stability2. Create overhanging banks-covet

I. Retard movement of sediment,water and floated organicdebris in flood flows

floodplain stems & lowlying canopy

Figure 1.--Extent of riparian zone and functions of riparian vegetation as they relate to

aquatic ecosystems.

138

STREAM

5YEARS

DECIDUOUSTREES AND

11: g SHRUBS

10YEARS

30YEARS

CONIFERS

Figure 2.--Changes in the riparian zone throughtime.

of the litter inputs during early watershedrecovery. These deciduous inputs will morereadily decompose than coniferous litter whichdominates inputs late in watershed recoveryand in old-growth forests (Sedell et al. 1975;Triska and Sedell 1976).

The temporal development of riparian zonescauses a shift in the energy base of the streamfrom algae to deciduous leaves to a combinationof deciduous and coniferous leaves. The laststage in riparian succession is a complex mosaicof coniferous overstory, deciduous shrub layer,and herbaceous ground cover. Streams flowingthrough older, stratified forests receive thegreatest variation in quality of food fordetritus-processing organisms. Herbaceousvegetation is high in nutrient content, low infiber, and utilizable by stream organisms assoon as it enters the stream. Leaves from thedeciduous shrub layer are higher in fiber con-tent and take 60 to 90 days after enteringthe stream to be utilized fully by streammicrobes and insects. The conifer leaves take180-200 da ys to be processed. Thus there is asequencing of utilization of inputs from these

three distinctive riparian strata. The re-sults for the stream are rich and diversepopulations of a quatic insects which arekeyed into the timing and varied quality ofthe detrital food base.

Spatial Variation of Riparian Zones

A stream should be viewed as a continuumfrom headwaters to mouth (Vannote, personalcommunication; Cummins 1975, 1977). The in-fluence and role of riparian vegetation willvary with stream order and position along thecontinuum. Some broad characteristics ofstreams and rivers are depicted diagrammati-cally in figure 3.

Extensive networks of small first to thirdorder streams comprise about 85 percent of thetotal length of running waters (Leopold et al.1964). These headwater streams are maximallyinfluenced by riparian vegetation (the ratioof shoreline to stream bottom is highest), boththrough shading and as the source of organicmatter inputs. Even in grasslands, the dis-tribution of trees and shrubs follows perennialand, occasionally, intermittent watercoursesexcept where land use practices have resultedin removal or suppression of riparian vegetation.

These low light, high gradient, constanttemperature headwater streams receive signi-ficant amounts of coarse particulate matter(CPOM > 1-mm diameter). Their most strikingbiological features are the paucity of greenplant life or primary producers (algae andvascular plants) and the abundance of inver-tebrates that feed on CPOM (Cummins 1974,1975). Shredders reduce detritus particlesize by feeding on CPOM and producing feceswhich enter the fine particulate organicmatter (FPOM < 1-mm diameter) pool.

Although the transition is gradual andvaries with geographical region, the shiftfrom heterotrophy to autotrophy usually occursin the range of third- to fourth-order streams(fig. 3). Rivers in the range of fourth- tosixth-order are generally wide and the canopyof riparian vegetation does not close overthem. Direct inputs of CPOM from the riparianzone are lower in larger rivers because of thereduced ratio of length of hank to area ofriver bottom.

The importance of floodplain vegetation(mainly deciduous) increases relative to thehillslope species (mainly coniferous) and in adownstream direction. Generally this is sobecause the floodplain width increases down-stream and the canopy opening over largerstreams allows greater arboreal expression ofdeciduous riparian vegetation. Developmentof deciduous riparian trees is suppressed byshade along small streams.

139

COLLECTORS

GRAZERS

(0.3 METERS)MICROOES

SHREDDERSCPOM

(14EDATORS

cr

0cr 4=0 1.•

2 (1-2 METERS)

(PERIPH'fTON)PRODUCER

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ccW 4 (10 METERS)0cr

PAR < 1

00UCERS(VASCULAR

HYDROPHYTES)

CPOM

PRODUCERS(VASCULAR

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Figure 3.--A diagrammaticrepresentation of some of <X 5the changes that occur in UJrunning water systems OC

from headwaters to mouth. H C4'4 PRODUCERSThe organisms pictured are6 (PERIPHYTON)

possible representatives (50-75 METE

of the various functionalgroups occurring in the

OCsize ranges of streams and uj 7rivers. Although a large Q MICROBESnetwork of smaller tribu- OCtaries coalesce intolarger rivers, the system

8is shown diagrammatically <Xas a single headwater UJthrough all orders to the OCriver mouth (orders and

01approximate ranges ofstream or river width areshown at the left margin). 10

The decreasing direct in-11

fluence of the adjacentterrestrial vegetation of 12 (7•• METERS)the watershed and in-creasing importance ofinputs from upstream tributary systems is a basic feature of the conceptual scheme. The pro-portional diagrams at the right show the changes in relative dominance of invertebrate func-tional groups from headwaters to mouth. Important shredders include certain species ofstoneflies, caddisflies, and craneflies that feed on CPOM (coarse particulate organic matter)Dominant collectors are netspinning caddisflies, blackflies, clams, and certain midge specieswhich filter FPOM (fine particulate organic matter) from the passing water. Also, certainspecies of mayflies, midges, oligochaetes, and amphipods (may also function as shredders)gather particles from the sediments. Grazers or scrapers include certain species of caddisflies,mayflies, snails, and beetles. In addition to the fish shown at the left, the major predatorsare helgramites, dragonflies, tanypod midges, and certain species of stoneflies. The midregionof the river system is seen as the major zone of plant growth (algae, or periphyton, and rootedvascular plants) where the ratio of gross primary production (P) to community respiration (R)is greater than 1. Fish populations grade from invertebrate eaters in the headwaters to fishand benthic invertebrate eaters in the midreaches to benthic invertebrate and plankton feedersin the large rivers. (Modified from Cummins 1975).

EDATORS

0a_U-

2I

(ZOOPLANKTON)

140

FOOD BASE AND BIOLOGY OF FORESTED STREAMS

The food base for the biological comruni-ties of forest streams consists of leaves,needles, cones, twigs, wood, and bark. Thelarge boles which help shape the small streamare usually biologically processed in place.The input of bole material to the stream isnot a regular annual occurrence. Leaves,cones, twigs, lichens, and other componentsof fine litter have a reasonably predictabletiming of input to and export from streams.Of the organic material which falls or slidesinto first-order streams every year, only18-35 percent may be flushed downstream tohigher order streams. These streams are veryretentive, not mere conduits exporting materialsquickly to the sea. Sixty to 70 percent ofthe annual organic inputs are retained longenough to he biologically utilized by streamorganisms. Big wood debris dams serve aseffective retention devices for fine organicmaterial, allowing time for microbial coloni-zation and insect consumption of this material.Functionally the invertebrates of streamsflowing through forests have evolved to gouge,shred, and scrape wood and leaves and togather the fine organic matter derived frombreakdown of coarser material (Cummins 1974;Anderson et al.in press).

Woody debris and leaves, thetwo major allochthonous components enter-ing a stream from the riparian zone, operate

in different ways in relation to quantity,quality, and turnover time of standing crop.The leaves form a small pool of readily avail-able organic material, while the wood forms alarge pool of less available organic matter.The slowly processed wood also constitutes along term reserve of essential nutrients andenergy. The composition, metabolic structure,and nutrient turnover time of the particulateorganic pool effectively provide both flexi-bility and stability within the system.

The amount of debris processed in a de-fined reach of stream depends on two factors:(1) the nature of the debris (abundance andepecies of wood or leaves) and (2) the capacityof the stream to retain finely divided debrisfor the period of time required to completeprocessing. Debris undergoing utilization bystream biota may either be utilized fullywithin a stream reach or be exported to adownstream reach. Processing continues assmall debris moves along the drainage becauseexport from one reach constitutes downstreaminput. Processing includes both material usedmetabolically by bacteria and fungi and thosedebris pieces physically abraded by mineralsediment or by insect consumption. In allcases, the debris is broken into smallerpieces which increases the surface- to-volumeratio and makes a debris particle increasinglysusceptible to microbial attack.

Wood in streams is a substrate for bio-logical activity and it creates other habitatopportunities by regulating the movement ofwater and sediment. To measure the importanceof large organic debris from the riparian zonein streams, Swanson and Lienkaemper (unpublisheddata) examined several streams and measuredpercent of stream area in (1) wood, (2)wood-created habitat, principally depositional pools,and (3) nonwood habitat such as bedrock andboulder cascades. In a 245-m section of MackCreek, a third-order stream flowing throughan old-growth Douglas-fir stand in the westernCascade Range, Oregon, 11 percent of the streamarea is in wood, 16 percent in wood-createdhabitat, and 73 percent in nonwood habitat.Figure 4 shows an example of the distributionand quantity of debris in a section of MackCreek. In a first-order tributary draining10 ha, wood comprises 25 percent of the streamarea and another 21 percent is habitat createdby wood. Much of the biological activity bydetritus-processing and consumer organisms isconcentrated in the areas of wood and wood-created habitat. Each habitat type has adifferent faunal composition.

Wood Habitat Community

Wood habitat communities are distinctive.The primary utilizers are beetles, midges, andsnails. In addition to the food supplied tothe major wood eaters, the surface area and

large number of protective niches on woodafford considerable living space and conceal-ment. Wood is used for oviposition, as anursery area for early instars, for resting,molting, pupation, and emergence. Because ofits unique capillary properties, it affords anideal air-water interface where gradients oftemperature and moisture can be selected bydifferent taxa for various activities.

Wood-Created Habitat

The depositional areas behind large debrisare prime areas for processing leaf materialand the fine organic matter derived from wood.These areas are richer than the wood habitatcommunity both in numbers and biomass of inver-tebrates. Leaves and the shredders (primarilycaddis- and craneflies) are concentrated inthese areas. Many of the shredders feedinghere will use the wood habitat to molt, pupate,and emerge.

The difference in invertebrate biomass onleaves and wood is attributed primarily todifferences in food quality. Although bothare low in nitrogen compared with periphyton,seeds, or fresh macrophytes, the wood is sohigh in the refractory components lignin andcellulose that it becomes available at a veryslow rate. The greater surface area and pene-trability of leaves results in microbial con-

141

0 5 10

MA-2OI

r/z

\\t

METERS

WATER FLOW-

LOG: HT ABOVE LOW WATER, (M)

ACCUMULATION NUMBER

r=7..= POTENTIAL STREAM DEBRIS, ABOVE CHANNEL (M)

\:\

1

FLOATED ORGANIC DEBRISri TRAPPED SEDIMENT

MINIMUM TIME AT SITE, YR.

® LARGE ROCK

I RECENT DEBRIS (1976)

CC.3 BOULDER ISLAND

- CHANNEL BOUNDARY

SPRING CHANNEL

Figure 4.--Distribution of debris in a section of Mack Creek, western Oregon. Courtesy of George W.Lienkaemper.

ditioning occurring within months, comparedwith years for wood. Conditioning is a kr,factor in the debris becoming available asfood for the invertebrates.

RELATIONSHIP OF RIPARIAN VEGETATIONTO SALMONIDS

Direct Influences

The previous discussion has described howriparian vegetation contributes to primarystream productivity through input of organicmaterial and nutrients which are utilized byvarious components of the stream biota. Theserelationships directly affect the productionof fish b y establishing the basic componentsof the food chain which eventually lead to thefish themselves. Likewise, necessary portionsof salmonid habitat are created by large piecesof debris from the riparian zone. Logs anddebris jams create pools and protective cover.This type of habitat also provides communitiesof benthic organisms different from thoseassociated with the shallower and faster watersof riffles and runs. This increase in diver-sity of invertebrates provides a more useablefood base for the fishes, which depend to agreat extent upon them. A large part of thediet of fish in the family Salmonidae (thevarious Pacific salmon, trout, and char) isaquatic insects and other invertebrate organisms.

Indirect Influences

In addition to the effect of riparian zonematerial which directly becomes a part of thestream system, streamside vegetation has manyimportant indirect influences on the habitatof salmonids.

Water Temperature

The principal source of heat which raiseswater temperatures is direct solar radiation(Brown 196 0 ). Consequently, streamside vege-tation is important in maintaining water temp-eratures suitable for spawning, egg and fryincubation, and rearing of anadromous andresident salmonids. Several studies in thelast decade have demonstrated how streamsidevegetation directly controls water temperature(Levno and Rothacher 1967, Brown and Krygier1970, Meehan 1970, Burns 1972). The literatureis also rich with documentation of the effectsof streamside canopy removal on stream temp-eratures (Fall and Lantz 1969, Meehan et al.1969, Brown and Krygier 1970, Burns 1972,Moring 1975).

Stream temperature is directly proportionalto surface area and solar energy input, and in-versely proportional to streamflow (Gibbonsand Salo 1973). Therefore, small forestedstreams are the most susceptible to temperature

142

change. The insulating effect of riparianvegetation is thus of primary importance inmaintaining acceptable stream temperatures inthe many small streams which cumulatively pro-duce a significant portion of the salmon andtrout populations of the Western United States.

Sediment

Another major function of riparian vege-tation is to act as a buffer or "filter" againstsediment and debris which would otherwise bedeposited in the stream. Surface runoff is aprimary vehicle for the transportation of sedi-ment to streams from adjacent sources, eithernatural or man-created. The herbaceous communi-ties within the riparian zone are effective inreducing the impacts of this runoff, and thelarger shrubs and trees prevent larger debrisfrom entering the stream channel. The value ofstreamside vegetation for stream protection hasbeen quantified in economic terms by Everest(1975).

Sediment which affects salmonids occursin two general forms. As suspended sediment,it can he harmful if concentrations are highand persistent (Cordone and Kelley 1961).Under these conditions, silt may accumulateon the gill filaments and actually inhibit theability of the gills to aerate the blood,eventually causing death by anoxemia and carbon

dioxide retention.

Bedload sediment, however,probably limitssalmonid production more than suspended sedi-ment. Excessive deposited sediment reducesthe flow of intragravel water, which in turnlimits the supply of oxygen available to incu-bating eggs and alevins, and hinders the re-moval of metabolic waste products (Sheridan1962, Vaux 1962, Cooper 1965, McNeil 1966).Bedload sediment may also act as a physicalbarrier, preventing the emergence of newlyhatched fry up through the gravel (Koski 1966,Fall and Lantz 1969).

Another effect of sediment is the alter-ation of habitat used by aquatic insects(Wagner 1959) which directly relates to thegrowth and condition of the fish which utilizethem. Although biomass may not decrease, thespecies composition may change such that thenew forms are not as readily available to thefish.

Cover

The extensive rooting of herbaceous ripar-ian vegetation aids in streambank stabilization.As a result, where streamside vegetation isintact, the occurrence of undercut banks ishigher. This is prime habitat for trout andyoung salmon. Overhanging streamside vegeta-

tion also acts as escape cover and in someinstances as a deterrent against predation bybirds and mammals.

Insects

As discussed earlier, riparian vegetationcontributes to the food base of stream biolog-ical communities in the form of wood and otherorganic debris. In addition, streamside vege-tation is important in directly providing in-sects to the stream which then become part ofthe available fish food. Terrestrial insectswhich are associated with the various strataof the riparian zone become "accidental" fishfood items. Many of the aquatic insects usestreamside vegetation during emergence and inthe adult stages of their life cycle.

EFFECTS OF LAND USE PRACTICES

Many of man's activities affect theriparian zone to varying degrees. We mustconsider logging and road construction to beamong the most severe disturbances. Untilrecently it was common practice to clearcuttimber to the stream's edge. In addition toremoving the trees which provided shade tothe stream surface, the understory vegetationand ground cover were usually cut down orseverely disturbed. In recent years, theimportance of the smaller streams-has been

more fully recognized and buffer strips alongstreams are often left.

The riparian zone is also affected bylivestock grazing. In addition to croppingoff much of the herbaceous vegetation alongstreambanle s, livestock also use the smallershrubs and young trees as forage. As a result,much of the ground cover and many of the plantswhich provide shade to small streams are re-moved. The soil along the streams is compactedby trampling, and together with the removal ofthe "filtering'' plants a situation is createdwhich promotes the addition of fine sediment tothe streams. Wild ungulates also utilize theriparian zone, but their presence is much lessnoticeable than that of cattle and sheep. Aworkshop was conducted in Reno in May 1977 tobring together existing knowledge on the rela-tionships between livestock and fisheries,wildlife, and range resources. A large partof the material which was discussed at thisworkshop concerned the riparian zone, and willsoon he available.4

4USDA Forest Service, Pacific Southwest

Forest and Range Experiment Station, Berkeley,California (in press).

143

SUKMARY

The riparian zone is a very important areainfluencing the habitat of salmonids. Much ofthe wood which forms the food base for streambiota comes from the riparian zone. This samewood, when it falls or slides into a stream,has an important role in shaping the streamand creating its habitat types. Streamsidevegetation provides shade to the stream surface,thereby maintaining water temperatures accept-able to salmonid fishes. The roots of woodyand herbaceous plants provide streambank stabil-ity and help to create overhanging banks, animportant component of salmonid habitat.Streamside vegetation provides habitat for thelater life history stages of aquatic insectsand for terrestrial insects which accidentallybecome part of the food utilized by salmonids.

When the riparian zone is affected by man'sactivities, the quality of fish habitat willlikewise be affected.

LITERATURE CITED

Anderson, N. H., J. R. Sedell, L. M. Roberts,and F. J. Triska. In press. The role ofaquatic invertebrates in processing of wooddebris in coniferous forest streams. Am.Midland Naturalist.

Brown, George W. 1969. Predicting temperaturesof small streams. Water Resour. Res. 5(1):

68-75, illus.Brown, George W. and James T. Krygier. 1970.

Effects of clear-cutting on stream temper-ature. Water Resour. Res. 6(4):1133-1139,illus.

Burns, James W. 1972. Some effects of loggingand associated road construction on northernCalifornia streams. Trans. Am. Fish. Soc.101(1):1-17, illus.

Cooper, A. C. 1965. The effect of transportedstream sediments on the survival of sockeyeand pink salmon eggs and alevins. Int. Pac.Salmon Fish. Comm. Bull. 18, 71 p., illus.

Cordone, Almo J. and Don W. Kelley . 1961. Theinfluences of inorganic sediment on theaquatic life of streams. Calif. Fish &Game 47(2):189-228.

Cummins, Kenneth W. 1974. Structure and func-tion in stream ecosystems. Biosci. 24(11):631-641.

Cummins, Kenneth W. 1975. The ecology ofrunning waters. Theory and practice. In:Proc., Sandusky River Basin Symp., May 2-3,1975, Tiffin, Ohio, p. 278-293.

Cummins, Kenneth W. 1977. From streams torivers. Am. Biol. Teacher 39:305-312.

Everest, Fred H. . 1975. A method of estimatingthe value of streamside reserve trees. USDAFor. Serv. Siskiyou Natl. For., Grants Pass,Oregon, 12 p.

Gibbons, Dave R. and Ernest O. Salo. 1973.An annotated bibliography of the effects oflogging on fish of the Western United Statesand Canada. USDA For. Serv. Gen. Tech. Rep.PNW-10, 145 p. Pac. Northwest For, andRange Exp. Stn., Portland, Oregon.

Hall, James D. and Richard L. Lantz. 1969.Effects of logging on the habitat of Cohosalmon and cutthroat trout in coastal streams.In: T. G. Northcote (ed.), Symp. on salmonand trout in streams, p. 355-375, illus.Univ. B.C., Vancouver, 388 p.

Koski, K Victor. 1966. The survival of cohosalmon (Oncorhyrchus kisutch)from egg depo-sition to emergence in three Oregon coastalstreams. MS. Thesis, Oregon State Univ.,Corvallis, 84 p., illus.

Leopold Luna B., M. Gordon Wolman, and JohnP. Miller. 1964. Fluvial processes ingeomorphology. W. H. Freeman, San Francis-co, 522 p.

Levno, Al and Jack Rothacher. 1967. Increasesin maximum stream temperatures after loggingin old-growth Douglas-fir watersheds. USDAFor. Serv. Res. Note PNW-65, 12 p., illus.Pac. Northwest For, and Range Exp. Stn.,Portland, Oregon.

McNeil, William J. 1966. Effect of the spawn-ing bed environment on reproduction of pinkand chum salmon. U.S. Fish and WildlifeServ., Fish. Bull. 65(2):495-523, illus.

Meehan, W. R., W. A. Farr, D. M. Bishop, andJ. H. Patric. 1969. Some effects of clear-cutting on salmon habitat of two southeast

Alaska streams. USDA For. Serv. Res. Pap.PNW-82, 45 p. illus., Pac. Northwest For.and Range Exp. Stn., Portland, Oregon.

Meehan, William R. 1970. Some effects ofshade cover on stream temperature in south-east Alaska. USDA For. Serv. Res. NotePNW-113, 9 p., illus. Pac. Northwest For.and Range Exp. Stn., Portland, Oregon.

Moring, John R. 1975. The Alsea WatershedStudy: Effects of logging on the aquaticresources of three headwater streams of theAlsea River, Oregon. Part II - Changes inenvironmental conditions. Oregon Dep. Fishand Wildlife, Fish. R s. Rep. No. 9, 39 p.,illus.

Sedell, James R. and Frank J. Triska. 1977.Biological consequences of large organicdebris in Northwest streams. Logging Debrisin Streams Workshop, Oregon State Univ.,Corvallis, 10 p. March 21-22, 1977.

Sedell, James R., Frank J. Triska, and Nancy S.Triska. 1975. The processing of coniferand hardwood leaves in two coniferous foreststreams: I. Weight loss and associated in-vertebrates. Verh. Internat. Verein. Limnol.19:1617-1627.

Sheridan, William L. 1962. Waterflow througha salmon spawning riffle in southeasternAlaska. U.S. Fish and Uildl. Serv. Spec.Sci. Rep. Fish. No. 407, 20 p., illus.

144

Swanson, Fredrick J., Gecrge W. Lienkaemper, andJames R. Sedell. 1976. History, physicaleffects, and management implications of largeorganic debris in western Oregon streams.USDA For. Serv. Gen. Tech. Rep. PNW-56, 15 p.illus. Pac. Northwest For. and Range Exp. Stn.Portland, Oregon.

Triska, F. J. and J. R. Sedell. 1976. Decompo-sition of four species of leaf litter in re-sponse to nitrate manipulation. Ecnl. 57(4):783-792.

Vaux, Walter G. 1962. Interchange of streamand i,ntragravel water in a salmon spawningriffle. U.S. Fish and Wildl. Serv. Spec.Sci. Rep. Fish. No. 405., 11 p., illus.

Wagner, Richard. 1959. Sand and gravel oper-ations. In: Proc. Fifth Symp., Pac. North-west, on siltation--it sources and effectson the aquatic environ. Water Supply andWater Pollut. Control Pro g ., Portland,Oregon (mimeo).

145