Genetic Options for AdaptingForests to Climate Change

BYBRAD ST.CLAIRANDGLENN HOWE

S uccessful refor-estation requires

planted or naturallyregenerated seedlingsthat are well suited tothe site. Genetic stud-ies of forest trees pro-vide ample evidenceof large differencesamong seed sourcesin adaptive traits-traits such as the tim-ing of growth initia-tion and cessation,cold and droughthardiness, andgrowth rates.Furthermore,muchof this variation is related to the tem-perature and moisture regimes of theseed sources. In general, populationsare at or near their optimum for theirclimates. As a result, seed zones andseed transfer guidelines have beendeveloped and widely used that specifyusing relatively local seed sources forreforestation. These guidelines, howev-er, assume that climates are static overthe long term, an assumption that wenow know is unlikely.

The continued use of local seedsources will likely lead to a decline inthe health and productivity of bothplanted and native forests during thenext century given projected changesin climate. In a study of Douglas-fir inwestern Oregon and Washington, theauthors found that the continued useof local sources (i.e., current seedzones) would result in a high risk ofmaladapted stands by the end of thecentury. Douglas-fir populationsexpected to be adapted to the climateat the end of this century are located500-1,000 meters lower in elevationand 2-5 degrees further south in lati-tude. A study in British Columbia byTongli Wang and others based on anextensive set of lodgepole pine prove-nance tests indicated that productivitywould increase (up to seven percent)

given warming of about 1.5°C, butwould substantially decline givengreater warming, particularly in south-ern British Columbia, with some pop-ulations being extirpated. Productivitycould be increased by as much as 14-36 percent, however, by changing seedtransfer recommendations and mov-ing populations to their optimal cli-mates.

Concerns over impacts of climatechange on forest productivity andhealth, and questions about appropri-ate management responses, led to theformation of the Taskforce onAdapting Forests to Climate Change(http://tafcc.£orestry.oregonstate.edu).An accompanying article discussed sil-vicultural approaches to deal with cli-mate change. This article discussesgenetic options including manage-ment actions that could be taken toinfluence the natural or human selec-tion of genotypes, movement of geno-types across the landscape and con-servation of genetic diversity.

Planning for climate changeTo evaluate management options

for responding to climate change, wemust first evaluate the risk inherent inclimate change. Risk is defined as theproduct of the probability of occur-rence of an event and the impact ofthat occurrence. Both are difficult to

.- - --_ _- _. - _ .. _ ,--._ -Post-fire restoration may providean opportunity Jor reforestationwith mixed species or populationsadapted to a future climate.

predict. Although scientific consensuspredicts that temperatures will rise,projections for the Pacific Northwestvary considerably (0.1-0.6°C perdecade) with a best estimate of 0.3°Cper decade (http://cses.washington.edu/cig/fpt/ccscenarios.shtrnl#anchor2). Although projections for precipita-tion are less certain, warming withoutincreases in summer precipitation willresult in considerably more droughtstress. Managers must also considerthe risk of extremes in climates,including the potential for fall andspring cold events in the near-term,

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even if the future brings long-termwarming. To evaluate the impact of cli-mate trends and extremes, we need toknow about genetic variation in adap-tive traits. For some species such asDouglas-fir and lodgepole pine, wehave good information, but for others,particularly non-commercial species,we know much less.

Recommendations for planning forclimate change include:

• Develop your organization's per-spective on risk. Given the uncertaintyinherent in predicting future climatesand forest responses, each organiza-tion should evaluate their perspectiveon risk and needs. State and federalagencies may have different perspec-tives than private interests. For someorganizations, financial risks may beparticularly important, but for others,ecological risks may be their primaryconcern. Although the ecological,financial and social risks of differentmanagement options should be con-sidered, there is currently insufficientinformation to quantify these risksaccurately.

• Prioritize species and popula-tions for vulnerability to climatechange. Some species may be lesssensitive to climate change than oth-ers. For example, western white pineis considered a generalist because dif-ferences among seed sources are rela-tively small, but Douglas-fir is consid-ered a specialist because it has con-siderable seed source variation that isassociated with climate. Populationsat the southern boundaries of aspecies' range may be more vulnera-ble because there are no populationsfrom warmer environments that canmigrate into these areas as warmingoccurs. Small populations may be

more vulnerable owing to low geneticdiversity.

• Monitor for climate changeimpacts. Changes in species composi-tion, reforestation problems associatedwith drought, changes in the timing ofbud flush because of poor winter chill-ing, and increased disease and insectproblems may all be indicative of cli-mate change. Organizations shouldmonitor their forests and collect thedata needed to detect climate changeimpacts as they occur, and determinewhat their "trigger" should be for con-cluding that management approachesshould be changed.

• Manage for uncertainty. Oneapproach to managing for uncertaintyis to diversify. A diverse approachincludes incorporating both geneticdiversity and a diversity of silviculturalapproaches across the landscape. Thevaried ownership and management offorests in the western United Statesshould help.

• Plan your response. Responses toclimate may be 'reactive' or 'anticipato-ry.' If you plan to react to climatechange once adverse effects areobserved (i.e., based on your 'trigger'), itwould be wise to know exactly whatyour management responses will be.Some responses may be quick to imple-ment, but others may take years to planand carry out. For example, large firesmay provide excellent opportunities toadjust species and seed source compo-sition Viaplanting, but acquiring theappropriate seed sources may requireyears of advanced planning. Further-more, practices may need to bechanged to plant new species and seedsources in areas that have been regen-erated naturally in the past.

Genetic options for naturallyregenerated forests

• Maintain species and geneticdiversity. Genetic diversity providespopulations with the capacity toadapt to climate change via naturalselection. Existing genetic diversitycan be conserved by locating reservesin areas of high environmental het-erogeneity and high genetic diversity(such as might be found in mountain-ous areas with steep elevational gra-dients) and by using silviculturalpractices that make stands moreresistant to fire and pests, such asthinning or prescribed fire.

* Maintain corridors for gene flow.Genetic diversity may be enhanced innative forests by promoting gene flowthrough pollen and seed migration.Introduced genetic variation via geneflow from adjacent stands may increasethe frequency of adapted genotypesand allow for natural selection.

• Establish "genetic outposts."Stands that are genetically adapted tofuture climates may be planted adja-cent to native forests to increase thepotential for migration of pollen andseed into naturally-regenerated forests.A small number of genetic outpostsmay be sufficient, and commercialplantations next to native forests mayserve this function. The concept ofgenetic outposts is a departure fromthe previous view that 'pollen contam-ination' was considered detrimental toconservation objectives.

Although naturally-regeneratedforests may be made more resistantand resilient through silviculturalapproaches, plant populations maybecome increasingly maladapted andunable to keep pace with climatechange. Therefore, we should beginthinking about conserving ecosystemfunctions, not necessarily currentecosystems, and it may become neces-sary to use artificial regeneration inareas that were formerly regeneratednaturally to maintain vital ecosystemfunctions.

Genetic options for plantedforests

• Create seed banks for vulnerablepopulations. Given the potential forloss of species and genetic diversity,organizations should give greateremphasis to seed collections for long-

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term storage in seed banks. This is par-ticularly true for unique or isolatedpopulations that may be at anincreased threat from fire or pests.

• Move species and populations tomatch future climates. 'Assisted migra-tion, is the movement of species,provenances or breeding populationsfrom areas where they currently occurto new sites where they are expectedto be adapted in the future. Althoughlarge movements may not be wise atthis time, it may be wise to begin mov-ing genotypes from colder to warmerto environments within existing seedzones, and perhaps across adjacentseed zones.

• Mix provenances to hedge yourbets. The uncertainty of future climatesmay be mitigated by increasing genet-ic diversity through planting prove-nance mixtures. Mixtures may bedeployed at the stand level or theymay be deployed across the landscapeby planting different areas to differentprovenances.

• Plant at higher densities to allowfor natural and human selection bythinning. Planting provenance mix-tures at the stand level may be com-bined with higher planting densities toallow for higher mortality or the thin-ning of slow growing trees that showevidence of maladaptation.

• Select and breed trees for futureclimates. Genetic variation exists forcold hardiness, drought hardiness,growth phenology, and disease andinsect resistance. For species withintree improvement programs, it may bepossible to specifically select for traitssuch as drought hardiness that may beimportant in the future. Initiating abreeding program can, however, be along-term and expensive prospect,and silvicultural options may be morefeasible for some traits, for example,for new diseases or insects. Breedingfor broadly adapted genotypes mayalso be possible, although its efficacyhas not been tested.

Needed tools and researchWith funding from the U.S. Forest

Service Global Change ResearchProgram, the authors are currentlydeveloping an interactive web-basedtool that will allow users to displaycurrent seed zones or breeding zones,characterize those zones for climatevariables important to the adaptationof a chosen species, and show howthose zones may shift given alterna-tive future climate scenarios.

Furthermore, a national databasefor provenance test data is being initi-ated that will ensure that the datafrom many of the earlier establishedprovenance tests will not be lost andwill be made available for study giventhe new context of climate change.

The USFS Pacific NorthwestResearch Station is also initiating newlong-term field tests in collaborationwith several small- to medium-sizedforestry companies to push the limitsof moving coastal Douglas-fir prove-nances. Provenance tests and short-term seedling common garden studiesare needed for unstudied and other keyspecies. Characterizing breeding popu-lations and genotypes for adaptivetraits should help to understanddeployment options for tree improve-ment programs. Studies of reproduc-tion and establishment from seed areneeded to better understand the con-sequences of climate change on nativeforests. Continued research on geneticvariation in response to climate anddevelopment of the tools to transferknowledge of that research will con-tribute to our ability to act from a baseof knowledge about likely outcomesfrom different management options. •

Brad St.Clair is research geneticist withthe Genetics Team of the U.S. ForestService Pacific Northwest ResearchStation in Corvallis, Ore.He can bereached at 541-750-7294 or bstclair@fs.fed.us. Glenn Howe is professor in theDepartment of Forest Ecosystems andSociety at Oregon State University in

Corvallis. He can be reached at 541-737-9001 or glenn.howe@oregonstate.edu.

CitationsSt.Clair, J.B. and G.T.Howe. 2007. Geneticmaladaptation of coastal Douglas-firseedlings to future climates. Global ChangeBiology 13:1441-1454.

Wang, T.,A. Hamann, A.Yanchuck, GA.O'Neill, and S.N. Aitken. 2006. Use ofresponse functions in selecting lodgepolepine populations for future climates.Global Change Biology 12:2404-2416.

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Western Climate Initiative Focuses onRegional Cap-and-Trade System

S inceVicePresident Al

Gore went on tourwith his InconvenientTruth, there has beena flurry of ideas andproposals acrosslocal, state andnational jurisdictions as to how societyshould respond to climate change. Capand trade, carbon taxes and regulationof greenhouse gases as pollutants arejust a few of the large-scale programsbeing considered throughout theUnited States and beyond.

So why should foresters care?These policy discussions are fertileground for decision makers and thepublic to begin to understand theinherent value forests have in mitigat-ing climate change. Because of thisrecognition, there are potentialopportunities on the horizon.

With the exception of California,most states have not begun to estab-lish state-level regulation of green-house gases. At the national level,while there have been a number ofbills proposed, there has not been sig-nificant movement on climate change

policies. At press time, President -electObama supports cap and trade; how-ever, it is unclear at this point howthis issue will be prioritized in thenew administration. Most of theaction has been regional, such as thenortheast's Regional Greenhouse GasInitiative (RGGI), and in our neck ofthe woods, the Western ClimateInitiative (WCI).

WCI was formed on February 26,2007, by the governors of Washington,Oregon, California, New Mexico andArizona to establish a regional cap-and-trade system as a tool to reducethe region's greenhouse gas emis-sions. Since then, WCI has expandedto 11 members in the United Statesand Canada, as well as observers fromboth these countries and someMexican provinces.

Representatives from the executivebranches of these member states andprovinces have been meeting sinceWCI's inception to design an outlinefor a regional cap-and-trade system.The Design Recommendations for theWCI Regional Cap-and-TradeProgram were released in September2008. Since WCI has no authority ofits own to regulate greenhouse gasemissions, it is up to individual rnem-

ber states to adopt the regulatoryrequirements needed to implementthe agreement. This is an importantpoint; no matter what are agreed to inWCI negotiations, it is up to thestates, often through the legislature,to implement the proposal.

Grossly oversimplifying, cap andtrade is a regulatory program to limitthe emission of greenhouse gases, butanticipates that emissions allowancesand offsets will be traded among emit-ters to reduce the cost of meeting com-pliance obligations. Forest offsets areoften the most discussed part of cap-and-trade policy in forestry circles;however, there are many other piecesof cap-and- trade policy that can havean equal or potentially greater impactto land managers.

Greenhouse gas allowances repre-sent the right to emit one unit (the unitmeasure of greenhouse gases is reflect-ed in metric tons of carbon dioxideequivalents [mtCO2e] of greenhousegas emissions). Understanding the dis-tribution of allowances by free alloca-tion or auction is key to forecasting thepotential impact to forest landowners.Facilities covered by the cap will eitherhave to reduce emissions, acquireallowances equal to their emissions,purchase offsets to reduce emissions,or some of each. If allowances are allo-cated at no cost based on historicemissions, then the only participantsin the market are the regulated entitiesthat need the allowances to be able tocontinue to operate.

WCI has recommended that someallowances be initially auctioned,moving over time to a 100 percentauction system. This would allowgroups (e.g. financial speculators ornon-governmental organizations) topurchase allowances, which theycould then sell at a profit or retire toforce further reduction by emitters.Both have the same effect, which islimiting the supply of allowances anddriving up the cost of compliance formanufacturing facilities that needthem to stay in business. If we contin-ue to lose markets for our forest prod-ucts as a result of poor cap-and -trade

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