Successful reforestation involves planted or naturally regenerated seedlings that will be suited to the site. As the climate changes, however, genetic variants that were once an optimal choice for a specific site may also change. Current seed zones and seed transfer guidelines that specify using relatively local seed sources for reforestation assume that climates are static over the long term. We now know this assumption may no longer be valid.

Moving seed sources to match future climates requires knowledge of the response of species and populations to climate including climatic limits, as well as knowledge of future climates. The uncertainty surrounding estimates of future climates are large, so we will also need to manage for uncertainty. Increasing the genetic diversity within stands and across landscapes is one option for managing for uncertainty. Identifying highly heterogeneous microclimates that may act as refugia for species and genetic diversity may be another option for responding to climate change (Millar et al. 2007, Aitken et al. 2008).

Likely Changes

Common garden experiments of forest trees have provided ample evidence of large amounts of geographic variation in adaptive traits (e.g., timing of growth initiation and cessation, cold and drought hardiness, growth rates) with much of the variation related to gradients of temperature and moisture (Howe et al. 2003, St.Clair et al. 2005, St.Clair 2006, Aitken et al. 2008). Except at species' margins, populations are generally adapted to their local climates (Savolainen et al. 2007, Aitken et al. 2008). The use of local seed sources, however, means that the health and productivity of both planted and native forests will likely decline as climates change.

A recent study of Douglas-fir (Pseudotsuga menziesii (mirb.) Franco) in western Oregon and Washington indicated that current practices of using local sources from within current seed zones will result in a high risk of maladaptated stands by the end of the century (St.Clair and Howe 2007). They concluded that populations expected to be adapted to future climates are located 500 to 1000 m lower in elevation and 2 to 5 degrees latitude further south. A study based on an extensive set of provenance tests of lodgepole pine in British Columbia indicated that productivity would increase (up to 7 percent) given warming of about 1.5 ºC, but would substantially decline given greater warming, particularly for southern British Columbia, with some populations being extirpated (Wang et al. 2006). Productivity could be increased by as much as 14 to 36 percent, however, by moving populations to their optimal climates.

Options for Management

Activities required for adapting to the effects of climate change and maintaining genetic diversity include:

Fully characterize plant populations for genetic structure and responses to climate through new field tests in widely different environments, seedling common garden studies, and controlled-environment studies.
Relax seed transfer guidelines to allow for population movements to higher elevations and further north.
Breed for pest resistance and tolerance to climatic stresses for species in tree breeding programs.
Plant a diverse array of genotypes including mixtures of provenances.
Select broadly adapted populations and genotypes.
Consider higher planting densities to allow for natural and human selection by thinning.
Actively conduct gene conservation activities and experiment with refugia.

English Equivalents

To convert from:	To find:
Meters (m) m x 3.28	Feet
Degrees Celsius (C) 1.8 C + 32	Degrees Fahrenheit

Useful Links

Western Forests Climate Change Taskforce
http://www.cof.orst.edu/cof/fs/wfcctf/index.htm

BC Ministry of Forests – Climate Change and Seed Transfer
http://www.for.gov.bc.ca/hre/forgen/seedtransfer/seedtransfer.htm

USFS Climate Change Atlas
http://www.nrs.fs.fed.us/atlas/

References Cited

Aitken, S.N.; Yeaman, S.; Holliday, J.A.; Wang, T.; Curtis-McLane, S. 2008. Adaptation, migration or extirpation: climate change outcomes for tree populations. Evolutionary Applications. 1: 95-111.

Howe, G.T.; Aitken, S.N.; Neale, D.B.; Jermstad, K.D.; Wheeler, N.C.; Chen, T.H.H. 2003. From genotype to phenotype: unraveling the complexities of cold adaptation in forest trees. Canadian Journal of Botany. 81: 1247-1266.

Millar, C.I.; Stephenson, N.L.; Stephens, S.L. 2007. Climate change and forests of the future: managing in the face of uncertainty. Ecological Applications. 17: 2145-2151.

Savolainen, O.; Pyhäjärvi, T.; Knürr, T. 2007. Gene flow and local adaptation in trees. Annual Review of Ecology, Evolution, and Systematics 38: 595-619.

St.Clair, J.B.; Mandel, N.L.; Vance-Borland, K.W. 2005. Genecology of Douglas-fir in western Oregon and Washington. Annals of Botany. 96: 1199-1214.

St.Clair, J.B. 2006. Genetic variation in fall cold hardiness in coastal Douglas-fir in western Oregon and Washington. Canadian Journal of Botany. 84: 1110-1181.

St.Clair, J.B.; Howe, G.T. 2007. Genetic maladaptation of coastal Douglas-fir seedlings to future climates. Global Change Biology. 13: 1441-1454.

Wang, T.; Hamann, A.; Yanchuk, A.; O'Neill, G.A.; Aitken, S.N. 2006. Use of response functions in selecting lodgepole pine populations for future climates. Global Change Biology. 12: 2404-2416.

Recommended Citation

St.Clair, Brad. 2008. Genetic Resources and Climate Change. (May 23, 2008). U.S. Department of Agriculture, Forest Service, Climate Change Resource Center. http://www.fs.fed.us/ccrc/topics/genetic-resources.shtml

Genetic Resources and Climate Change

Issue

Likely Changes

Options for Management

Recommended Reading

Useful Links

References Cited

Recommended Citation