Climate Change and Oaks

Oak Woodlands
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Climate Change

Now that is a topic for you! How can scientists predict what effect climate change will have on oaks?
Scientists already know a great deal about factors in the environment that affect the distribution of plants. One of the most important variables in the environment is both average night time temperatures, and the probability of night time lows that exceed the tolerance of a plant. For instance, if you had a jade plant growing outdoors where it generally did not freeze at night, it could thrive and grow. But just one night of a freeze to near 20 deg. (F) and that plant is dead. To generalize from your tomato garden, there are some plants that can tolerate regular freezing, and some that cannot. And, there are all shades of tolerance of night temperatures.

If you garden, you may know about the "Climate Zones" in the Sunset Western Garden Book, pretty much the book of reference for landscape folks. These climate zones give you a good idea of the kind of plants that grow and thrive in each zone. The concern that scientists have is that the boundaries of those zones can change and the range of habitats a species can occupy changes (1,2).

Using several environmental variables, including night temperatures being recorded in California, Loarie at al (3) found that the range of many plants will probably change dramatically in the next 50 years. Given that an oak can live 800 years, what are the chances that it will be planted in a place that eventually won't support it? Well. Who knows? One of the senior authors (David Ackerly, pers. com. 2009) suggests that the data could be interpreted such that the oak woodlands of Monterey County would largely appear like the Joshua Tree forests of Riverside County in the next 80 years.

Climate change, and its affect on the landscape appear to be important and many conservation biologists are concerned that the present distribution of plants will be dramatically changed (5-9). There is hope, however (10).

1. Parmesan C (1996) Climate and species’ range. Nature 382: 765–766.
2. Schneider SH, Root TL (2001) Wildlife responses to climate change. Washington, D.C.: Island Press.
3. Loarie, S. R., B. E. Carter, K. Hayhoe, S. McMahon, R. Moe, C. A. Knight, and D. D. Ackerly. 2008. Climate change and the future of California's endemic flora. PLoS ONE 3:e2502.

4. ARB. 2008. Air Resources Board: Climate Change and Forestry in California. Air Resources Board, State of California. Oct 1, 2008.

5. Harris, J. A., R. J. Hobbs, E. Higgs, and J. Aronson. 2006. Ecological restoration and global climate change. Restoration Ecology 14:170-176.

6. Kueppers, L. M., M. A. Snyder, L. C. Sloan, E. S. Zavaleta, and B. Fulfrost. 2005. Modeled regional climate change and California enaemic oak ranges. Proceedings of the National Academy of Sciences of the United States of America 102:16281-16286.

7. Lobell, D. B., C. B. Field, K. N. Cahill, and C. Bonfils. 2006. Impacts of future climate change on California perennial crop yields: model projections with climate and crop undertainties. Agriculture and Forest Meteorology 141:208-218.

8. Pachauri, R. K. and A. Reisinger, editors. 2007. Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). IPCC, Geneva, Switzerland.

9. Thorne, J. H., B. J. Morgan, and J. A. Kennedy. 2008. Vegetation change over sixty years in the central Sierra Nevada, California, USA. Madrono 55:223-227.

10. Smith, H. J., J. Fahrenkamp-Uppenbrink, and R. Coontx. 2009. Clearing the Air: Introduction to Special Section: Carbon Capture and Sequestration. Science 325:1641.