01/11/2010

New Insights Into Climate Change and Mortality in Western Forests

Summary

Drought causes significant tree mortality at the regional and global scales, but it is difficult to predict likely effects of ongoing and future climatic changes on tree mortality because the relationships between climate and mortality remain unclear. Recently published DOE-sponsored research examined relationships between tree-climate interactions and mortality of ponderosa pine in northern New Mexico. Ponderosa pine is widely distributed in North America, ranging from central Mexico to southern Canada, and may be representative of a large group of tree species. The study results indicate that trees from drier areas (i.e., growing under long-term water-limited conditions) were predisposed to mortality caused by an acute drought event, which is an unexpected result. Because increased drought severity and frequency are projected for many mid-latitude regions, it appears possible that forest mortality events will increase in the drier regions of the western United States in the coming decades.

References

McDowell NG, Allen CD, Marshall L (2010) Growth, carbon-isotope discrimination, and drought-associated mortality across a Pinus ponderosa elevational transect. Global Change Biology 16:399-415.