Tree Mortality and Insights from a Decade of Climate Change Research


Ongoing global climatic change is expected to result in longer and more frequent droughts. Recent drought in the western United States has been associated with widespread mortality of pine trees, but because the mechanism of action has been unclear it has been impossible to realistically account for such mortality in global climate models. Now, after 10 years of DOE-sponsored research, it has been determined that long-term drought reduces photosynthesis (carbon assimilation) in pine trees to such an extent that they become “carbon starved.” As a result, they are not able to ward off other stresses, such as attack by bark beetles. This new insight into the mechanism of action of drought on tree health will allow global climate models to appropriately account for potential ecological effects of climatic change.


Breshears, D.B., Myers O.B., Meyer, C.W., Barnes, F.J., Zou, C.B., Allen, C.D., McDowell, N.G., Pockman, W.T. (2009) Tree die-off in response to global change-type drought: mortality insights from a decade of plant water potential measurements. Frontiers in Ecology and the Environment 7:185-189.