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Drought & Die-off
Dr. Dave Breshears, in the School of Natural Resources and the Environment, documented massive pinyon pine die-off due to extended drought. He and his colleagues had collected a wealth of data on the woodlands for more than a decade before the massive die-off.
At study sites in Arizona, Colorado, New Mexico and Utah, Dr. Breshears' team found that from 40 to 80 percent of the pinyon trees (Pinus edulis) died between 2002 and 2003, including even in some of best locations for pinyons. The researchers confirmed this massive die-off through both aerial surveys and analysis of satellite images .
Another intense drought in the 1950's did not cause similar die-offs. Why did it happen this time? To find the answer, Breshears' team compared the two droughts. They concluded that higher temperatures in the recent drought contributed to the die-off. Hotter temperatures coupled with drought are one of the kinds of events that are predicted by global climate change models. Dr. Breshears' research findings suggest that big, abrupt changes in ecosystems may result from global climate change.
Dr. Breshears continues to look at ecosystems that span a continuum from grassland to forest, studying the ways in which carbon and water cycles interact with large scale climatic variation. Ultimately, this research will help lead to the development of tools for managing natural resources in the face of potentially abrupt environmental change.
Craig D. Allen, U.S.G.S.
Neil S. Cobb, Northern Arizona University
Paul M. Rich, Creekside Center for Earth Observation
Drought Impacts on Regional Ecosystems Network (DIREnet)
Los Alamos National Laboratory (LANL)
National Science Foundation
U.S. Forest Service
U.S. Geological Survey
National Institutes of Health
Allen, C. D., and D. D. Breshears. 1998. Drought-induced shift of a forest-woodland ecotone: rapid landscape response to climate variation. Proceedings of the National Academy of Sciences of the United States of America 95:14839-14842.
Whicker, J.J, D.D. Breshears , P.T. Wasiolek , T.B. Kirchner, R.A. Tavani , D.A. Schoep , J.C. Rodgers. 2002. Temporal and spatial variation of episodic wind erosion in unburned and burned semiarid shrubland. Journal of Environmental Quality 31: 599-612.