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Recent Environmental Change in the
Malpai Borderlands
James H. Brown, Department of Biology, University of New Mexico,
Albuquerque, NM
T
wenty-one years of ecological experimentation and monitoring at my study
site near Portal provide interesting perspectives on long-term ecological dynamics. We have found the following:
l. The climate has changed. Winter precipitation has been significantly greater
than the century-long average.
2. The vegetation has changed. Woody shrubs with C3 photosynthesis have
increased several fold, and there has been a corresponding decrease in
grasses with C4 photosynthesis.
3. Species composition of small mammals has changed dramatically. Previously
dominant species have gone locally extinct, while previously unrecorded
species have colonized.
4. Total abundance, biomass, energy use, and species diversity have remained
virtually constant.
These observations provide valuable insights into the role of compensatory
population dynamics, including colonization and extinction processes, in maintaining relative constant species diversity and ecosystem processes in the face of
substantial environmental change. They also suggest that it will often be difficult
to predict ecological consequences of environmental change for purposes of management and policy.
USDA Forest Service Proceedings RMRS-P-10. 1999.
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