COS 119-3 - Contrasting predictions of experimental and observational studies of the response of plant communities to changing precipitation

Friday, August 7, 2009: 8:40 AM
Cinnarron, Albuquerque Convention Center
Brody S. Sandel1, Leah J. Goldstein2, Nathan Kraft3, Jordan Okie4, Michal Shuldman1, David D. Ackerly5, Elsa Cleland6 and Katharine N. Suding7, (1)Integrative Biology, UC Berkeley, Berkeley, CA, (2)Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, (3)Department of Biology, University of Maryland, College Park, MD, (4)School of Earth and Space Exploration, Arizona State University, Tempe, AZ, (5)Integrative Biology, University of California, Berkeley, CA, (6)Ecology, Behavior & Evolution Section, University of California - San Diego, CA, (7)Environmental Science, Policy & Management, University of California at Berkeley, Berkeley, CA
Background/Question/Methods
           Patterns of precipitation are likely to change significantly in the coming century, with important consequences for plant communities.  Both experimental and correlative studies offer useful predictions about how communities will respond, but little research has addressed the degree of concordance between these two approaches.  Here, we synthesize results from four experimental studies of water addition and contrast the results with a correlative analysis of community changes across a large natural gradient in precipitation.  We use plant functional traits as a basis for comparison among studies and sites, and because they provide a mechanistic basis for understanding community changes.
Results/Conclusions
            Experimental results suggested that increased precipitation should cause communities to shift towards species with smaller seed sizes and higher leaf N concentrations.  In contrast, the natural gradient analysis showed increasing seed size and decreasing leaf N with higher precipitation.  We suggest that this disagreement is due in part to the limited duration and spatial scale of experimental manipulations, which reduces the opportunities for community turnover to occur.  These results suggest that responses in natural communities to climate change are likely to be complex, and could involve transient dynamics that do not reflect the long-term shifts in community composition.
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