Impacts of Climate Extremes on Bio-Communities

PNAS | March 4, 2008 | vol. 105 | no. 9 | 3410-3415


Impact of an extreme climatic event on community assembly
Katherine M. Thibault, and James H. Brown

Department of Biology, University of New Mexico,
Albuquerque, NM 87131; and Department of Biology,
Furman University, Greenville, SC 29613

Extreme climatic events are predicted to increase
in frequency and magnitude, but their ecological
impacts are poorly understood. Such events are
large, infrequent, stochastic perturbations that
can change the outcome of entrained ecological
processes. Here we show how an extreme flood
event affected a desert rodent community that has
been monitored for 30 years. The flood (i) caused
catastrophic, species-specific mortality; (ii)
eliminated the incumbency advantage of previously
dominant species; (iii) reset long-term
population and community trends; (iv) interacted
with competitive and metapopulation dynamics; and
(v) resulted in rapid, wholesale reorganization
of the community. This and a previous extreme
rainfall event were punctuational
perturbations-they caused large, rapid
population- and community-level changes that were
superimposed on a background of more gradual
trends driven by climate and vegetation change.
Captured by chance through long-term monitoring,
the impacts of such large, infrequent events
provide unique insights into the processes that
structure ecological communities.

desert rodents | incumbency advantage | punctuational dynamics

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