Mathematical Biology Seminar|
Department of Forest, Range, and Wildlife Sciences
Utah State University
Wednesday, Feb 15, 2006
"Does climate variability stabilize plant species
coexistence? A test of current theory with really old data"
Theoretical ecologists often complain that empiricists ignore their work,
and instead run around measuring all the wrong things. This seminar
provides a rare opportunity to see what actually happens when a field
ecologist with poor math skills makes a determined attempt to test theory.
The theory in question involves the "storage effect," which describes how
temporal environmental fluctiations can stabilize the coexistence of
competing species. This coexistence mechanism is relevant to questions
about how climate change will impact species diversity, since climate
variability is forecast to increase in the future. I test the theory by
analyzing a unique demographic dataset collected in Kansas prairie from
1937-1972 with a hierarchical Bayesian model. The results show that i) the
dynamics the three perennial grass species satisfy all requirements of
storage effect theory, ii) climate variables are correlated with
interannual variation in performance of these three species, and iii)
temporal variability increases low density growth rates, buffering these
species against competitive exclusion. I discuss implications of these
results for recent neutral theories of diversity, and also for predicting
the effects of global change on species diversity.