Climatic variability and coexistence in a Kansas grassland.
Adler, Peter*,1, Hille Ris Lambers, Janneke1, Levine, Jonathan1, 1 University of California, Santa Barbara, CA, USA
ABSTRACT- The probability of extreme storms and droughts is forecast to increase under climate change. In ecosystems where climatic variability plays a role in maintaining species diversity, these changes may have important implications. Fortunately, theoretical work on the storage effect provides tools for evaluating this possibility. We used a spatially-explicit, 36-year time series from permanent plots in western Kansas to ask whether climate variability stabilized coexistence of dominant grass species in the past. We linked storage effect theory with these data using a Bayesian hierarchical modeling approach that allowed us to simulate population growth rates under a variety of conditions. Our analyses showed that all three of the species we examined, Bouteloua curtipendula, Bouteloua hirsuta, and Schyzachyrium scoparium, had long-lived life stages and performed best in different years, indicating the presence of the first two ingredients of the storage effect. For two of the three species, the effect of competition was significantly more severe during the most favorable years, the third condition necessary for climatic variability to have a stabilizing effect on coexistence. These results represent a first step towards understanding the effects of future changes in climatic variability on local species diversity.
Key words: storage effect, species diversity, Bayesian, modeling
All materials copyright The Ecological Society of America (ESA), and may not be used without written permission.