Title

Climate Variability has a Stabilizing Effect on Coexistence of Prairie Grasses

Document Type

Article

Journal/Book Title/Conference

Proceedings of the National Academy of Sciences

Volume

103

Issue

34

Editor

G. David Tilman

Publisher

National Academy of Sciences

Publication Date

2006

First Page

12793

Last Page

12798

DOI

10.1073/pnas.0600599103

Abstract

How expected increases in climate variability will affect species diversity depends on the role of such variability in regulating the coexistence of competing species. Despite theory linking temporal environmental fluctuations with the maintenance of diversity, the importance of climate variability for stabilizing coexistence remains unknown because of a lack of appropriate long-term observations. Here, we analyze three decades of demographic data from a Kansas prairie to demonstrate that interannual climate variability promotes the coexistence of three common grass species. Specifically, we show that (i) the dynamics of the three species satisfy all requirements of “storage effect” theory based on recruitment variability with overlapping generations, (ii) climate variables are correlated with interannual variation in species performance, and (iii) temporal variability increases low-density growth rates, buffering these species against competitive exclusion. Given that environmental fluctuations are ubiquitous in natural systems, our results suggest that coexistence based on the storage effect may be underappreciated and could provide an important alternative to recent neutral theories of diversity. Field evidence for positive effects of variability on coexistence also emphasizes the need to consider changes in both climate means and variances when forecasting the effects of global change on species diversity.

Comments

Originally published by the National Academy of Sciences. Publisher's HTML full text and PDF available through remote link.