Does Species Diversity Limit Productivity in Natural Grassland Communities?

Authors

James B. Grace, U.S.Geological SurveyFollow
T. Michael Anderson, University of Groningen
Melinda D. Smith, Yale UniversityFollow
Eric W. Seabloom, Oregon State UniversityFollow
Sandy J. Andelman, Conservation International, Washington, DC
Gayna Meche, University of Louisiana, Lafayette, LA
Evan Weiher, University of Wisconsin, Eau Claire, WI
Larry K. Allain, U.S.GeologicalSurvey,700CajundomeBlvd.,Lafayette,LA
Heli Jutila, Hämeenlinna Region Environment Authority
Mahesh Sankaran, University of Leeds
Johannes Knops, University of Nebraska - LincolnFollow
Mark Ritchie, Syracuse University, Syracuse, NY
Michael R. Willig, University of Connecticut, Storrs, CT

Document Type

Article

Date of this Version

2007

Comments

Published in Ecology Letters, (2007) 10: 680–689. Copyright 2007. Used by permission.

Abstract

Theoretical analyses and experimental studies of synthesized assemblages indicate that under particular circumstances species diversity can enhance community productivity through niche complementarity. It remains unclear whether this process has important effects in mature natural ecosystems where competitive feedbacks and complex environmental influences affect diversity–productivity relationships. In this study, we evaluated diversity–productivity relationships while statistically controlling for environmental influences in 12 natural grassland ecosystems. Because diversity–productivity relationships are conspicuously nonlinear, we developed a nonlinear structural equation modeling (SEM) methodology to separate the effects of diversity on productivity from the effects of productivity on diversity. Meta-analysis was used to summarize the SEM findings across studies. While competitive effects were readily detected, enhancement of production by diversity was not. These results suggest that the influence of small-scale diversity on productivity in mature natural systems is a weak force, both in absolute terms and relative to the effects of other controls on productivity.