The relationship between productivity and multiple aspects of species diversity in grassland communities.
Chalcraft, David*,1, 2, 3, Wilsey, Brian4, Bowles, Christy1, Willig, Michael2, 5, 1 National Center for Ecological Analysis and Synthesis, Santa Barbara, CA2 Texas Tech University, Lubbock, TX3 East Carolina University, Greenville, NC4 Iowa State University, Ames, Iowa5 National Science Foundation, Arlington, VA
ABSTRACT- Although there has been a great deal of interest in exploring the shape of the relationship between biodiversity and productivity, most studies only have considered species richness as a measure of biodiversity. Moreover, the richness-productivity relationship depends on the spatial scale of analysis. Using data from herb-dominated plant communities from six different sites, we present the first study to examine how multiple measures of biodiversity at the level of species (species richness, evenness, dominance, rarity and Simpson's diversity index) relate to productivity at multiple spatial scales. We found that all measures of diversity were associated significantly with productivity, but the form of the relationship (e.g., linear versus hump-shaped) often differed among sites and the strength of the association was often very weak (i.e., r2 ≤ 1%). We also found little evidence for scale-dependent relationships, likely because differences in the focal scale of sampling at the sites we examined were relatively small. In cases where the association between measures of diversity and productivity were strong, the form of the relationship was different for different measures of diversity. Our results suggest that to understand the diversity-productivity relationship requires understanding how both richness and evenness relate to productivity, rather than assuming that richness-productivity relationship alone is an appropriate surrogate for the relationship with respect to all attributes of diversity.
Key words: species diversity, productivity, scale, grassland
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