Positive biodiversity–productivity relationship due to increased plant density

作者：Elisabeth Marquard, Alexandra Weigelt, Christiane Roscher, Marlén Gubsch, Annett Lipowsky, BERNHARD H. SCHMID · 发表于：Journal of Ecology · 年份：2009 · DOI：10.1111/j.1365-2745.2009.01521.x · 被引用次数：191 · 研究领域：Ecology and Vegetation Dynamics Studies、Plant and animal studies、Pasture and Agricultural Systems

1 Positive effects of biodiversity on plant productivity may result from diversity-induced changes in the size or density of individual plants, yet these two possibilities have never been tested at the same time in a biodiversity experiment with a large species pool. Here, we distinguish between size effects and density effects on plant productivity, using data from 198 experimental grassland communities that contained 1–16 species. Plant modules such as tillers or rosettes were defined as relevant units, being equivalent to plant individuals in the majority of species. 2 In agreement with previous studies, we found positive effects of species richness on above-ground productivity. We show that this positive biodiversity effect resulted from diversity-induced increases in module density rather than from increases in module size. In contrast, variation in productivity within diversity levels was related to module size rather than module density. 3 The size–density relationships varied among plant functional groups and among species but their average response to increasing species richness paralleled the pattern observed at the level of the entire plant communities: species richness had a positive effect on above-ground species biomass and species module density but not on species module size. Twenty-four out of 26 overyielding species had denser populations and 25 out of 28 underyielding species had smaller modules in mixtures than in monocultures. 4 Synthesis. In grasslands, ...