Nature 441, 629-632 (1 June 2006) | doi:10.1038/nature04742; Received 20 December 2005; Accepted 23 March 2006

There is a Brief Communications Arising (29 March 2007) associated with this document.

Biodiversity and ecosystem stability in a decade-long grassland experiment

David Tilman1, Peter B. Reich2 & Johannes M. H. Knops3

  1. Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, St Paul, Minnesota 55108, USA
  2. Department of Forest Resources, University of Minnesota, 1530 North Cleveland Avenue, St Paul, Minnesota 55108, USA
  3. School of Biological Sciences, University of Nebraska, 348 Manter Hall, Lincoln, Nebraska 68588-0118, USA

Correspondence to: David Tilman1 Correspondence and requests for materials should be addressed to D.T. (Email: tilman@umn.edu).

Human-driven ecosystem simplification has highlighted questions about how the number of species in an ecosystem influences its functioning. Although biodiversity is now known to affect ecosystem productivity1, 2, 3, 4, 5, 6, its effects on stability are debated6, 7, 8, 9, 10, 11, 12, 13. Here we present a long-term experimental field test of the diversity–stability hypothesis. During a decade of data collection in an experiment that directly controlled the number of perennial prairie species4, growing-season climate varied considerably, causing year-to-year variation in abundances of plant species and in ecosystem productivity. We found that greater numbers of plant species led to greater temporal stability of ecosystem annual aboveground plant production. In particular, the decadal temporal stability of the ecosystem, whether measured with intervals of two, five or ten years, was significantly greater at higher plant diversity and tended to increase as plots matured. Ecosystem stability was also positively dependent on root mass, which is a measure of perenniating biomass. Temporal stability of the ecosystem increased with diversity, despite a lower temporal stability of individual species, because of both portfolio (statistical averaging) and overyielding effects. However, we found no evidence of a covariance effect. Our results indicate that the reliable, efficient and sustainable supply of some foods (for example, livestock fodder), biofuels and ecosystem services can be enhanced by the use of biodiversity.


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