Tilman David, Reich Peter B, Knops Johannes M H
Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, St Paul, Minnesota 55108, USA.
Nature. 2006 Jun 1;441(7093):629-32. doi: 10.1038/nature04742.
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 productivity, its effects on stability are debated. 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 species, 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.
人类驱动的生态系统简化凸显了关于生态系统中物种数量如何影响其功能的问题。尽管现在已知生物多样性会影响生态系统生产力，但其对稳定性的影响仍存在争议。在此，我们展示了一项关于多样性 - 稳定性假说的长期实验性田间测试。在一项直接控制多年生草原物种数量的实验中，经过十年的数据收集，生长季节的气候差异很大，导致植物物种丰度和生态系统生产力逐年变化。我们发现，植物物种数量越多，生态系统地上部分年植物产量的时间稳定性就越高。特别是，无论以两年、五年还是十年为间隔进行测量，生态系统的十年时间稳定性在较高植物多样性水平下显著更高，并且随着样地成熟而趋于增加。生态系统稳定性还正向依赖于根质量，根质量是多年生生物量的一个衡量指标。尽管单个物种的时间稳定性较低，但由于组合（统计平均）和超产效应，生态系统的时间稳定性随多样性增加。然而，我们没有发现协方差效应的证据。我们的结果表明，利用生物多样性可以增强某些食物（例如，牲畜饲料）、生物燃料和生态系统服务的可靠、高效和可持续供应。
