Hector Andy, Bagchi Robert
Institute of Environmental Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
Nature. 2007 Jul 12;448(7150):188-90. doi: 10.1038/nature05947.
Biodiversity loss can affect ecosystem functions and services. Individual ecosystem functions generally show a positive asymptotic relationship with increasing biodiversity, suggesting that some species are redundant. However, ecosystems are managed and conserved for multiple functions, which may require greater biodiversity. Here we present an analysis of published data from grassland biodiversity experiments, and show that ecosystem multifunctionality does require greater numbers of species. We analysed each ecosystem function alone to identify species with desirable effects. We then calculated the number of species with positive effects for all possible combinations of functions. Our results show appreciable differences in the sets of species influencing different ecosystem functions, with average proportional overlap of about 0.2 to 0.5. Consequently, as more ecosystem processes were included in our analysis, more species were found to affect overall functioning. Specifically, for all of the analysed experiments, there was a positive saturating relationship between the number of ecosystem processes considered and the number of species influencing overall functioning. We conclude that because different species often influence different functions, studies focusing on individual processes in isolation will underestimate levels of biodiversity required to maintain multifunctional ecosystems.
生物多样性丧失会影响生态系统功能和服务。单个生态系统功能通常与生物多样性增加呈现出正渐近关系，这表明一些物种是冗余的。然而，生态系统是为多种功能而进行管理和保护的，这可能需要更多的生物多样性。在此，我们对来自草地生物多样性实验的已发表数据进行了分析，结果表明生态系统多功能性确实需要更多的物种。我们单独分析了每个生态系统功能，以确定具有理想效应的物种。然后，我们计算了所有可能功能组合中具有积极效应的物种数量。我们的结果表明，影响不同生态系统功能的物种集合存在显著差异，平均比例重叠约为0.2至0.5。因此，随着我们分析中纳入更多的生态系统过程，发现影响整体功能的物种也更多。具体而言，对于所有分析的实验，所考虑的生态系统过程数量与影响整体功能的物种数量之间存在正饱和关系。我们得出结论，由于不同物种通常影响不同功能，孤立地关注单个过程的研究将低估维持多功能生态系统所需的生物多样性水平。
