Ecology and Evolutionary Biology Program, Oklahoma Biological Survey and Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
Ecology. 2011 May;92(5):1013-9. doi: 10.1890/10-0219.1.
Several decades of research have shown that biodiversity affects ecosystem processes associated with resource capture and the production of biomass within trophic levels. Although there are good reasons to expect that biodiversity influences non-trophic ecosystem processes, such as the physical creation or modification of habitat, studies investigating the role of biodiversity on physical processes are scarce. Here we report the results of a study using artificial streams to test the influence of freshwater mussel biodiversity on gravel erosion during high flows while manipulating mussel abundance. Mussel species vary in traits that should influence their effects on erosion, such as size, shell morphology, and burrowing behavior. We found that mussel species richness was associated with an increase in erosion at both low and high densities. Planned contrasts showed that the erosion observed in species mixtures was purely additive at low density, indicating that erosion in a species polyculture could routinely be predicted by the performance of monocultures. However, at high density certain combinations of species showed nonadditive effects on erosion, suggesting that organism abundance can fundamentally alter biodiversity effects. Although this may have been a result of altered species interactions at high density, our study design cannot confirm this.
几十年来的研究表明，生物多样性会影响与资源捕获和营养级内生物质生产相关的生态系统过程。尽管有充分的理由预期生物多样性会影响非营养生态系统过程，例如生境的物理创造或改造，但研究生物多样性对物理过程的作用的研究却很少。在这里，我们报告了一项使用人工溪流的研究结果，该研究旨在测试在高流量期间，淡水贻贝生物多样性对砾石侵蚀的影响，同时操纵贻贝的丰度。贻贝物种在大小、壳形态和挖掘行为等特征上存在差异，这些特征应该会影响它们对侵蚀的影响。我们发现，在低密度和高密度时，贻贝物种丰富度与侵蚀的增加有关。计划的对比表明，在低密度时，观察到的物种混合物中的侵蚀纯粹是加性的，这表明在物种混养中，侵蚀通常可以通过单培养物的性能来预测。然而，在高密度时，某些物种组合对侵蚀表现出非加性效应，这表明生物量的增加可以从根本上改变生物多样性的影响。尽管这可能是由于高密度下物种相互作用的改变，但我们的研究设计无法证实这一点。
