Wojdak Jeremy M, Mittelbach Gary G
W. K. Kellogg Biological Station, Department of Zoology, Michigan State University, 3700 E. Gull Lake Drive, Hickory Corners, Michigan 49060, USA.
Ecology. 2007 Aug;88(8):2072-83. doi: 10.1890/06-0651.1.
While the number of studies investigating the effects of species diversity on ecosystem properties continues to expand, few have explicitly examined how ecosystem functioning depends quantitatively on the degree of niche complementarity among species. We report the results of a microcosm experiment where similarity in habitat use among aquatic snail species was evaluated as a predictor of changes in community and ecosystem properties due to increasing species richness. Replicate microcosms with all possible one- and two-species combinations of a guild of six snail species were stocked with identical initial snail biomass. Microcosms with two species of snails had greater final snail biomass, lower attached algae biomass, and less total organic matter than monocultures. Snail species differed in their use of five distinct habitat types in the microcosms. Similarity in habitat use between a species pair was negatively related to the magnitude of change (e.g., deltaEF [change in ecosystem function]) in dissolved oxygen. periphyton biomass, and accrual of organic matter with a change in diversity. However, using the most stringent criterion for complementarity effects (e.g., Dmax [proportional deviation of the total polyculture yield from the highest yielding monoculture]), a relationship between species' niche similarity and changes in function with increasing species richness was only observed for dissolved oxygen. The identity of snail species present in the microcosms had strong effects on total organic matter, snail biomass, dissolved oxygen, periphyton biomass, and sedimentation rate. In this study, herbivore identity, sampling effects, and niche complementarity all appear to contribute to species richness effects on pond ecosystem properties and community structure. The analytical approach employed here may profitably be used in other systems to quantify the role of niche complementarity in species richness-ecosystem function relationships.
虽然研究物种多样性对生态系统特性影响的研究数量持续增加，但很少有研究明确考察生态系统功能如何定量地依赖于物种间生态位互补程度。我们报告了一项微观世界实验的结果，该实验将水生蜗牛物种间栖息地利用的相似性作为因物种丰富度增加而导致群落和生态系统特性变化的预测指标。用六种蜗牛组成的一个功能群的所有可能的单物种和双物种组合构建重复的微观世界，并放入相同初始蜗牛生物量。与单培养相比，含有两种蜗牛的微观世界最终蜗牛生物量更大、附着藻类生物量更低且总有机物更少。蜗牛物种在微观世界中对五种不同栖息地类型的利用存在差异。物种对之间栖息地利用的相似性与溶解氧、周丛生物量以及随着多样性变化的有机物积累的变化幅度（例如，deltaEF [生态系统功能变化]）呈负相关。然而，使用最严格的互补效应标准（例如，Dmax [混养总产量与最高产单培养产量的比例偏差]），仅在溶解氧方面观察到物种生态位相似性与随着物种丰富度增加功能变化之间的关系。微观世界中存在的蜗牛物种身份对总有机物、蜗牛生物量、溶解氧、周丛生物量和沉积速率有强烈影响。在本研究中，食草动物身份、抽样效应和生态位互补似乎都对物种丰富度对池塘生态系统特性和群落结构的影响有贡献。这里采用的分析方法可有益地用于其他系统，以量化生态位互补在物种丰富度 - 生态系统功能关系中的作用。
