Slade Eleanor M, Mann Darren J, Villanueva Jerome F, Lewis Owen T
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
J Anim Ecol. 2007 Nov;76(6):1094-104. doi: 10.1111/j.1365-2656.2007.01296.x.
Much of the literature on the relationship between species richness or functional group richness and measures of ecosystem function focuses on a restricted set of ecosystem function measures and taxonomic groups. Few such studies have been carried out under realistic levels of diversity in the field, particularly in high diversity ecosystems such as tropical forests. We used exclusion experiments to study the effects of dung beetle functional group richness and composition on two interlinked and functionally important ecological processes, dung removal and secondary seed dispersal, in evergreen tropical forest in Sabah, Malaysian Borneo. Overall, both dung and seed removal increased with dung beetle functional group richness. However, levels of ecosystem functioning were idiosyncratic depending on the identity of the functional groups present, indicating an important role for functional group composition. There was no evidence for interference or competition among functional groups. We found strong evidence for overyielding and transgressive overyielding, suggesting complementarity or facilitation among functional groups. Not all mixtures showed transgressive overyielding, so that complementarity was restricted to particular functional group combinations. Beetles in a single functional group (large nocturnal tunnellers) had a disproportionate influence on measures of ecosystem function: in their absence dung removal is reduced by approximately 75%. However, a full complement of functional groups is required to maximize ecosystem functioning. This study highlights the importance of both functional group identity and species composition in determining the ecosystem consequences of extinctions or altered patterns in the relative abundance of species.
许多关于物种丰富度或功能群丰富度与生态系统功能指标之间关系的文献，都聚焦于一组有限的生态系统功能指标和分类群。在现实的野外多样性水平下，尤其是在热带森林等高多样性生态系统中，这类研究开展得很少。我们利用排除实验，研究了在马来西亚婆罗洲沙巴州的常绿热带森林中，蜣螂功能群丰富度和组成对两个相互关联且功能重要的生态过程——粪便清除和二次种子传播的影响。总体而言，粪便清除和种子清除都随着蜣螂功能群丰富度的增加而增加。然而，生态系统功能水平因现存功能群的种类而异，这表明功能群组成起着重要作用。没有证据表明功能群之间存在干扰或竞争。我们发现了超产和超量超产的有力证据，这表明功能群之间存在互补或促进作用。并非所有混合物都表现出超量超产，因此互补性仅限于特定的功能群组合。单个功能群（大型夜行掘洞者）中的甲虫对生态系统功能指标有不成比例的影响：在它们不存在的情况下，粪便清除量会减少约75%。然而，需要完整的功能群才能使生态系统功能最大化。这项研究强调了功能群种类和物种组成在确定物种灭绝或物种相对丰度模式改变对生态系统影响方面的重要性。
