Local Factors Determine Plant Community Structure on Closely Neighbored Islands

Jianbo Lu,Lin Yu,Lin Jiang,Que Sun,Andrew Hector

doi:10.1371/journal.pone.0019762

Abstract

Despite the recent popularity of the metacommunity concept, ecologists have not evaluated the applicability of different metacommunity frameworks to insular organisms. We surveyed 50 closely spaced islands in the Thousand-Island Lake of China to examine the role of local (environmental) and regional (dispersal) factors in structuring woody plant assemblages (tree and shrub species) on these islands. By partitioning the variation in plant community structure into local and regional causes, we showed that local environmental conditions, specifically island morphometric characteristics, accounted for the majority of the variation in plant community structure among the studied islands. Spatial variables, representing the potential importance of species dispersal, explained little variation. We conclude that one metacommunity framework–species sorting–best characterizes these plant communities. This result reinforces the idea that the traditional approach of emphasizing the local perspective when studying ecological communities continues to hold its value.

Highlights

Understanding mechanisms regulating the structure of ecological communities is a central goal of community ecology
The prevailing opinion among ecologists is that species composition and abundance in a locality largely reflect species responses to local environmental conditions and the outcomes of species interactions, which are themselves influenced by local environmental conditions
We identified the operating metacommunity framework by partitioning the variation [34] in plant community structure among the islands, with mass effects indicated by a significant spatial signature of the communities, independent of the variation in environmental conditions among the islands, as well as a significant effect of local environmental conditions on the communities, independent of the spatial structure of the communities [17]

Summary

Introduction

Understanding mechanisms regulating the structure of ecological communities is a central goal of community ecology. The prevailing opinion among ecologists is that species composition and abundance in a locality largely reflect species responses to local environmental conditions and the outcomes of species interactions, which are themselves influenced by local environmental conditions This local perspective, which has its roots in the classic niche theory [1,2,3,4], suggests that among-habitat differences in community structure are largely deterministic outcomes of differences in environmental conditions among habitats. This regional perspective is captured in neutral biodiversity models that assume functional equivalency among species across all habitats [8,9,10] These neutral models suggest that among-habitat differences in community structure may arise from limited dispersal preventing species from reaching every habitat

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Conclusion