Size asymmetry of resource competition and the structure of plant communities

作者：Niv DeMalach, Eli Zaady, Jacob Weiner, Ronen Kadmon · 发表于：Journal of Ecology · 年份：2016 · DOI：10.1111/1365-2745.12557 · 被引用次数：170 · 研究领域：Ecology and Vegetation Dynamics Studies、Plant and animal studies、Ecosystem dynamics and resilience

Summary Plant communities show two general responses to gradients of soil resources: a decrease in species richness at high levels of resource availability and an associated shift in species composition from small and slow‐growing species to large and fast‐growing species. Models attempting to explain these responses have usually focused on a single pattern and provided contradicting predictions concerning the underlying mechanisms. We use an extension of Tilman's resource competition model to investigate the hypothesis that both patterns may originate from the size‐asymmetric nature of light exploitation by competing plants. The only mechanism producing changes in species richness and species composition in our model is mortality due to competition. Under the framework of the model, asymmetric light exploitation is a necessary and sufficient condition to obtain the empirically observed responses of species richness and species composition to soil resource gradients. This theoretical result is robust to relaxing the simplifying assumptions of the model. Our model shows that the traits enhancing competitive superiority depend on the mode of resource exploitation: under symmetric exploitation, competitive superiority is achieved by tolerance of low resource levels, while under asymmetric exploitation, it is achieved by the ability to grow fast and attain a large size. This result indicates that a long‐standing debate concerning the traits that enhance competitive superiority in...