Department of Evolution and Ecology, University of California, Davis, California, 95616, USA.
Department of Plant Pathology, Washington State University, Pullman, Washington, 99164, USA.
Ecology. 2021 Apr;102(4):e03290. doi: 10.1002/ecy.3290. Epub 2021 Mar 1.
Modern coexistence theory holds that stabilizing mechanisms, whereby species limit the growth of conspecifics more than that of other species, are necessary for species to coexist. Here, we used experimental and observational approaches to assess stabilizing forces in eight locally co-occurring, annual, legume species in the genus Trifolium. We experimentally measured self-limitation in the field by transplanting Trifolium species into each other's field niches while varying competition and related these patterns to the field coexistence dynamics of natural Trifolium populations. We found that Trifolium species differed in their responses to local environmental gradients and performed best in their home environments, consistent with habitat specialization and presenting a possible barrier to coexistence at fine scales. We found significant self-limitation for 5 of 42 pairwise species combinations measured experimentally with competitors absent, indicating stabilization through plant-soil feedbacks and other indirect interactions, whereas self-limitation was largely absent when neighbors were present, indicating destabilizing effects of direct plant-plant interactions. The degree of self-limitation measured in our field experiment explained year-to-year dynamics of coexistence by Trifolium species in natural communities. By assessing stabilizing forces and environmental responses in the full n-dimensional field niche, this study sheds light on the roles of habitat specialization, plant-soil feedbacks, and plant interactions in determining species coexistence at local scales.
现代共存理论认为，物种之间存在稳定机制，即同种个体的生长受到限制的程度超过其他物种，这对于物种共存是必要的。在这里，我们使用实验和观测方法来评估 8 种在一年生豆科植物 Trifolium 属中局部共存的物种的稳定力量。我们通过将 Trifolium 物种移植到彼此的田间小生境中，同时改变竞争，在野外实验中测量了自我限制，然后将这些模式与天然 Trifolium 种群的野外共存动态相关联。我们发现，Trifolium 物种对局部环境梯度的反应不同，在其原生环境中表现最佳，这与栖息地特化一致，并在细尺度上呈现出共存的可能障碍。我们发现，在没有竞争者的情况下，通过实验测量的 42 对种间组合中的 5 对存在显著的自我限制，这表明通过植物-土壤反馈和其他间接相互作用进行稳定，而当邻居存在时，自我限制则基本不存在，这表明直接的植物-植物相互作用具有不稳定性。我们在野外实验中测量的自我限制程度解释了天然群落中 Trifolium 物种的共存年际动态。通过评估稳定力量和全维田间小生境中的环境响应，本研究揭示了栖息地特化、植物-土壤反馈和植物相互作用在确定局部尺度上物种共存中的作用。
