Plant–soil feedbacks promote negative frequency dependence in the coexistence of two aridland grasses

Understanding the mechanisms of species coexistence is key to predicting patterns of species diversity. Historically, the ecological paradigm has been that species coexist by partitioning resources: as a species increases in abundance, self-limitation kicks in, because species-specific resources decline. However, determining coexistence mechanisms has been a particular puzzle for sedentary organisms with high overlap in their resource requirements, such as plants. Recent evidence suggests that plant-associated microbes could generate the stabilizing self-limitation (negative frequency dependence) that is required for species coexistence. Here, we test the key assumption that plant–microbe feedbacks cause such self-limitation. We used competition experiments and modelling to evaluate how two common groups of soil microbes (rhizospheric microbes and biological soil crusts) influenced the self-limitation of two competing desert grass species. Negative feedbacks between the dominant plant c...阐明物种共存机制是预测物种多样性格局的核心所在。长期以来，生态学主流范式认为物种通过资源划分实现共存：当某一物种的多度上升时，其种特异性资源因消耗减少，进而触发自身限制效应。然而，对于资源需求重叠度极高的固着生物（如植物）而言，解析其共存机制始终是一大难题。近期研究证据表明，植物关联微生物可产生维持物种共存所需的稳定性自身限制效应（负频率依赖，negative frequency dependence）。本研究针对“植物-微生物反馈可引发此类自身限制效应”这一核心假设展开验证，通过竞争实验与模型模拟，评估两类常见土壤微生物——根际微生物（rhizospheric microbes）与生物土壤结皮（biological soil crusts）——对两种竞争荒漠草本植物自身限制效应的影响。优势植物间的负反馈...