Does natural variation in diversity affect biotic resistance?

1. Theories linking diversity to ecosystem function have been challenged by the widespread observation of more exotic species in more diverse native communities. Few studies have addressed the key underlying process by dissecting how community diversity is shaped by the same environmental gradients that determine biotic and abiotic resistance to new invaders. 2. In grasslands on highly heterogeneous soils, we used addition of a recent invader, competitor removal, and structural equation modelling (SEM) to analyse soil influences on community diversity, biotic and abiotic resistance, and invader success. 3. Biotic resistance, measured by reduction in invader success in the presence of the resident community, was negatively correlated with species richness and functional diversity. However, in the multivariate SEM framework, biotic resistance was independent of all forms of diversity, and was positively affected by soil fertility via community biomass. Abiotic resistance, measured by inva...1. 将生物多样性与生态系统功能相关联的经典理论，因“物种更丰富的本地群落中往往共存更多外来物种”这一普遍观测结果而受到挑战。目前鲜有研究通过解析核心潜在过程来回应这一争议：即群落多样性如何由同一环境梯度所塑造，而该环境梯度同时决定了群落对新入侵者的生物抗性与非生物抗性。2. 在高度异质化土壤的草原生态系统中，本研究通过引入近期入侵物种、移除本土竞争者，并结合结构方程模型（structural equation modelling, SEM），分析了土壤因子对群落多样性、生物与非生物抗性以及入侵者入侵成功率的影响。3. 以本地群落存在时入侵者入侵成功率的下降幅度为衡量指标的生物抗性，与物种丰富度和功能多样性呈负相关关系。然而在多变量结构方程模型框架下，生物抗性与各类多样性均无关联，土壤肥力通过提升群落生物量，对其产生正向影响。非生物抗性，其衡量指标为入侵……