Data from: Separating sources of density-dependent and density-independent establishment limitation in invading species

1. Successful colonization by invasive species depends on both the ability to disperse seeds to a site and an ability to establish once seeds have arrived. While seed and establishment limitation are known to jointly influence colonization, decomposing establishment limitation into density-dependent and density-independent components has remained challenging. 2. Here, we couple theoretical models of recruitment with a multi-species invasion experiment conducted within a natural gradient of soil moisture and productivity to assess how variation in establishment limitation shapes outcomes for invasion. 3. Recruitment was affected by both density-dependent and density-independent sources of establishment limitation in three of four species. Soil moisture stress and productivity both increased density-independent mortality in one species, whereas density-dependent mortality increased in locations with favourable soil moisture. 4. Synthesis. Successful establishment of invading species can be limited by both density-dependent and density-independent mechanisms. In particular, the strength of density-independent limitation may depend on natural gradients in abiotic factors. The varying strengths of establishment limitation suggest that patterns of invasion are likely to be uneven both in space and in time. Understanding how intraspecific competitive constraints and density-independent limitation vary with abiotic gradients can assist with predicting when invasions are likely to occur; information that can be harnessed in the development of better methods for control.1. 入侵物种的成功定殖，既依赖其将种子扩散至目标生境的能力，也依赖种子抵达后成功建群的能力。尽管已知种子限制与建群限制（establishment limitation）共同影响定殖过程，但将建群限制拆解为密度依赖（density-dependent）与密度非依赖（density-independent）组分仍颇具挑战。 2. 本研究将幼苗补充理论模型与沿土壤湿度与生态系统生产力自然梯度开展的多物种入侵实验相耦合，以解析建群限制的变异如何影响入侵结局。 3. 四个物种中的三个，其幼苗补充过程同时受到建群限制的密度依赖与密度非依赖途径调控。其中一个物种的土壤水分胁迫与生态系统生产力均会提高其密度非依赖死亡率，而密度依赖死亡率则在土壤湿度适宜的生境中升高。 4. 【综合与结论】入侵物种的成功建群可同时受密度依赖与密度非依赖机制的限制。具体而言，密度非依赖限制的强度可能取决于非生物因子的自然梯度。建群限制强度的异质性表明，入侵格局在空间与时间维度上均可能呈现非均匀性。阐明种内竞争约束与密度非依赖限制如何随非生物梯度发生变异，有助于预测入侵事件的发生时机，相关信息可用于开发更高效的入侵防控手段。