Scale-dependent dispersal limitation in soil nematode community assembly across agricultural ecosystems

Soil nematodes, which are the most prevalent and widespread group of soil fauna, play a crucial role in maintaining soil health and supporting agricultural productivity. Despite their importance, the mechanisms underlying the assembly of soil nematode communities in agricultural ecosystems, particularly how these mechanisms vary across different spatial scales, remain poorly understood. In this study, we examined the community assembly processes of soil nematodes across a geographical span of 4,138 km, covering multiple spatial scales within agricultural ecosystems. Our findings highlight a distinct scale-dependent pattern in the assembly of soil nematode communities, with dispersal limitation becoming increasingly dominant as spatial scale expands. Additionally, we identified soil nitrogen, total phosphorus, and precipitation as key drivers influencing the variability in these assembly processes across spatial scales. This study provides novel insights into the spatial dynamics and scale-dependent community assembly of soil nematodes, with important implications for predicting changes in their ecosystem functions in response to future environmental changes.土壤线虫（soil nematodes）是分布最为广泛、最具普遍性的土壤动物类群，在维系土壤健康与支撑农业生产效能方面发挥着至关重要的作用。尽管其生态重要性不言而喻，但农业生态系统中土壤线虫群落的组装机制，尤其是这些机制随不同空间尺度的变化规律，目前仍缺乏深入的认知。本研究覆盖4138公里的地理跨度，涵盖农业生态系统内的多个空间尺度，对土壤线虫的群落组装过程开展了系统性考察。研究结果揭示了土壤线虫群落组装存在显著的尺度依赖模式：随着空间尺度的扩大，扩散限制的调控作用逐渐占据主导地位。此外，本研究明确了土壤氮、总磷与降水量是调控不同空间尺度下群落组装过程差异的关键驱动因子。本研究为土壤线虫的空间动态及尺度依赖型群落组装机制提供了全新的研究视角，同时对预测未来环境变化下其生态系统功能的演变具有重要的指导意义。