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）是分布最广、最为普遍的土壤动物类群，在维持土壤健康与保障农业生产力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构建（community assembly）的内在机制，尤其是这些机制随不同空间尺度（spatial scales）的变化规律，目前仍未得到充分阐释。本研究在跨度达4138公里的地理范围内，覆盖农业生态系统的多个空间尺度，对土壤线虫的群落构建过程开展了系统性探究。研究结果揭示了土壤线虫群落构建存在显著的尺度依赖模式：随着空间尺度的扩大，扩散限制（dispersal limitation）对群落构建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构建过程变异的关键驱动因子。本研究为理解土壤线虫的空间动态及其尺度依赖的群落构建机制提供了全新视角，对预测未来环境变化下其生态系统功能的演变具有重要指导意义。