Body size is an important life-history trait that affects organism niche occupancy and ecological interactions. However, it is still unclear to what extent the assembly process of organisms with different body sizes affects soil biogeochemical cycling processes at the aggregate level. Here, we examined the diversity and community assembly of soil microorganisms (bacteria, fungi, and protists) and microfauna (nematodes) with varying body sizes. The microbial functional potential associated with carbon, nitrogen, phosphorus, and sulfur metabolism within three soil aggregate sizes (large macroaggregates, > 2 mm; small macroaggregates, 0.25−2 mm; and microaggregates, < 0.25 mm) were determined by metagenomics. We found that the smallest microbes (bacteria) had higher α-diversity and lower β-diversity and were mostly structured by stochastic processes, while all larger organisms (fungi, protists, and nematodes) had lower α-diversity and were relatively more influenced by deterministic processes. Structural equation modeling indicated that the microbial functional potential associated with carbon, nitrogen, phosphorus, and sulfur metabolism was mainly influenced by the bacterial and protist diversity in microaggregates. In contrast, the microbial functional potential was primarily mediated by the assembly processes of four organism groups, especially the nematode community in macroaggregates. This study reveals the important roles of soil organisms with different body sizes in the functional potential related to nutrient cycling, and provides new insights into the ecological processes structuring the diversity and community assembly of organisms of different body sizes at the soil aggregate level, with implications for soil nutrient cycling dynamics.

中文翻译：

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体型通过土壤团聚体的多样性和群落组装来调节土壤生物的功能潜力

体型是一个重要的生活史特征，影响生物体生态位占用和生态相互作用。然而，目前尚不清楚不同体型生物的组装过程在总体水平上对土壤生物地球化学循环过程的影响程度如何。在这里，我们研究了不同体型的土壤微生物（细菌、真菌和原生生物）和微型动物（线虫）的多样性和群落组装。通过宏基因组学确定了三种土壤团聚体尺寸（大团聚体，> 2 mm；小团聚体，0.25−2 mm；微团聚体，< 0.25 mm）内与碳、氮、磷和硫代谢相关的微生物功能潜力。我们发现最小的微生物（细菌）具有较高的 α 多样性和较低的 β 多样性，并且主要由随机过程构成，而所有较大的生物体（真菌、原生生物和线虫）具有较低的 α 多样性，并且相对更多地受随机过程的影响。确定性过程。结构方程模型表明，与碳、氮、磷、硫代谢相关的微生物功能潜力主要受微团聚体中细菌和原生生物多样性的影响。相反，微生物功能潜力主要由四个生物群的组装过程介导，特别是大团聚体中的线虫群落。这项研究揭示了不同体型的土壤生物在与养分循环相关的功能潜力中的重要作用，并为在土壤总量水平上构建不同体型的生物多样性和群落组装的生态过程提供了新的见解，具有重要意义土壤养分循环动态。