Abstract: To investigate the effects of soil depth on microbial diversity across different plant communities， this study examined the physicochemical properties and microbial diversity of soil at three depths （0-20 cm， 20-40 cm， and 40-60 cm） under five representative plant communities in the Qaidam Haloxylon Ecosystem Reserve， including Haloxylon ammodendron，Nitraria sibirica， Kalidium foliatum， Tamarix hohenackeri， and Calligonum mongolicum. The findings revealed that different plant communities significantly altered soil physicochemical properties and microbial composition， whereas the influence of soil depth on these properties and microbial diversity was markedly less pronounced. Among the soil properties affecting microbial communities， total salinity emerged as the most critical factor.The T. ramosissima community had the highest levels of total salinity， organic matter， and total nitrogen. These led to a significant increase in the abundance of Bacteroidota and Basidiomycota， while reducing the abundance of Ascomycota. Despite changes in microbial composition driven by plant communities， the dominant microbial phyla in the soil remained consistent. The predominant bacterial phyla were Actinobacteriota and Proteobacteria， while Ascomycota and Basidiomycota dominated the fungal communities. Functional profiling revealed that the dominant bacterial groups were chemoheterotrophs and aerobic chemoheterotrophs. These findings elucidated the interplay between plant communities and soil depth in shaping soil physicochemical properties and microbial diversity. They enhance our understanding of the mechanisms underlying the formation and assembly of soil microbial communities in the Qaidam Desert ecosystem.

Key words: Soil physicochemical properties, Microbial diversity, Soil depth, Dominant microbial phyla

摘要： 为探究不同植物群落中土层深度对微生物多样性的影响。本研究对柴达木梭梭林保护区内梭梭、西伯利亚白刺、细枝盐爪爪、多花柽柳、蒙古沙拐枣5种典型植物群落下的0~20 cm，20~40 cm，40~60 cm土壤理化性质和微生物多样性进行了测定。不同植物群落显著改变了土壤理化性质和微生物组成。而土层深度对于土壤理化性质和微生物多样性影响远低于不同植物群落的效应。全盐含量是影响微生物群落的最重要因素。柽柳群落中全盐、有机质、全氮等含量最高，导致了拟杆菌门（Bacteroidota）、担子菌门（Basidiomycota）丰度的显著提高，降低了子囊菌门（Ascomycota）丰度。不同植物群落中土壤微生物的组成不同，但主要的优势菌群没有发生改变。优势细菌门为放线菌门、变形菌门，优势真菌门为子囊菌门、担子菌门。优势细菌功能类群为化能异养和好氧化能异养菌。本研究揭示了植物群落和土壤深度对土壤理化性质和微生物群落多样性的关系，有助于深入了解柴达木荒漠生态系统中土壤微生物群落多样性形成和构建机制。

关键词: 土壤理化性质, 微生物多样性, 土壤深度, 优势菌群