Abstract: To explore the changes of non-rhizosphere， rhizosphere and rhizosheath soil bacterial communities of grassland plant under the background of climate warming and increased nitrogen deposition， high-throughput sequencing analysis of non-rhizosphere， rhizosphere and rhizosheath soil bacterial communities of the dominant grass Cleistogenes songorica （Roshev.） Ohwi was performed based on the long-term warming and nitrogen addition experimental platform in the desert steppe of Inner Mongolia. The results showed that the relative abundance of Gemmatimonadetes in the rhizosphere and rhizosheath soil was significantly increased by warming and nitrogen addition， while the relative abundance of Acidobacteria decreased. There was no significant difference on bacterial diversity in the non-rhizosphere， rhizosphere and rhizosheath soil. Compared to non-rhizosphere soil， the Shannon-Wiener index of rhizosphere and rhizosheath soil bacterial communities was decreased by 3.06% and 3.27%， respectively. Warming and nitrogen addition reduced the network complexity and stability of soil bacteria， and the network complexity and stability of soil bacteria varied at different distances from roots. In conclusion， the composition， diversity and network complexity of soil bacterial communities in the non-rhizosphere， rhizosphere and rhizosheath of Cleistogenes songorica had different responses to climate change. Future studies on the effects of climate change on soil microbes in grasslands should distinguish the differences of soil microbes at different distances from plant roots. This will lead to a deeper understanding of the interactions between plants and soil microbes and their adaptability to climate change.

Key words: Climate change, Cleistogenes songorica, Rhizosphere, Rhizosheath, Microbial network

摘要： 为探究气候变暖和氮沉降增加背景下草原植物非根际、根际和根鞘土壤细菌群落变化特征，本研究基于内蒙古荒漠草原长期增温和施氮试验平台，对优势禾草无芒隐子草[Cleistogenes songorica （Roshev.） Ohwi]非根际、根际和根鞘土壤细菌群落进行高通量测序分析。结果表明，增温+施氮处理显著增加了无芒隐子草根际及根鞘土壤中芽单胞菌门（Gemmatimonadetes）的相对丰度，降低了酸杆菌门（Acidobacteria）的相对丰度。与非根际土壤相比，根际和根鞘土壤细菌群落Shannon-Wiener指数分别降低了3.06%和3.27%，不同处理对土壤细菌群落多样性无显著影响。增温和施氮能够降低土壤细菌的网络复杂性和稳定性，距根系不同距离土壤细菌的网络复杂性和稳定性差异较大。综上，无芒隐子草非根际、根际及根鞘土壤细菌群落组成、多样性及其网络复杂性对气候变化的响应不同，未来气候变化对草地土壤微生物影响的研究应进一步区分距离植物根系不同距离土壤微生物的差异变化，这有助于更深入地理解植物与土壤微生物之间的相互作用以及它们对气候变化的适应性。

关键词: 气候变化, 无芒隐子草, 根际, 根鞘, 微生物网络