高寒草原灌丛化对土壤碳库和土壤微生物群落结构的影响  

Effects of Shrub Encroachment on Soil Carbon Pool and Soil Microbial Community Structure in Alpine Grassland

作　　者：邓增卓玛 马文明[1] 马祥丽 母先润 TENZING Droma;MA Wenming;MA Xiangli;MU Xianrun(College of Grassland Resources,Southwest Minzu University,Chendu 610041,China)

机构地区：[1]西南民族大学草地资源学院,成都610041

出　　处：《土壤学报》2025年第1期261-272,共12页Acta Pedologica Sinica

基　　金：高寒湿地生态保护研究创新团队项目(2024CXTD10);西南民族大学“双一流”项目(CX2023030);西南民族大学研究生创新型科研项目(CX2021SZ27)资助。

摘　　要：在气候变化和过度放牧等的影响下,全球草地灌丛化现象愈发严重。然而,高寒草地土壤微生物群落对灌丛化的响应尚不清楚。以青藏高原东缘3种典型灌丛化草地(高山绣线菊Spiraea alpina、金露梅Potentilla fruticosa、小叶锦鸡儿Caragana microphylla)和无灌丛生长的草地为研究对象,通过分析植物群落结构、土壤碳组分、细菌群落结构及菌群互作关系,拟揭示高寒草原灌丛化对土壤微生物群落结构和土壤碳库的影响。基于16S rRNA基因测序技术研究土壤细菌群落及其共生特征,并结合傅立叶变换红外光谱(FTIR)分析了土壤有机碳(SOC)化学组成。结果表明,灌丛化草地(小叶锦鸡儿和金露梅)地上植物群落组成均发生显著改变(P<0.01),而地上植物群落多样性和丰富度无显著变化(P>0.05)。三种灌丛样地地上生物量均显著高于草地(P<0.05),而地下生物量则无显著差异(P>0.05)。灌丛化对SOC和全氮(TN)含量无显著影响,但减小了表层与深层SOC含量的差异,具体表现为草地表层土壤SOC显著高于其深层(P<0.05),但三种灌丛样地无此趋势。三种灌丛和草地表层和深层土壤SOC组分均以芳香族为主(除小叶锦鸡儿深层土壤外),灌丛和草地样地间芳香族含量无显著差异(P>0.05),但小叶锦鸡儿样地中芳香族含量呈表聚型分布(P<0.05)。通过随机森林模型分析发现,酸杆菌门和放线菌门分布是表层和深层土壤中灌丛化的最重要预测因子。非度量多维尺度分析(NMDS)结果表明,灌丛化显著改变了高寒草地土壤细菌群落组成(P<0.05),且植物群落结构和SOC化学组成是影响土壤细菌群落结构变化的主要因子。通过功能预测分析得到4个生物代谢通路,分别为细胞过程(Cellular processes)、环境信息处理(Environmental information processing)、代谢(Metabolism)和遗传信息处理(Genetic information processing),其中土壤微生物的代谢功能在灌丛表层和【Objective】With global climate change and overgrazing,shrub encroachment is extensively occurring in global grasslands.However,relatively little is known about how the structure of bacterial communities shifts with shrub encroachment.Thus,considering the aboveground plant community,soil carbon chemical composition,soil bacterial community structure and network beneath the canopies of three typical shrub species(Potentilla fruticosa,Spiraea alpina,and Caragana microphylla)as well as in adjacent grassland(as a control),the effects of shrub encroachment on the structure of soil bacterial communities and soil carbon pools were explored.【Method】16S rRNA gene sequencing was used to investigate the bacterial communities and co-occurrence features among bacterial taxa while Fourier transform infrared spectroscopy(FTIR)was conducted to assess the soil organic carbon(SOC)chemical composition.【Result】Shrub encroached grasslands(Potentilla fruticosa and Caragana microphylla)showed significant changes in aboveground plant community composition(P<0.01)while the aboveground plant community diversity and richness remained constant(P>0.05).The biomass of the three shrub plots was significantly higher than that of grassland(P<0.05)whereas underground biomass showed no significant difference(P>0.05).Shrub encroachment had no significant effects on SOC and total nitrogen(TN)contents,but weakened the differences of SOC contents between top-and subsoils,as shown by significantly higher SOC contents in the topsoil of the grassland than in its subsoil(P<0.05),with no such trend in the three shrub plots.The SOC chemical composition in both top-and subsoils of the three shrublands and grassland was dominated by aromatics(except for deep soil in Caragana microphylla plots),with no significant difference in aromatic content between shrub and grassland plots(P>0.05).However,the Caragana microphylla plots exhibited a surface-aggregated distribution of aromatics(P<0.05).Random forest model analysis revealed that the distribution of

关 键 词：灌丛化 微生物群落组成 土壤有机碳化学组分 微生物共生网络 植物群落 

分 类 号：S182.2[农业科学—农业基础科学]