哀牢山亚热带常绿阔叶林土壤微生物多样性对碳输入变化和增温的响应

Response of soil microbial diversity to carbon input and warming in a subtropical evergreen broad-leaved forest at Ailao Mountain

为掌握哀牢山亚热带常绿阔叶林土壤微生物多样性对碳输入变化和增温的响应,本研究基于云南哀牢山亚热带常绿阔叶林模拟增温实验平台,以去除地表凋落物、切根、切根并增温和对照4个处理6 a后表层矿质土壤(0~10 cm)为研究对象,测定土壤理化性质和微生物群落组成,探讨土壤微生物多样性对碳输入和增温处理的响应和驱动因子。研究结果表明,碳输入和增温处理未改变哀牢山亚热带常绿阔叶林土壤微生物的优势菌群,各处理的细菌优势菌门为变形菌门和酸杆菌门,真菌优势菌门为子囊菌门和担子菌门。与对照处理相比碳输入和增温处理改变了土壤微生物群落的α多样性指数,切根处理显著降低细菌Shannon指数和Chao1指数,而切根并增温处理的Shannon指数和Chao1指数显著升高。与切根处理相比,切根并增温使土壤细菌群落结构发生显著改变。冗余分析显示,处理间细菌群落结构差异的主要调控因子为土壤温度、土壤含水量、土壤全磷和土壤全钾,其中土壤温度和土壤含水量的影响最大;土壤细菌群落对碳输入变化和增温的响应比真菌群落更为敏感。

This study investigated the response of soil bacterial and fungal diversity to soil warming and changes in carbon input in a subtropical evergreen broad-leaf forest.We used a long term soil warming platform,which had been in place for 6 years,to detect soil microbial diversity.We collected surface soil(0-10 cm) from control,litter removal,trenching,and trenching and warming treatments to determine the physical and chemical characteristics(total carbon,nitrogen,phosphorous,and potassium content,NH_4~+-N,NO_3~--N,soil water content,and soil temperature) and microbial community composition.The results revealed that carbon input and warming treatment did not alter the dominant flora of soil microorganisms in the subtropical evergreen broad-leaf forest of Ailao Mountain.The dominant bacteria were Proteobacteria and Acidobacteria,and the dominant fungi were Ascomycota and Basidiomycota.However,carbon input and warming treatments did alter the alpha diversity index of the soil microbial community:trenching significantly decreased the Shannon and Chao1 indices of bacteria,whereas trenching and warming significantly increased the Shannon and Chao1 indices.Further,trenching and warming treatments significantly changed the structure of the soil bacterial community.Redundancy analysis revealed that temperature,water content,total soil phosphorus and potassium were significantly related to the structure of the bacterial community,with soil temperature and water content being the important factors.Overall,these findings suggest that the soil bacterial community was more sensitive to changes in carbon input and soil warming than the fungal community in the subtropical evergreen broad-leaf forest of Ailao Mountain.