小兴安岭森林湿地不同过渡带土壤微生物群落结构研究

Research on Soil Microbial Community Structure of Different Forest-wetland Ecotones in Xiaoxing'an Mountain

土壤微生物群落是生态功能的基础。为了揭示土壤微生物群落结构对森林湿地不同过渡带生境的响应,以小兴安岭的退化森林湿地为研究对象,沿森林至沼泽过渡带环境依次分布的4种典型沼泽湿地:白桦-落叶松(Betula platyphylla-Larix olgensis)、毛赤杨(Alnus sibirica)、油桦(Betula ovalifolia)、苔草(Carex schmidtii)分别采集0~<10 cm土壤样品。采用磷脂脂肪酸(PLFAs)生物标记法分析不同过渡带土壤微生物群落结构的变化规律。结果表明:不同过渡带土壤中共检测到57种PLFA生物标记,PLFA总含量在4.06~11.06/μg/g之间,优势PLFA生物标记是16:0N ALCOHOL、16:0、18:1ω7c和16:1ω7c。土壤微生物PLFA的种类和总量沿森林至沼泽过渡带环境梯度递减,即白桦-落叶松>毛赤杨>油桦>苔草土壤。细菌、真菌PLFA含量变化趋势与PLFA总量一致,放线菌的PLFA含量表现为白桦-落叶松>油桦>毛赤杨>苔草土壤。土壤微生物多样性指数的Shannon-Wiener指数、Simpson丰富度指数在白桦-落叶松、油桦沼泽湿地中显著大于其他土壤,而土壤微生物的Pielou指数表现为油桦、苔草土壤显著大于其他土壤。RDA分析表明土壤有效氮含量、p H是影响土壤微生物群落的重要因子。总之,不同过渡带的土壤微生物群落结构存在差异,在监测和治理小兴安岭森林湿地生态系统时应考虑土壤微生物群落的空间分布特征。

Soil microbial community is the basis of ecological function. To understand the changes in the soil microbial community structure in response to biotopes of different forest-wetland ecotones, the study was located in Xiaoxing＇an Mountain, a degraded forest wetland, and the soil in the depths of 0~〈10 cm was collected from four typical swamp forests in this area. The four swamp forests were Betula platyphylla-Larix olgensis,Alnus sibirica,Betula ovalifolia,Carex schmidtii in the ecotones from forest to swamp. Soil microbial community structure under different forest-wetland ecotones was analyzed by phospholipid fatty acid （PLFA） biomarker methodology. The result showed that 57 kinds of phospholipid fatty acids were detected in the soil of different ecotones, the total PLFA content of soil microbes was between 4.06~11.06 （JLg.g-1. 16：0N ALCOHOL, 16：0,18：1 a） 7c and 16：1 〇 〉 7c were the dominant PLFA in the soil of four forest-wetland ecotones. The species and content of PLFAs biomarkers present a gradient decrease along the ecotones from forest to swamp, which were all characterized by Betula platyphylla- Larix olgensis〉Alnus sibirica〉Betula ovalifolia〉Carex schmidtii. The contents of bacteria, fungi and gram-positive bacteria PLFA presented consistent tendency with total PLFA content. The content of actinomycetes PLFA followed the order of Betula platyphylla-Larix olgensis〉Betula ovalifolia〉Alnus sibirica 〉Carex schmidtii. The Shannon-Wiener index, Simpson index of Betula platyphylla-Larix olgensis and Betula ovalifolia were significantly higher than those of the other swamp forest types. The Pielou index of Betula ovalifolia and Carex schmidtii was significantly higher than those of the other swamp forest types. Theresults of redundancy analysis showed that available N and pH value were the main factors influencing soil microbial community. In conclusion, the soil microbial community structure was significandy different among different forest-wetland ecotones. The spatial distribution characteristics of soil microbial community should be considered in the monitoring and management of the forest wetland ecosystem in Xiaoxing＇an Mountain.