高寒森林溪流凋落叶分解过程中的微生物群落演变

The shift of microbial community during the process of litter decomposition in the high-frigid forest streams plays an essential role in understanding not only the key ecological content of the material cycle of the stream ecosystem and the flowing of energy, but also the ecological relationship between land and water of the alpine forest. However, little information has been available on. Therefore, it is hypothesized that the structure of microbial community can be profoundly affected by seasonal climate change of high-frigid forest streams in the pattern of snowcover and freezing-thawing, and then the key ecological process of litter decomposition and its related key ecological process will be regulated”. Litterbages with leaf/needle litter of four respresentative species will be placed in the high-frigid forest streams of western Sichuan with snowcover for 5 to 6 months every year. Samples will be taken at the five key stages of snow forming, snow covering, snow melting, early and late stage of growing season. The dynamics of microbial community structure characteristics (the microbial biomass, community composition, abundance, and biodiversity and so on) and the corresponding changes of litter weight loss and quality characteristics during litter decomposition will be analysed by the methods of tranditional chemical experiments united with real-time fluorescent quantitative PCR and high-throughput genetic sequencing. The relationships of these parameters among the five key stages will be aslo explored in combining with the dynamics of temperature and water environment monitoring at different stages. The results could be expected to further understand the dynamic shift of microbial community during the process of litter decomposition in the high-frigid forest ecosystem, and to reveal the ecological relationships between the litter decomposition process and the shift of microbial community. Moreover, the results will be helpful to predict the process of litter decomposition in the alpine forest streams ecosystem and its related material recycling and energy transformation in the scenario of ongoing climate change.

高寒森林溪流凋落物分解过程中的微生物群落演变不仅是认识溪流生态系统物质循环与能量流动等关键生态学过程的重要内容，而且对于了解高寒森林陆地与水体间的生态联系具有重要意义，但缺乏必要关注。基于“受雪被和冻融影响，高寒森林溪流季节性环境变化可深刻影响微生物群落结构，进而调控凋落物分解及其相关的关键生态学过程”的科学假设，拟以年积雪达5-6个月的川西高寒森林溪流为平台，采用凋落物分解袋法、实时荧光定量PCR法及高通量测序法，在雪被形成期、雪被覆盖期、雪被消融期、生长季前期及后期研究高寒森林溪流凋落叶自然分解过程中微生物的生物量、群落组成、丰度、及多样性等结构特征及其与凋落叶分解的相互关系，结合同步温度动态和水环境特征监测，分析凋落叶分解过程中微生物群落结构的动态演变过程，探讨凋落叶分解过程与微生物群落演变间的相互作用机制，以期为深入认识高寒森林溪流凋落物分解及其相关的物质与能量过程提供科学理论依据

本研究紧密围绕揭示高寒森林溪流凋落叶分解过程中的微生物群落演变这一中心目的展开。立足于溪流生态环境，并通过不同生态环境的对比，以海拔3600 m，年积雪时期长达5-6个月的川西高寒森林、溪流、河流和河岸带四个同一区域不同性质的生态环境为平台，以区域内冠层优势物种方枝柏和四川红杉、河岸优势植物康定柳和高山杜鹃的凋落叶为研究对象，在雪被形成期、雪被覆盖期、雪被消融期、生长季前期和生长季后期，研究了高寒森林、溪流、河流和河岸带凋落叶分解过程中微生物（细菌、真菌和古菌，以及担子菌和好氧不产氧光合菌）群落结构的演变过程，及其分解过程中微生物群落结构演变对溪流环境季节性变化的响应。在凋落叶的分解过程中，季节性变化、冻融循环和土壤冻结、环境的差异及凋落叶的异质性综合作用于微生物的丰度和群落结构，导致各微生物类群的丰度和结构及其变化在同一生境的不同凋落叶之间，或不同生境的同种凋落叶之间，以及随凋落叶的分解进程均产生了巨大的差异。最终在不同程度上作用于凋落叶的分解。研究结果为深入认识高寒森林凋落物分解及其相关的物质与能量过程提供了科学理论依据。

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