大兴安岭多年冻土微生物群落结构及其对冻融变化的响应

Degradation of permafrost caused by global climate change will nonlinearly affect the original intensity, depth and frequency of the freezing and thawing of permafrost regions in the Da Hinggan Mountains. The changes in freezing and thawing will further break and change the inherent survival mode of permafrost microorganisms and then change the biogeochemical cycle by influencing their metabolic pathways and increase the uncertainty of their predictions of climate change. The Illumina high-throughput sequencing technology and the method of substituting space for time are intended to be used in this study. This study aims at revealing the response and adaptation mechanisms of soil microorganisms to changes in freezing and thawing. The variation characteristics of microbial community structure, microbial diversity, microbial biomass and the activity of relevant soil enzymes of different types of permafrost including continuous permafrost, island melting permafrost zone and island permafrost will be systematically researched by in situ monitoring. The results of the research will be helpful for evaluating and predicting the influence of global climate change to the function and stability of forest ecosystems in permafrost regions.

全球气候变化导致的多年冻土退化，将非线性地影响大兴安岭多年冻土区原有的冻融强度、深度和频率，进一步打破和改变冻土微生物已有的生存模式，进而通过影响其代谢途径改变生物地球化学循环，增加其预测气候变化的不确定性。本项目拟运用Illumina 高通量测序技术，采用以空间代时间的方法，通过野外原位监测，系统研究大兴安岭不同类型冻土带（连续多年冻土带、岛状融区冻土带和岛状冻土带）微生物群落结构、微生物多样性、微生物量及相关土壤酶活性的变化特征，揭示土壤微生物对冻融作用变化的响应与适应机制。上述研究结果将有助于准确评估和预测全球气候变化对多年冻土区森林生态系统功能和稳定性的影响。

大兴安岭多年冻土区处于欧亚大陆冻土带南缘，是我国特有的高纬度多年冻土，冻土厚度较薄、热稳定性差，对气温升高和外界环境变化极为敏感。本项目运用微生物分子生态学和生物地球化学的技术手段，分析大兴安岭多年冻土区不同时空尺度上微生物的分布格局、演替特征及其维持机制，阐明多年冻土退化后微生物群落结构变化的关键环境控制因子，重点关注冻融作用（冻融强度、冻融时间和季节性冻融）变化对土壤生化特性和微生物的影响机制。冻融作用变化显著改变土壤活动层微生物群落结构和多样性，土壤冻结期间仍有较高的微生物活性，真菌比细菌对干冷环境变化有更高的耐受能力。同时还利用多年冻土地温观测系统，解析大兴安岭不同林型下冻土的冻结消融规律，揭示土壤冻融格局和微生物群落结构对环境变化响应特征。研究成果有助于强化对多年冻土区森林土壤生态系统过程的理解，丰富高纬度寒区森林生态和土壤微生物生态研究的内容。