北京东灵山林线上下土壤微生物的时空分异研究

Montane ecosystem is an ideal environment for studying temporal and spatial variations in soil microbial communities. Alpine treeline, as an important ecosystem boundary of natural vertical zones, is extremely sensitive to climate change. Climate warming leads to movement of the treeline toward a higher elevation, but little is known about the dynamics of microbial communities and functions under this change. Though encouraging progress has been made on elevational distribution of microbial communities recently, our knowledge of microbial temporal variations and underlying mechanisms of community assembly is still limited, as well as the relationship between microbial communities and functions. This project intends to select soil samples of two different vegetation types above and below treeline on Dongling Mountain, Beijing. Soil samples will be collected in different temporal gradient and elevational gradient, aiming to study temporal and elevational variations for soil characteristics, microbial communities and soil multifunctionality. Our project will be benefit for understanding dynamics of soil microbial communities and functions, underlying mechanisms of temporal and elevational microbial diversity patterns, and relationships between microbial communities and functions. These results can also provide theoretical basis for predicting the responses of montane ecosystems to climate change.

山地生态系统是研究土壤微生物时空分异规律的理想环境。高山林线作为垂直自然带上的一条重要的生态系统分界线，对气候变化极为敏感。气候变暖可能导致林线向海拔更高处迁移，然而林线附近土壤微生物群落和功能如何变化却很少有人关注。近些年研究者在揭示土壤微生物海拔分布规律方面取得了很大进展，但对于微生物时间动态的变化规律、微生物时空分布的潜在影响机制及微生物群落与功能的关系，这些方面的认知仍然十分有限。本项目拟选择北京东灵山为研究对象，针对林线上下不同植被类型土壤，采集不同时间梯度和海拔梯度土壤样品，研究土壤特性、微生物群落和功能的时间动态变化和海拔分布规律。通过这些研究，系统了解山地生态系统不同植被类型土壤微生物群落和功能的时间动态变化规律，阐明林线上下土壤微生物群落和功能的分异规律及驱动机制，揭示土壤微生物群落与功能的关系，进而为预测山地生态系统对气候变化的响应提供理论依据。

山地生态系统是研究土壤微生物时空分异规律的理想环境。尽管微生物多样性的海拔分布格局已经被广泛报道，但我们对微生物多样性海拔模式是否受季节影响知之甚少。为探究季节效应和海拔效应对微生物群落和功能的影响，我们在三个季节（春，夏，秋）于北京东灵山林线上下不同海拔梯度采集土壤样品，通过16SrRNA, 18SrRNA和nifH基因测序研究了微生物的多样性，通过测定基础呼吸和微生物生物量研究了微生物功能。我们发现，土壤微生物alpha和beta多样性及微生物功能具有显著的海拔分异和季节变化，且海拔效应大于季节效应。微生物beta多样性和微生物功能的海拔模式不受季节影响，但微生物alpha多样性的海拔模式可随季节而改变。进一步研究，我们鉴定出4个土壤因子（即含水量、总碳、总氮和硝态氮）有较高的季节和海拔变化，这些因子是主导微生物多样性和功能时空分异的关键因素。因此，这项研究表明了季节性对微生物alpha多样性（而非beta多样性和功能）海拔模式的影响。研究结果为理解微生物群落和功能的海拔季节效应提供了新的见解。