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2020/09/28 19:38 |
魏培洁 |
中国科学院西北生态环境资源研究院 |
论文题目：Soil microbial distribution in active layers of permafrost ecosystems under a degradation gradient
论文摘要：Permafrost is a unique habitat for microbial life on Earth and is considered to be a vast repository of ancient viable cells. Admittedly, global warming has triggered permafrost degradation over the past several decades. Such degeneration has acutely influenced the alpine ecosystem containing changes of soil hydrothermal status, soil nutrient content and distribution of vegetation, and further threaten the ecological balance and stability. As the permafrost thaws and the organic material becomes more accessible to microorganisms, microbial diversity and activity also increase. This could result in a large positive feedback to the greenhouse effect. However, there are few studies on the distribution of soil microbes under the natural gradient of permafrost degradation. New tools and methods give us unprecedented abilities to survey individual microbial communities and document changes in microbial communities across space or time. To investigate the microbial community structures, biogeographic patterns and the mechanisms underlying community similarity in permafrost zones, we conducted seven plots across five permafrost types in the upstream regions of the Shule River Basin in the western Qilian Mountain, which 42 soil samples were collected and analyzed with three microbial taxa (bacteria, fungi and archaea) totally by using high-throughput sequencing. Of all samples surveyed, we obtained altogether 2878381, 2732217 and 2620712 sequences of bacteria, fungi and archaea. Dominant phyla of microbial taxa in each of the permafrost degraded stages and vegetation types were almost same and consistent who were Proteobacteria, Acidobacteria, Bacteroidetes, Actinobacteria, Ascomycota, Zygomycota, Basidiomycota and Crenarchaeota, and the permafrost degradation significantly affected the relative abundance of bacterial dominant phyla while had no influence on fungi and archaea. Meanwhile, alpha diversity, as estimated by richness (observed OTUS) and Shannon index, varied strikingly across permafrost degraded stages and vegetation types. Along the degradation gradient of permafrost, α-diversity levels of soil bacteria, fungi, and archaea were significant decreasing, except the fungal Shannon index. Across all the microbial community taxa, both environmental factors and elevation significantly influenced microbial β-diversity. Community similarities versus elevation drop and environmental distance clearly displayed significant distance–decay relationships (DDR) for microbial communities. DDR were prominent in soil microbes, which were manifested in two forms. (i) The decay rates in different microbial taxa were drastically different, presenting archaea > bacteria > fungi; (ii) Aside from archaea, the decay rates in different stabilities of permafrost were quite different, showing stable > unstable. These modes could be explained well by the corresponding extent and manner of the microbial community to the environment data. Temperature and active layer thickness had notably influenced on the microbial composition, more importantly, the degree of influence rates (decay slopes) of different microbial taxa were markedly distinct, displaying bacteria > archaea > fungi. Differed from bacteria and fungi, archaea was maximally affected by total nitrogen content and soil microbial biomass nitrogen which may cause the steepest decay rate in archaea with environmental distance. And the same results also explained the different decay rates within stabilities. Our findings suggested that microbial taxa had variety of driving patterns, which had important implications for assessing the effects of climate changes, permafrost degradation and other factors.
论文类型 期刊论文 |
