Data from: The microbially-mediated soil organic carbon loss under degenerative succession in an alpine meadow

Land-cover change has long been recognized as having marked effect on the amount of soil organic carbon (SOC). However, the microbially-mediated processes and mechanisms on SOC are still unclear. In this study, the soil samples in a degenerative succession from alpine meadow to alpine steppe meadow in the Qinghai-Tibetan Plateau were analyzed using high-throughput technologies, including Illumina sequencing and GeoChip functional gene arrays. The soil microbial community structure and diversity were significantly (P < 0.05) different between alpine meadow and alpine steppe meadow, the microbial ɑ-diversity in alpine steppe meadow was significantly (P < 0.01) higher than in alpine meadow. Molecular ecological network analysis indicated that the microbial community structure in alpine steppe meadow was more complex and tighter than in the alpine meadow. The relative abundance of soil microbial labile carbon degradation genes (e.g., pectin and hemicellulose) was significantly higher in alpine steppe meadow than in alpine meadow, but the relative abundance of soil recalcitrant carbon degradation genes (e.g. chitin and lignin) showed the opposite tendency. The Biolog Ecoplate experiment showed that microbially-mediated soil carbon utilization was more active in alpine steppe meadow than in alpine meadow. Consequently, more soil labile carbon might be decomposed in alpine steppe meadow than in alpine meadow. Therefore, the degenerative succession of alpine meadow because of climate change or anthropogenic activities would most likely decreased SOC and nutrients medicated by changing soil microbial community structure and their functional potentials for carbon decomposition.

长期以来，土地覆被变化对土壤有机碳（soil organic carbon, SOC）的含量具有显著影响已成为学界共识，然而其中微生物介导的土壤有机碳转化过程与作用机制仍未明晰。本研究针对青藏高原上从高寒草甸向高寒草原草甸的退化演替序列采集土壤样品，采用Illumina测序、GeoChip功能基因芯片等高通量技术开展分析。结果显示，高寒草甸与高寒草原草甸的土壤微生物群落结构与多样性存在显著差异（P < 0.05），且高寒草原草甸的微生物α-多样性显著高于高寒草甸（P < 0.01）；分子生态网络分析表明，高寒草原草甸的微生物群落结构较高寒草甸更为复杂且连接更紧密。高寒草原草甸土壤微生物的易分解碳降解功能基因（如果胶、半纤维素相关基因）的相对丰度显著高于高寒草甸，而难分解碳降解功能基因（如几丁质、木质素相关基因）的相对丰度则呈现相反的变化趋势；Biolog Ecoplate实验结果显示，高寒草原草甸中微生物介导的土壤碳利用活性显著高于高寒草甸。据此推测，高寒草原草甸中相较于高寒草甸会有更多的土壤易分解碳被微生物分解，因此受气候变化或人为活动驱动的高寒草甸退化演替，极有可能通过改变土壤微生物群落结构及其碳分解功能潜力，降低土壤有机碳与养分水平。