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（SOC）的含量具有显著影响已成为学界共识。然而，其调控土壤有机碳的微生物介导过程与作用机制仍有待阐明。本研究以青藏高原上从高寒草甸向高寒草原草甸的退化演替序列土壤样品为研究对象，采用高通量技术手段开展分析，包括Illumina测序（Illumina sequencing）与GeoChip功能基因芯片（GeoChip functional gene arrays）。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及多样性存在显著差异（P < 0.05）；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。高寒草原草甸中土壤微生物活性碳降解基因（如果胶、半纤维素降解基因）的相对丰度显著高于高寒草甸，而难降解碳降解基因（如几丁质、木质素降解基因）的相对丰度则呈相反趋势。Biolog Eco板实验结果显示，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。由此推测，相较于高寒草甸，高寒草原草甸中更多的土壤活性碳会被分解。因此，受气候变化或人为活动驱动的高寒草甸退化演替，大概率会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储量。