高寒草地土壤细菌对放牧梯度的响应

Response of Soil Bacteria Diversity to Grazing in Alpine Grassland

放牧作为影响土壤微生物群落的重要因素,对土壤细菌的生长、活动、生存具有重要的影响。青藏高原地区放牧是主要的草地利用方式,而放牧条件改变引起的生境变化成为土壤微生物群落结构及其多样性变化的关键因子。目前关于放牧对草地土壤微生物多样性影响的结论并不统一。采用Hiseq高通量测序对放牧梯度下西藏高原典型高寒草地土壤细菌群落进行检测发现:不同放牧梯度下土壤细菌的物种多样性在中度放牧下最高,而均匀度没有显著变化。其优势物种相对丰度随放牧强度表现出显著差异,其中Pseudonocardia、Sporosarcina、Thermomonas相较于中-弱放牧梯度在强放牧强度下相对丰度增大,而Rhodoplanes、Microlunatus在强放牧作用下相对丰度表现为减小。门水平上细菌类群间相关性随放牧梯度而变化,且细菌群落结构和位置在不同放牧强度下显示出显著差异。

As the key factors to soil microbial community,grazing influents the growth, activities and survival of soil bacteria significantly. Grazing is the premier land use pattern of Tibetan Plateau and the habitat condition transform caused by livestock grazing in Tibet turns into the key factor influent grassland soil bacteria structure and diversity. Previous researchs about the response of soil bacteria diversity to grazing were various in different grassland. The diversity and composition of the alpine grassland soil bacteria was investigated in the dual gradient of grazing with Hiseq high-throughpnt sequencing. The results were demonstrated as the followed：The moderate grazing increased the species richness in moderate intensity contrast to high and low grazing intensity while the evenness of soil bacteria showed no significant change with grazing gradient. The relative abundance of dominant species showed discrepancy with various grazing intensity. Pseudonocardia, Sporosarcina, Thermomonas increased while Rhodoplanes ,Microlunatas decreased in high grazed gradient than moderat-low grazed gradient. The correlation of primary phyla change with various grazing intensity and the structure and composition of soil bacteria also demonstrated the dissimilarities among heavy ,moderate and low grazed gradient.