长期围封和自由放牧对高寒草甸土壤微生物群落结构及碳源代谢多样性的影响

土壤微生物群落结构和代谢多样性对于维持草地生态系统的功能和稳定性具有重要意义.本研究运用磷脂脂肪酸法(PLFA法)和Biolog微平板技术,研究了青藏高原长期围封和自由放牧2种草地利用方式下的土壤微生物群落结构和群落碳代谢多样性的差异以及影响机制.结果表明: 1)长期围封和自由放牧草地上的土壤微生物群落结构和碳代谢多样性存在显著差异;2)长期围封显著增加了土壤中总PLFA、细菌、真菌和放线菌生物量;3)长期围封草地土壤微生物的碳代谢活性、多样性和丰富度高于自由放牧草地,而均匀度低于放牧草地;4)与自由放牧相比,长期围封显著增加了土壤微生物对聚合物类、糖类、羧酸类、胺类碳源的利用;5)冗余分析表明,植被盖度显著影响了微生物的群落结构和碳代谢多样性.长期围封草地的土壤微生物量、碳代谢多样性指数和丰富度均高于自由放牧土壤,表明长期围封有利于提高草地生态系统中土壤微生物群落及其对碳源代谢的多样性.

Influence of long-term enclosure and free grazing on soil microbial community structure and carbon metabolic diversity of alpine meadow.

Soil microbial community structure and functional diversity have great implications for the maintenance of the function and stability of grassland ecosystem. We studied the variation of soil microbial community structure, community diversity of carbon metabolism and their driving factors between the long-term enclosure and the free grazing grasslands in Qinghai-Tibet Plateau by using phospholipid fatty acid and Biolog techniques. The results showed that: 1) there were significant differences in soil microbial community structure and the utilization of carbon source between the long-term enclosed and free grazed grasslands. 2) Long-term enclosure significantly increased the content of total PLFA, bacteria, fungi and actinomycetes. 3) Soil carbon metabolic activity, diversity and richness in free-grazing grassland was significantly higher than the enclosed grassland, but evenness showed an opposite pattern. 4) Compared with the free grazed grassland, long-term enclosure significantly increased the utilization of polymers, carbohydrates, carboxylic acids, and amines by soil microorganisms. 5) Results from the redundancy analysis showed that vegetation coverage significantly affected soil microbial community structure and carbon metabolism. The soil microbial content, carbon metabolism diversity and richness in the long-term enclosed grassland were higher than those of the free grazing grassland, indicating that long-term enclosure was more conducive to improve the diversity and carbon metabolism of soil microbial community.