围栏禁牧对高寒草原土壤微生物碳源利用的影响

Effects of enclosure on soil microbial carbon utilization in an alpine steppe

为解析围栏禁牧与高寒草原土壤微生物碳源利用的关系,以藏北高寒草原为对象,对比研究了5年围栏禁牧和连续自由放牧条件下高寒草原土壤碳氮和微生物碳源利用情况。结果表明:1)围栏禁牧后,土壤溶解性有机碳、氮含量分别增加了26.60%和28.13%,但有机碳和全氮无明显变化;2)围栏禁牧提高了土壤微生物生物量、土壤酶活性和微生物群落的丰富度指数,但对微生物群落均匀度和优势度指数无明显影响;3)围栏禁牧增加了土壤微生物对碳水化合物、氨基酸类、多聚物类和胺类碳源的利用。由此可见,围栏禁牧最初是通过改变土壤溶解性有机碳氮、微生物活性和群落结构来重塑土壤生态功能,进而促进受损或退化高寒草原土壤生态系统的恢复。

In order to understand the effects of enclosure on the utilization of soil microbial carbon source in alpine steppe,the soils under 5-year enclosure and continuous free grazing were sampled to determine soil carbon and nitrogen,and soil microbial carbon source utilization in alpine steppe of the northern Tibet.The results showed that:1)compared to free grazing,the contents of soil dissolved organic carbon and nitrogen increased by 26.60%and 28.13%,respectively,but there were no significant changes in organic carbon and total nitrogen between enclosure and grazing steppes;2)enclosure increased soil microbial biomass,soil enzyme activity and microbial richness index,but had no significant impacts on evenness and dominance indexes;3)enclosure significantly increased the utilization of carbohydrate,amino acid,polymer and amine carbon sources by soil microorganisms.It can be concluded that enclosure reconstructs soil ecological function by changing soil dissolved organic carbon and nitrogen,soil microbial activity,as well as soil microbial community structure firstly,and then promotes the recovery of the damaged or degraded alpine steppe soil ecosystem.