放牧对羊草草原土壤氮素循环的影响

研究了放牧对内蒙古羊草草原土壤中N素分解细菌以及固N作用、氨化作用和硝化作用的影响,结果表明,轻度放牧使土壤中4类N素转化细菌的数量显著增加,也显著加强了土壤中的固N作用、氨化作用和硝化作用。促进了土壤中的N素循环;随放牧强度的增加,重度放牧则导致草原土壤中4类N素转化细菌数量均显著降低。显著抑制土壤中的固N作用和氨化作用,会阻碍土壤中的N循环的进程。放牧强度对N素转化细菌以及N循环中的固N作用、氨化作用和硝化作用的季节性变化规律无明显影响。

Study on effect of grazing on steepe soil nitrogen cycle

The effects of grazing on nitrogen cycle bacteria, nitrogen fixation, ammonification and nitrification were studied in Leymus chinensis steppe in Inner Mongolia. The results showed that light grazing increased significantly the amounts of four types of nitrogen cycle bacteria and the intensities of soil nitrogen fixation, ammonification and nitrification, and promoted the circulation of soil nitrogen, but heavy grazing produced the converse trend. Grazing intensity had no significant effect on the seasonal variation of nitrogen cycle bacteria, nitrogen fixation, ammonification and nitrification.