Abstract: Effect of stocking rates on number and biomass of soil microorganism was researched in the degraded Atremisia frigida and short-grasses communty Inner Mongolia China.There were five treatments in the control led condition:1.33,4 and 6.67 sheep/ha(3×15d/year),4 sheep/ha(120d/year)and ungrazing.The results showed that the number and biomass of soil microorganisms significantly increased(p<0.01)in the ungrazing and different stocking polts in the fenced than that of the outside.In comparison with ungrazing plot,plots of different stocking had made lower microorganisms with different groups after 4years.There was a positive correlation between microorganisms with soil organic C(p<0.01).Microbial biomass-C was the high in the plot of 4 sheep/ha than that of ungrazing,but low in plots of 1.33 and 6.67sheep/ha.Long term light grazing(4 sheep/ha,120d/year)did not show significant effect on soil microorganisms after 9 years.The results also indicated the degenerative steppe could be relatively restored by ungrazing or light grazing.

Key words: Artemisia frigida and short-grasses community, Stocking rate, Soil microorganism

摘要： 以围栏轮牧方式研究不同放牧率对退化草原土壤微生物的影响。结果表明,围栏及适度放牧四年后使土壤微生物的数量显著提高(P<0.01),有利于退化草原的逐步恢复。与对照区比较,放牧区微生物各类群的数量均呈减少趋势,并与土壤有机碳变化密切相关(P<0.01)。九年后,在4羊/ha区的微生物量-C高于对照区,而在1.33和6.67只羊/ha区则有所降低。长期中牧(4只羊/ha)对土壤微生物总数无显著影响。

关键词: 冷蒿和小禾草草原, 放牧率, 土壤微生物