在青海省祁连山冰沟流域的高山草甸土上,选择放牧与禁牧2个样品采集区,研究了禁牧对祁连山冰沟流域高山草甸土有机碳及理化性质和酶活性的影响.结果表明:高山草甸土遭到放牧牲畜连续3年的啃食和践踏后,植被覆盖度明显降低,归还到土壤中的生物量和枯落物积累量减少,0～20 cm土层有机质含量、有机碳密度、总孔隙度、团聚体、田间持水量、氮磷钾和酶活性降低,容重、caCO3和可溶性盐增加,但20 cm以下土层这些性质变化不大.放牧与禁牧比较,0～20 cm土层土壤容重、可溶性盐和CaCO3分别增加14.15％、6.35％和1.27％;有机碳含量、有机碳密度、总孔隙度、团聚体和田间持水量分别降低29.76％、22.82％、9.45％、6.49％和7.69％;全氮、全磷、全钾、脲酶、蔗糖酶、磷酸酶和过氧化氢酶分别降低25.97％、15.56％、12.17％、33.77％、26.11％、42.00％、29.31％.放牧对有机碳、容重、孔隙度、田间持水量、可溶性盐、氮磷钾和酶活性影响深度为20 cm,对团聚体影响深度为40 cm.%The experiment was conducted to determine the influence of banning grazing on alpine meadow soil organic carbon,physio-chemical properties and enzyme activities at Ice Valley,Qilian Mountain.The results showed that the vegetation coverage,soil biomass and organic matter content of alpine meadow soil were decreased significantly after grazing for three years.Organic matter content,organic carbon density,total porosity,aggregate,field capacity,NPK content and enzyme activity at 0 ～ 20 cm layer was decreased,and soil bulk density,CaCO3 and soluble salt content was increased.Compared with grazing,the soil bulk density,CaCO3 and soluble salt content at 0 ～ 20 cm layer in area of grazing prohibition were increased by 14.15％,6.35％,and 1.27％,and organic matter content,organic carbon density,total porosity,aggregate,and field capacity by 29.76 ％,22.82 ％,9.45 ％,6.49 ％,and 7.69 ％,respectively;while the urease,sucrase,phosphatase and calatase activities and total NPK was reduced by 33.77％,26.11％,42.00％,29.31％,25.97％,15.56％ and 12.17％,respectively.In conclusion,the influencing depth of grazing on organic carbon,soil bulk density,total porosity,field capacity decreased,soluble salt content,NPK and enzyme activity was 0 ～ 20 cm soil depth,whereas that on aggregate was 0 ～ 40 cm soil depth.
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