Abstract: In order to reveal the changes of soil quality, effects of fencing on soil organic carbon and its active components were analyzed in the degraded desert grassland of northern slope. The changes of soil organic carbon (SOC), readily oxidation carbon (ROC), microbial biomass carbon (MBC) and labile organic carbon/soil organic carbon (MBC/SOC, ROC/SOC) ratios in both fencing and grazing grasslands were comparatively investigated. Results showed that the soil organic carbon and active component contents of grazing treatments were higher than that of 5-year fencing treatment. The soil organic carbon, microbial biomass carbon and MBC/SOC of grazing treatments significantly increased by 0.81 g·kg^-1, 34.12 mg·kg^-1 and 0.59% in 5～10 cm soil layer (P<0.05), respectively. And readily oxidation carbon contents and ROC/SOC ratios had significant difference between grazing and fencing treatments in 10～15 cm soil layer (P<0.05). These results indicated that the soil quality of desert grassland decreased after 5-year fencing. Therefore, some reasonable fencing-grazing systems should be implemented, which would be beneficial to the restoration of degraded desert grassland ecosystem.

Key words: Desert grassland, Fencing, Soil organic carbon, Labile organic carbon

摘要： 以天山北坡中段退化荒漠草地为研究对象，通过分析封育与放牧对草地土壤有机碳、易氧化碳、微生物量碳含量及活性有机碳的分配比例的影响，以揭示土壤质量的变化。结果表明：禁牧封育5年后草地土壤有机碳及其活性组分含量低于放牧草地。与封育草地相比，在5～10 cm放牧草地土壤有机碳、微生物量碳及MBC/SOC显著升高（P<0.05），分别增加了0.81 g·kg^-1，34.12 mg·kg^-1，0.59%；土壤易氧化碳含量及ROC/SOC在10～15 cm土层差异均达显著水平（P<0.05）。可见，荒漠草地在封育5年后土壤质量降低，因此，应该实行合理的围封-放牧体系，更有利于退化荒漠草地生态系统的恢复。

关键词: 荒漠草地, 封育, 土壤有机碳, 活性有机碳