Abstract: Alpine grassland degradation has an important impact on the carbon cycle of grassland ecosystems.To investigate the soil organic carbon density changes during different process of grassland degradation will have important theoretical value to the evaluation of alpine grassland soil carbon sequestration capacity and maintenance of climate change.The objective was mainly to discuss the variation characteristics of soil organic carbon density under the interference of grassland degradation.Three different degradation degrees,namely light,moderate,and heavy,of alpine grasslands were chosen in Tianzhu area located in the eastern of Qilian Mountain in 2008.Research results show that the soil water content decreased and bulk density and pH value increased along with the increasing of degradation degree.Soil organic matter and total nitrogen showed similar change trend and significant difference existed between moderate and light or heavy degradation degree(P<0.05).Soil organic carbon density in 0-10 cm soil layer was significant higher than other soil layers and significant vertical change trend occurred along with the increasing of soil depth.In 0-30 cm soil layer of grasslands with different degradation degrees,the sequence of total organic carbon density was moderate degradation degree>light degradation degree>heavy degradation degree.

Key words: Soil organic carbon density, Alpine grassland, Different degradation degree

摘要： 于2008年在祁连山东段天祝地区选取轻度、中度和重度3个不同退化程度的高寒草地,以土壤有机碳密度为研究对象,探讨高寒草地在不同退化程度干扰下土壤有机碳密度的变化特征。结果表明:随着高寒草地退化程度的加重,土壤含水量降低,容重和pH值增大;土壤有机质和全氮有相似的变化趋势,中度与轻度或重度退化草地土壤有机质和全氮差异显著(P<0.05);土壤有机碳密度在0-10 cm土层显著高于其他土层(P<0.05),并随着土层加深有显著的垂直变化趋势;不同退化程度草地在0-30 cm土层总土壤有机碳密度表现为中度>轻度>重度退化草地。

关键词: 土壤有机碳密度, 高寒草地, 不同退化程度