Abstract: Based on different degradation of typical sloping land of alpine meadows in the Three-River Headwaters Region, the changes of soil erosion and soil physical and chemical properties under the different sloping positions were revealed. It was vital for the changes of soil physical and chemical properties due to natural erosion after grassland destruction for stocking. Results were as follows. The soil organic carbon (SOC), soil total nitrogen (STN) and ¹³⁷Cs contents of slight and moderate degradation slopes presented small differences; those of extreme degradation and moderate degradation slopes were significantly higher than that of severe degradation slopes (P<0.05). Not only SOC and TSN show a basic downward trend with the increasing of degradation, but also performed transportation along the alpine meadow slope after degradation due to soil erosion. Under slope erosion conditions, the SOC and STN contents of alpine meadow in the different gradients showed significant (P<0.05) differences. Compared with lightly degraded meadow, the average SOC and TSN contents of moderate, severe and extreme degraded meadows decreased 3.3% and 2.6%, 60.2% and 55.3%, 40.6% and 32.4% (P<0.05), respectively. Soil erosion modulus in alpine meadow increased with the increasing of degradation. Soil erosion modulus of moderate, severe and extreme degraded meadows were 2.0, 3.0, 4.6 times of slightly degraded meadow, and the coefficients of variation were 21%, 57% and 44%, respectively. Soil field capacity decreased with increased alpine meadow degradation, while soil field capacities of severe and extreme degraded meadows were lower than the lightly degraded meadows 23.9% and 29.9%.

Key words: Alpine meadow, Grassland degradation, Soil erosion, Physicochemical characteristics

摘要： 以三江源地区高寒草甸退化坡面为研究对象,揭示坡面草甸退化梯度所处不同位置下土壤侵蚀和土壤理化性质的变化规律,对明晰坡面草地因人为载畜破坏发生退化后,自然侵蚀作用对土壤理化性质的变化具有重要意义。结果表明:高寒草甸土壤有机质和全氮在坡面上与¹³⁷Cs比活度呈现基本一致的分布规律,表现为轻度退化与中度退化差异较小,中度退化显著高于重度退化,极度退化高于重度退化的分布特征(P<0.05);随退化程度加剧,土壤有机质和全氮呈现下降的基本规律,并且高寒草甸坡面土壤有机质和全氮在不同草地退化程度下具有不同的坡面运移特征;高寒草甸坡面土壤有机质、全氮含量因退化梯度表现出显著差异(P<0.05),高寒草甸退化坡面土壤侵蚀模数随退化梯度增加而递增,相应的土壤田间持水量表现为随退化梯度增加而降低。

关键词: 高寒草甸, 草地退化, 土壤侵蚀, 理化特征