关键词: 高寒草甸, 草地退化, 土壤侵蚀, 理化特征

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