Abstract: In order to study the relevance between vegetation and soil nutrient in the degradation of the mountain meadow at Three River Source region, Qinghai Province, China, analysis of correlation between vegetation characteristics and soil nutrients were carried out on different degraded meadow in Huashi area of Maduo County of Golog Prefecture. The results showed that: in the degradation process, high-quality grass richness and coverage decreased, such as Kobresia pgymaea, while the proportion of low class weed increased, such as Leontopodium alpinum and Artemisia stelleriana. With the aggravation of degraded mountain meadow and increment of soil depth, there were significantly gradient changes for soil organic matter, pH value and available phosphorus. Organic matter decreased significantly. Content of organic matter of non-, mild-, moderate- and severe-degraded meadow were 52.12 g·kg^-1, 36.02 g·kg^-1, 25.54 g·kg^-1, 13.36 g·kg^-1 in top 0-10 cm layers, which had declined to 20.80 g·kg^-1, 25.92 g·kg^-1, 13.67 g·kg^-1, 12.55 g·kg^-1 in the 20-30 cm layers. The soil was alkalized, and soil pH value was 6.88 at non-degraded alpine meadow, while soil pH value was above 8 at moderate- and severe-degradation meadow. The soil pH value increased gradually with the increase of soil depth. Available phosphorus decreased significantly. Content of available phosphorus of non-, mild-, moderate- and severe-degraded meadow were 27.13 mg·kg^-1, 14.12 mg·kg^-1, 9.26 mg·kg^-1, 5.46 mg·kg^-1 at top 0-10 cm layers, while those values had declined to 16.13 mg·kg^-1, 10.88 mg·kg^-1, 1.97 mg·kg^-1, 4.46 mg·kg^-1 at the 10-20 cm layers. There were high correlation between vegetation coverage and available phosphorus, pH and organic matter, and associated value were 0.944 8, -0.979 9, 0.898 2. The two previous data reached significant level. Available P and organic matter are the key factors affecting the growth of vegetation. The innovation and high light of this paper is the discussion about the effect of available phosphorus, pH and organic matter on vegetation coverage and growth.

Key words: Three River Source Region, soil nutrient, vegetation, relevance