关键词: 若尔盖高原, 草甸退化, 高寒土壤, 可溶性有机碳

Abstract: Study on the response of soil dissolved organic matter (DOM) to alpine meadow degradation is helpful to provide basic data and theoretical basis for ecological restoration and carbon sink function improvement of degraded alpine meadow system. The soil DOM content, structural characteristics and chemical composition in alpine meadows with different degradation degrees (non-degraded meadow, lightly degraded meadow, moderately degraded meadow, heavily degraded meadow) were studied by using space instead of time sampling method and spectrum technology. The results showed that the content and distribution ratio of DOM in the soil of non-degraded meadow were 486.72 mg·kg^-1 and 0.14%, respectively. The content and distribution ratio of DOM in three degraded meadows were significantly lower than those of non-degraded meadow by 55.25%-69.68% and 33.79%-49.66%, respectively. In terms of structural characteristics, meadow degradation leads to a gradual increase in the aromatization degree of soil DOM, while the molecular weight and degree of humification increase first and then decreased, and reached the maximum in moderately degraded meadow. In terms of chemical composition, meadow degradation leads to a gradual decrease in the relative intensity of the absorption peaks of alcohols, phenols and aromatics, while the relative intensity of absorption peaks of polysaccharides and alkynes gradually increased. In summary, the degradation of alpine meadow will lead to the simplification of soil DOM structure and the reduction of stability, increase the loss of soil DOM, affect the stability of soil carbon pool, and increase the risk of soil quality decline.

Key words: Zoige plateau, Meadow degradation, Alpine soil, Dissolved organic carbon