关键词: 青藏高原, 高山草甸, 放牧方式, 土壤水文特性, 土壤特性

Abstract: Alpine meadows of the Qinghai-Tibetan Plateau (QTP) are experiencing severe degradation due to intensified human activity and climate changes. However, there has been little attention paid to the effects of different grazing practices on the soil hydrological properties of alpine meadows. In this study, three grazing practices were established in an alpine Kobresia meadow: free grazing, reduced grazing and grazing exclusion. We found that the 0–10 cm soil water retention capacity (SWR) and plant available water content (AWC) in grazing exclusion treatment were higher than that in reduced or free grazing treatments, whereas the 20–40 cm SWR and AWC display the opposite pattern. The AWC and SWR variations were closely related to soil properties, and the redundancy analysis showed that SWR and AWC were positive related to soil organic matter (SOM), total porosity (TP) and capillary porosity (CP), but were negative correlated with soil bulk density (BD), clay and silt content. Structural equation modeling found that SOM was identified as the most important factor affecting SWR, and CP was the key factor influencing AWC. Therefore, the higher 0–10 cm SWR and AWC in grazing exclusion treatment may be attributed to its higher SOM and CP, respectively. Furthermore, root biomass can affect SWR and AWC through altering BD and SOM. Our study suggests that the response of soil hydrological properties to grazing practices was different, grazing exclusion only increase topsoil water retention capacity but not favor deep soil water retention capacity.

Key words: Qinghai-Tibetan Plateau, alpine meadow, grazing practices, soil hydrological properties, soil properties