A study of soil moisture migration mechanism of alpine meadow in the Tibetan Plateau

The alpine meadow soil water for sustaining the succession of vegetation ecosystem benign role lies in finding out the alpine meadow area soil moisture migration mechanism, the correct understanding of alpine meadow soil moisture migration process; the improvement of the reconstruction efficiency has important guiding significance. In this paper, based on in situ test of soil profile negative pressure and ground temperature observation, combined with meteorological data, the authors analyzed soil profile temperature, moisture content and total head characteristics. The results show that the freezing period begins in October, and the thawing period begins in April. At the highest temperature, the plant growth period is in August, and the lowest value appears in January. Soil moisture is solid from January 1 to March; from June to October soil water is liquid, belonging to stable phase change; from April to May and from November to December soil moisture is in solid and liquid state, and the moisture content change is bigger, belonging to the excessive stage. With the increase of temperature and the precipitation, the same season in June and August is favorable for the growth of alpine meadow, which belongs to the main growth stage of alpine meadow. In spring, the soil is thawed at the surface and the depth, and the stagnant water performance of the frozen soil ensures the moisture demand of the spring drought and herbage growth. In the late autumn season, the surface and deep soil are frozen, and the moisture content of the deep soil water with the water vapor in the soil protects the moisture demand of the grass growing. This is one of the reasons that the plateau ecosystem can be stable.