Analysis of spatial and temporal distribution of grassland yield under grassland ecological subsidy policy

The Three River Headwater Region is an ecologically sensitive and fragile area. The analysis of long-term grassland yield changes, as well as the impact of climate and topography on grassland yield is of great significance to grassland ecological protection and the implementation of ecological subsidy policy in the Three River Headwater Region. Based on the grassland yield data from 2011 to 2016, this paper analyzed the spatial and temporal distribution of grassland yield and variations in grass production since the implementation of the grassland ecological subsidy policy in Qinghai Province by using linear regression analysis, coefficient of variation, and biased correlation analysis. Additionally, the effects of three meteorological factors, namely, annual mean temperature, annual precipitation, and annual evapotranspiration, and two terrain factors, namely, elevation and slope, on grassland yield were analyzed. The results were as follows: (1) The grassland yield in the Three River Headwater Region gradually decreased from east to west; From the classification space of grassland, it can be seen that with the alpine meadow as the boundary, the spatial distribution of grassland yield in the Three River Headwater Region forms an obvious watershed. (2) The overall grassland yield in the Three River Headwater Region increased first and then decreased, but the overall change trend was not large. (3) The positive correlation between the average annual grassland yield and the average annual precipitation in the Three River Headwater Region was nearly 58%, which was distributed in concentrated contiguous areas, and the eastern and northwestern parts of Three River Headwater Region were more concentrated; The area of positive correlation with annual mean temperature is nearly 48%. The positive correlation between the area and the annual average evapotranspiration is nearly 48%. (4) The grassland yield in the source area of Three River Headwater Region increased first and then decreased with the increase of elevation; The grassland yield increased with the increase of slope. In summary, since the grassland ecological reward policy has been carried out in Qinghai Province, the grassland yield in the Three River Headwater Region has been relatively stable in time and space, positively correlated with precipitation, insignificantly correlated with temperature and evapotranspiration, and highly correlated with elevation and slope.