Remote sensing monitoring of grazing intensity in Zoige Plateau based on aboveground net primary productivity and aboveground biomass

As one of the three grassland pastoral areas in China, the Zoige Plateau is rich in forage resources; however, owing to grazing, the plateau has suffered wetland and grassland degradation and land desertification. The aim of this study was to accurately and quickly estimate the grazing situation in the Zoige Plateau on the regional scale and provide data and theoretical support for the rational organization of human activities and protection of the ecological environment in this area. MODIS-NDVI, ground measured, and meteorological data were used to simulate the aboveground biomass and aboveground net primary productivity (ANPP) and evaluate the grazing intensity in the Zoige Plateau from 2010 to 2019. The model that estimated grazing intensity had a good effect on simulation of actual grazing intensity, with an R² value of 0.7813, and reached an extremely significant correlation level with measured data of grazing intensity (P < 0.05). Moreover, the root mean square error was small and the accuracy reached more than 70%; Thus, this model can distinguish regions with different grazing degrees. The average grazing intensity in the Zoige Plateau in 2019 was 1.87 AU·hm⁻², which is a state of overgrazing, and the overall grazing intensity was higher in the southeast and lower in the northwest. Furthermore, the grazing intensity in the Zoige Plateau showed an overall increasing trend from 2010 to 2019, and increased first and then decreased during 2010−2014 and 2014−2019, respectively, and the distribution of ANPP and aboveground biomass was related to the grazing intensity to a certain extent.