Changes and controls of aboveground net primary production in response to grassland policy in Inner Mongolian grasslands of China

Abstract

Over-reclamation of grassland resources has increasingly contributed to environmental degradation in China. With grassland degradation, actions have been taken to maintain or restore natural grasslands through efforts such as ecological engineering. Inner Mongolia is considered being one of the most severely degraded areas in China and consequently almost all of the national land restoration projects for environmental protection were implemented there, making it the province with the highest investment in environmental restoration programs in China. In this study, we use the estimation model relationship established between the vegetation index extracted from remote sensing images and the measured biomass in the field to inversely calculate the biomass in the study area. And then we focused on the changes in the aboveground net primary productivity (ANPP) of these grassland ecosystems, which is crucial for gaining a better understanding of grassland changes in the light of rapidly changing environmental policies and governance regimes in China. The interannual variation of ANPP fluctuated greatly (fluctuated from 87.81 g/m2 to 88.5234 g/m2 between 2000 and 2017). The grassland changes in the whole region are basically stable, but the changes in individual areas are more serious. The ANPP was negatively correlated with the mean annual temperature and positively correlated with the annual precipitation. The hydrothermal conditions directly affected the distribution and accumulation of ANPP along meadow, typical and desert grasslands. Different stages of grassland policy have different target orientations and have positive and negative impacts on ANPP.