关键词: 极端气候, 净初级生产力, 内蒙古草原, 放牧强度

Abstract: Under the scenarios of climate change and intensified grazing activities, exploring the response characteristics of grasslands to extreme climate in different grazing intensity areas of Inner Mongolia is of great significance for the coordinated development of pastoral economy and healthy ecological environment. Based on net primary productivity (NPP) and meteorological data from 2001 to 2023, we integrated trend analysis, linear correlation analysis, the XGBoost + SHAP framework, and the Hurst index to examine the responses of grassland NPP to climate extremes across different grazing intensity zones in Inner Mongolia. The results showed that: (1) NPP increased significantly at a rate of 3.09 g C·m^-2·a^-1, with the highest increase in heavy grazing zones (4.44 g C·m^-2·a^-1), followed by moderate (3.21 g C·m^-2·a^-1) and light (1.94 g C·m^-2·a^-1) grazing zones. (2) Inner Mongolia grasslands experienced an overall warming and drying trend. Pronounced warming and drying were observed in the light and moderate grazing zones located the southwestern Inner Mongolia, while the heavy grazing zone in the northeastern Inner Mongolia showed a warming and wetting trend. (3) NPP was more sensitive to extreme precipitation than extreme temperature. Extreme precipitation generally had a positive effect on NPP across different grazing intensity zones, without spatial variations. Specifically, the decrease of extreme precipitation inhibited NPP in light and moderate grazing zones, whereas the increase of extreme precipitation promoted NPP in heavy grazing zones. Extreme temperature generally exerted a negative influence on NPP, and the magnitude of this effect increased with grazing intensity. The overall warming across the study region tended to suppress the growth of NPP. (4) Grassland NPP in light and moderate grazing zones may continue to be negatively affected by extreme high temperature and precipitation events. In contrast, future climate conditions in the heavy grazing zone, characterized by a reduction in the extreme low and high temperatures as well as an increase in precipitation events, are likely to enhance grassland NPP. Our findings provide scientific support for pastoral grassland ecological restoration, rational grazing management, and the mitigation of extreme climate impacts.

Key words: climate extreme, net primary productivity, Inner Mongolian grassland, grazing intensity