Mechanisms of meteorological drought impacts on desert steppe ecosystem productivity in Inner Mongolia, China

Understanding desert steppe ecosystem productivity and its response to meteorological drought is crucial for global carbon cycling research. This study evaluated the vegetation productivity of the desert steppe at the northern foothills of the Yinshan Mountains from 2001 to 2021 based on MODIS GPP, NPP, and NEP estimation model. By combining these metrics with the Standardized Precipitation Index (SPI), it explores the spatiotemporal dynamics of productivity and drought legacy effects during the growing seasons (May-September). Results show that the carbon flux components exhibited notable enhancement, with annual mean values reaching 190.1 gC·m^-2·a^-1 for GPP, 124.1 gC·m^-2·a^-1 for NPP, and 83.1 gC·m^-2·a^-1 for NEP, all showing significant increasing trends (p < 0.05) and distinct spatial gradients from southeast to northwest. Precipitation emerged as the dominant control factor, with variability explaining about 83 % of productivity fluctuations, supported by strong correlations. SPI analysis showed mild droughts occurring 25.7 % of the time, increasing in severity west-to-east. Drought legacy effects lasted up to 3-5 months (typically 3 months), with lagged responses peaking at 1-2 months (most significant at 1 month). These findings enhance understanding of carbon-climate feedback in arid regions and inform steppe management and drought mitigation strategies under climate change.