Human activities dominated terrestrial productivity increase over the past 22 years in typical arid and semiarid regions of Xinjiang, China

Abstract

Net primary productivity (NPP) reflects the carbon sequestration capacity of terrestrial ecosystems, serving as a crucial indicator of ecosystem health. Arid and semiarid regions, which are ecologically fragile, respond strongly to climate change and human activities, necessitating adequate NPP monitoring. However, large-scale NPP studies for Xinjiang, a typical arid/semiarid region in China, are scarce, and the spatial differentiation of driving forces remains unclear. This study utilized remote sensing data from multiple sensors and meteorological data to invert NPP using the improved CASA model, constructing six scenarios to separate the contributions of climate change and human activities. The results have been verified through measured data and showed a fluctuating upward NPP trend (0.62 gC·m−2·a-1) over the study period, with a multi-year average of 65.86 gC·m−2·a-1. Significant spatial differentiation in NPP was noted, with more variation in oasis areas. Around the rim of Tarim Basin, north Tianshan Mountains, and southeast Xinjiang, NPP significantly increased. Predictions indicated a continuous NPP increase in 43.8% of Xinjiang's area. Significant NPP variations were observed among land use/cover categories and subregions. Human activities predominantly drove NPP increases, while climate change mainly drove decreases. Grassland was more affected by climate change, whereas Cropland was more influenced by human activities. This study accurately captured the spatiotemporal characteristics of NPP in Xinjiang. It explored its drivers, providing a practical method for assessing terrestrial ecosystem NPP and a theoretical basis for sustainable development policies in arid landscapes.