Analysis of Net Primary Productivity Variation and Quantitative Assessment of Driving Forces--A Case Study of the Yangtze River Basin  
[PERSON]  
1 Electronic Information School, Wuhan University, Wuhan 430072, China; [EMAIL_ADDRESS]. critical indicator of ecosystem productivity [12], and is also more sensitive to factors such as climate and human interference [13]. Consequently, tracking the spatiotemporal dynamics of NPP over historical periods is imperative for forecasting future trends in carbon and ecosystem environmental changes. The change in NPP is closely related to climate change [14; 15]. The combined effects of climate change and other factors may cause irreversible impacts on the ecosystem [16], and moreover have more or lesser effects on vegetation carbon sequestration. Temperature, precipitation, and solar radiation are all key factors influencing vegetation growth. Warming temperatures lead to changes in vegetation phenology, with an earlier onset of spring phenology and a delayed onset of autumn phenology [17; 18; 19]. Additionally, the temperature increase leads to a reduction in the temperature difference between summer and winter, impacting vegetation photosynthesis and altering vegetation productivity [20]. In tropical regions, studies have shown that intra-annual temperature variations lead to more pronounced vegetation periodicity, with temperature changes having a greater impact compared to other climatic variables [21]. The availability of water for vegetation is the foremost factor in ensuring vegetation growth and the degree of vegetation dependence on available water varies significantly [22]. The sensitivity of vegetation productivity to precipitation varies across different regions, with arid regions being more sensitive compared to humid areas, and grasslands and shrublands exhibiting higher sensitivity compared to forests and wetlands [23]. Similarly, extreme rainfall events can increase vegetation net productivity in arid regions while having a negative impact on vegetation in humid areas [24]. Solar radiation is the essential energy source for vegetation growth, and a decrease in solar radiation within a certain range will result in a decline in vegetation productivity [25]. The YRB, Asia's largest river, traverses the vast inland regions of China, encompassing significant wetlands, extensive grasslands, and diverse forest ecosystems. Notable wetlands in the area include the Poyang Lake Wetland, Dongting Lake Wetland, and the Three Gorges Reservoir Wetland. These wetland areas [26] play pivotal roles in ecological equilibrium, serving as crucial habitats for rare wildlife and exerting essential influence on water resource conservation and regulation. Grasslands [27] provide a vital source of sustenance for livestock, contributing significantly to soil erosion mitigation, the promotion of biodiversity, and the preservation of ecological balance. Forests [28] blanket the mountainous and hilly terrains throughout the YRB, fulfilling critical ecological functions such as oxygen generation, soil and water conservation, and carbon cycling. It is not only a valuable ecological barrier [29; 30; 31], but also a significant carbon pool in China's terrestrial ecosystem. Predecessors have carried out a significant amount of research in the YRB, mainly focusing on the vegetation index [32; 33; 34], but there is still a lack of in-depth understanding of the vegetation productivity and its driving mechanisms. [PERSON] et al. [35] conducted research on the impact of NPP from the perspective of land use change. [PERSON] et al. [36] explored the increasing trend and influencing factors of NPP between 2000 and 2014, and the results indicated that human activities were the primary driver of NPP changes. [PERSON] et al. [37] used the LPJ (Lund-Potsdam-Jena) model and NDVI vegetation index to simulate NPP in the YRB from 1982 to 2013.