[Spatiotemporal Variation Characteristics and Driving Factors of Vegetation NPP in the Yangtze River Delta from 2000 to 2022].

The Yangtze River Delta Region is one of China's most open， innovative， and economically active regions， and understanding the spatiotemporal variation characteristics and driving factors of its net primary productivity （NPP） plays an important role in revealing the status of vegetation restoration and guiding ecological restoration. Based on the MODIS NDVI remote sensing dataset and meteorological data， the NPP data in the Yangtze River Delta from 2000 to 2022 were estimated by using the carbon flux model of terrestrial ecosystem. In addition， the temporal and spatial variation characteristics and stability of NPP in the study area were estimated by using Theil-Sen Median trend analysis， the Mann-Kendall significance test， and the coefficient of variation method. Using partial derivative analysis， the contributions of climate factors and human activities to NPP change in this region were quantitatively revealed， and the driving factors of NPP change were analyzed. The results follow： ① The vegetation net primary productivity （NPP） in the Yangtze River Delta Region showed a fluctuating upward trend， with a rate of 3.62 g·m^-2， from 2000 to 2022. ② The average vegetation NPP exhibited pronounced spatial differentiation characteristics， typically exhibiting a spatial distribution pattern of high in the south and low in the north and high in the west and low in the east. In the past 23 years， the vegetation NPP changed with a significant increase trend， which accounted for 48.15% of the total area of the study area. ③ During the study period， the NPP of vegetation in the Yangtze River Delta was dominated by low fluctuation and medium fluctuation， accounting for 51.83 and 30.36% of the total area of the study area， respectively. ④ The contribution of climate change to vegetation NPP changes in the Yangtze River Delta Region was greater than that of human activities， which had a more significant negative impact. ⑤ The driving mechanism analysis showed that the vegetation NPP changes in the Yangtze River Delta Region were largely attributable to the decrease due to the influence of human activities.