Evolution of vegetation dynamics and its response to climate in ecologically fragile regions from 1982 to 2020: A case study of the Three Gorges Reservoir area

The eco-environment in ecologically fragile regions has received increasing concern due to its vulnerability to climate changes. Determination of vegetation dynamics is a prerequisite for sustainable management of eco-environment evolution due to its vital role in regulating earth system and ecosystem services. China′s Three Gorges Reservoir area (TGRA), as a typical ecologically fragile region, was selected to explore its vegetation dynamics and response to local climate in different periods (1982–2020) of GZD-TGD (Gezhou Dam-Three Gorges Dam). The 1982–2020 NDVI dataset was obtained by integrating the overlapping period (2001–2015) of GIMMS NDVI and MODIS NDVI. The results demonstrated that TGRA exhibited a generally greening trend in 1982–2020, and the greening rate increased with the implementation of GZD-TGD, particularly in the last 20 years, which greatly promotes the capacity of vegetation carbon sink. At the annual scale, the mitigation of climate warming occurred with GZD-TGD implementation, particularly after the first impoundment of TGD (−0.0114 ℃yr−1). At the seasonal scale, a certain cooling effect in summer and a warming effect in other seasons (especially in winter) induced by this cascade project were observed, which became more pronounced after the water level reached 175 m. Furthermore, temperature had the most significant positive effect on vegetation dynamics, which increased with GZD-TGD implementation. The driving force of precipitation, VPD (vapor pressure deficit) and sunshine hours was relatively less significant but could not be ignored, with negative contributions from precipitation and VPD and positive contribution from sunshine hours. These findings provide further insights into the effect of climate changes mediated by GZD-TGD on vegetation growth and facilitate the dissection of the complex soil–plant-atmosphere feedback interaction.