Impacts of cascade dam construction on riparian vegetation in an alpine region

Abstract

The Jinsha River (JSR) serves as a crucial ecological corridor in the upper Yangtze River Basin, hosting one of the world’s largest cascade hydropower dam (CHD) developments. However, systematic quantitative research on riparian vegetation (RV) ecosystems along JSR response to CHD construction and climate change is lacking. Using multi-source datasets from 2000 to 2022, we quantified the effects of CHD on key climatic factors (temperature, precipitation, vapor pressure deficit, and soil moisture) and analyzed their contributions to RV dynamics. Results indicate that RV in the JSR exhibited a more pronounced “greening” trend after CHD construction (The NDVI trend is rising from 0.0021 yr−1 to 0.0096 yr−1, by more than four times). CHD operations led to decreased temperature and vapor pressure deficit, while increasing precipitation and soil moisture, significantly improving the growth conditions for RV. Structural equation modeling further revealed that CHD not only directly promoted RV growth but also exerted significant positive indirect effects by regulating the regional microclimate. Importantly, the cumulative effects of CHD resulted in a long-term positive impact on RV growth that outweighed the initial short-term negative impacts during construction. This study underscores the importance of integrating hydropower development into long-term riparian ecosystem monitoring and management, providing valuable insights for sustainable river basin management amid global climate change.