Assessment of the impact of the Poplar Ecological Retreat Project on water conservation in the Dongting Lake wetland region using the InVEST model

The Poplar Ecological Retreat (PER) project is a significant environmental protection initiative implemented to protect the Dongting Lake wetlands ecosystem in China, and the ecological impacts of this project have gradually become a hot topic. In this study, water conservation was selected as an indicator of ecosystem function to explore the impact of the project by using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and geographic statistical methods. Water yield and land-use changes were quantitatively evaluated, and significant changes in the wetland landscape configuration occurred after the PER project because forest beach, moss marshland and mudflat areas were transformed into a poplar-retreat area. Thus, the proportion of the poplar-retreat area and average water yield increased. By using the principal component and cluster analysis methods, climate change and landscape patterns were shown to be the dominant driving factors affecting water conservation under stable meteorological conditions. Moreover, the landscape heterogeneity that resulted from the landscape patterns had a greater impact than climate change, which means that reducing human activities can enhance water conservation. Additionally, the correlation between landscape heterogeneity and water yield indicated that reducing landscape fragmentation and improving aggregation also benefit water conservation. Therefore, the PER project is successful at enhancing ecological functions and protecting wetland environments, and it represents a good example of maintaining ecological sustainability despite local economic performance restrictions. This project serves as an important reference for the establishment of sustainable wetland ecological policies by national governments, and the results can provide theoretical support for landscape ecology and eco-hydrology research.