Evaluation of the impact of ecological poplar retreat on the net primary productivity of Lake Wetland

Abstract

The Poplar Ecological Retreat Project (PERP) serves as a crucial ecological restoration measure for international wetland conservation. Assessing the impact of PERP on the Net Primary Productivity (NPP) of wetlands is essential in elucidating the mechanisms behind anthropogenic environmental effects and evaluating the ecological benefits derived from resource utilization. The PERP implemented in Dongting Lake wetland represents an exemplary ecological project aimed at restoring lake wetland habitats. In this study, we employed the Carnegie-Ames-Stanford approach (CASA) model and remote sensing techniques to investigate the spatiotemporal evolution of NPP and its driving factors pre- and post-PERP implementation. Our findings revealed that: (1) PERP significantly altered the composition structure of wetland cover in Dongting Lake, primarily due to reed and mudflat conversions, resulting in a substantial increase in Poplar-retreat area to 13,895.3 ha; (2) Implementation of PERP led to a significant decline in NPP within poplar plantation areas, with regional NPP experiencing a decrease by 63.91 %. It was predominantly driven by shifts in NPP within reed beaches, forest beaches, and moss marshlands; (3) The analysis on driving contributions to NPP changes demonstrated that landscape pattern elements (41.47 %) > climate elements (30.29 %) > vegetation cover element (8.31 %), while marginal effects on NPP indicated that increased rainfall, evapotranspiration, patch diversity, and aggregation weakened its marginal effect whereas elevated temperature strengthened it instead. The study provided an important reference for revealing the carbon sink mechanism of the human-land coupling of wetland landscapes.