A novel wetland ecological quality index (WEQI) for rapid assessment of permafrost-dominated wetlands in Northeast China from 2001 to 2020

Wetlands in the permafrost regions of Northeast China, critical ecosystems maintained by a strong permafrost-wetland coupling, face significant threats from climate warming and anthropogenic pressures. However, conventional ecological assessment methods often overlook the unique influence of permafrost as a habitat factor and lack the capability for rapid, continuous monitoring over large areas. To address this limitation, this study developed the Wetland Ecological Quality Index (WEQI), a novel framework for assessing the spatiotemporal dynamics of wetland ecological quality from 2001 to 2020. The WEQI is constructed by integrating multiple variables: four remote sensing-derived indicators, namely wetness (MNDWI), vegetation abundance (FVC), and soil moisture (Tasseled Cap Transformation), combined with topographical data (DEM). We employed the Geodetector model to identify the primary drivers of these changes across different permafrost zones. Our results indicate that wetland patches, while remaining somewhat connected, were developing more complex and irregular shapes, the overall ecological quality paradoxically showed a slight improvement over the past two decades. This trend was corroborated by assessments using the InVEST model. Driving factor analysis indicates that in different permafrost regions, the combined influence of ground temperature and other factors is more pronounced. The proposed WEQI provides an effective tool for the dynamic assessment and monitoring of wetland ecosystems in high-latitude cold regions. It offers a scientific basis and new insights for the sustainable management, conservation, and restoration of these vulnerable ecosystems.