Spatiotemporal evolution and coupling of “Forest–Cropland–Water” ecosystem vulnerability in the Yangtze River Economic Belt

The Yangtze River Economic Belt (YREB), China's "golden waterway" and "green barrier", relies on its "Forest-Cropland-Water" system for carbon sequestration, grain production, and water conservation. Tracking its vulnerability and coordination on a spatiotemporal scale reveals barriers to balancing ecological security with sustainable growth. Our study innovatively proposes a multi-system coupling evaluation framework. We integrate the Order relation (G1) method, the CRiteria Importance Through Intercriteria Correlation (CRITIC) method, and a game theory combination weighting to assess the ecological vulnerability of the "Forest-Cropland-Water" system across YREB. Using coupling coordination and spatial autocorrelation models, we then map the spatiotemporal pattern and spatial clustering characteristics of ecosystems interactions. Finally, geodetector method is employed to identify the principal drivers of coupling coordination. In 2000-2023, the ecological vulnerability of each ecosystem and the overall system exhibited a fluctuating downward trend. Spatial clustering of coupling coordination gradually weakened, and coupling types shifted from mild imbalance toward mild coordination. Concurrently, high vulnerability areas progressively transitioned to moderate and low vulnerability. Among the driving factors, Land use intensity and aerosol optical depth consistently exhibited the strongest explanatory power for the coupling coordination degree of the "Forest-Cropland-Water" system, whereas the influence of extreme high-temperature days markedly declined over time and the remaining selected factors played only subsidiary roles. This work provides a systematic framework for assessing future multi-system ecological vulnerability and coupling relationship, offering scientific guidance for promoting sustainable natural-resource management and inter-basin development.