Decoupling characteristics of county-level land use carbon emissions and ecological environment quality at spatiotemporal scales: a case study of Shaanxi Province, China

A critical approach to achieving dual carbon targets is to maintain strong decoupling (SD) between land use carbon emissions (LUCE) and ecological environment quality (EEQ). However, the spatiotemporal decoupling mechanisms of LUCE and EEQ at the county scale remain understudied. This study aims to explore the decoupling dynamics of LUCE and EEQ across 107 counties in Shaanxi Province from 2000 to 2020. Using the PIE-Engine and Google Earth Engine, we constructed LUCE and Remote Sensing Ecological Index (RSEI) models and applied the Tapio decoupling theory to analyze the decoupling trends. The results reveal that from 2000 to 2020, LUCE in Shaanxi tripled, while EEQ increased by 20.93%, albeit with fluctuations. County-level variations in LUCE and EEQ exhibited pronounced spatiotemporal heterogeneity, with decoupling types undergoing significant transitions in over 95% of counties. In 2005, 28.04% of counties achieved a decoupled state, but this deteriorated sharply by 2020, when nearly half of the counties displayed strong negative decoupling (SND), and no counties maintained SD. These findings suggest that achieving SD remains challenging and requires targeted strategies based on regional decoupling characteristics. This study offers a theoretical and practical framework for understanding county-level LUCE and EEQ decoupling, which is crucial for sustainable development.