High coupling but low coordination: Climate–vegetation interactions on the Chinese Loess Plateau under rapid greening

In arid and semi-arid regions, large-scale vegetation restoration is widely implemented to combat land degradation. However, it remains unclear whether human-induced greening is synchronized with climate dynamics for long-term sustainability. The Chinese Loess Plateau, a major ecological restoration region, provides an ideal case study. Using a coupling coordination degree model and multi-source datasets from 1990 to 2020, this study investigated the spatiotemporal interactions between climate and vegetation. Results showed a significant warming–wetting trend accompanied by substantial greening and increased carbon storage. A clear mismatch emerged: the system exhibited high coupling but low coordination (coupling degree >0.80, coordination index <0.15), indicating persistent mild maladjustment (coupling coordination degree <0.35). This suggests a potential systemic risk in dryland restoration, where anthropogenically driven vegetation expansion may outpace climatic feedback. The dominant driver shifted from natural productivity to land-use change and, more recently, to precipitation constraints. These results indicate that water availability is a key constraint on greening and that increased vegetation cover does not necessarily ensure sustainability. Therefore, ecological restoration policies may need to shift from a greening-oriented approach toward a comprehensive assessment-oriented framework, taking into account restoration quality in hotspot areas, ecosystem stability in not significant areas, and hydroclimatic suitability in cold spot areas to support the long-term sustainability of regional ecological restoration.