Identifying ecological degradation and restoration zone based on ecosystem quality: A case study of Yangtze River Delta

Approximately 60% of the world's ecosystems are in a degraded and unsustainable state, drawing significant attention to the issue of ecological degradation. Diagnosing the scope and extent of ecological degradation is important to enhance the efficiency of restoration. Ecosystem quality was used to identify ecological degradation of Yangtze River Delta (YRD) in this study, which was constructed on three dimensions: ecosystem structure, stability, and services. Sequential t-test analysis of regime shifts were utilized to assess the spatiotemporal changes in ecological quality over 2000–2020 in both raster and townships level. The results showed that ecological quality has remained stable since 2000, but 21% of YRD's total area was degraded. Ecological degradation was concentrated in the coastal and riverine regions. Central and southern parts of Jiangsu and Jinhua City, Zhejiang Province also underwent ecological degradation. Considering that the ecological degradation types of degraded townships within the same watershed were similar, the ecological degradation zones were divided into 10 ecological restoration zones based on watershed and administrative boundaries. The findings offer guidance for green ecological integration and sustainable development of the YRD; and the scientific methods devised here for ecological degradation assessment and restoration zoning are applicable to other regions.