Deyang City, situated in a typical mountain-plain transition zone of Southwest China, faces high ecological fragility due to its steep topographic gradient, frequent seismic disturbances (e.g., the 2008 Wenchuan earthquake), and intensive anthropogenic pressures from rapid urbanization and agricultural production. Taking this representative area as a case study, this study utilized multi-source remote sensing data from 2000, 2005, 2010, 2015, and 2020. A comprehensive Land Degradation Index (LDI