Assessing Post-Disturbance Net Primary Productivity (NPP) Recovery in Vegetation Disturbance Patches on the Northwestern Sichuan Plateau to Inform Sustainable Ecosystem Management

Net primary production (NPP) is a key indicator of the terrestrial carbon cycle, and its response to disturbance and subsequent recovery is important for understanding regional carbon sink dynamics. Conventional region-based statistical approaches have limitations in capturing localized heterogeneous changes. In this study, a typical ecologically fragile region on the northwestern Sichuan Plateau was selected as the study area. Using the Google Earth Engine (GEE) platform, Landsat time-series imagery (2001–2020) and MOD17A3HGF NPP data were integrated. The LandTrendr algorithm was applied to identify vegetation disturbance patches, and two representative disturbance years (2008 and 2014) were selected for long-term analysis. Trend analysis, coefficient of variation, and the Hurst exponent were used to characterize the spatiotemporal dynamics and stability of NPP in disturbed areas. The results show that: (1) NPP declined after disturbance and then exhibited a recovery trend, with significant spatial heterogeneity in recovery rates; (2) recovery trajectories differed between disturbance years, indicating combined effects of disturbance intensity and environmental conditions; and (3) Hurst exponent analysis suggests that although recovery trends are persistent in most areas, some disturbed patches show potential instability. This study establishes an analytical framework integrating disturbance detection and recovery tracking, which improves the representation of NPP dynamics in heterogeneous regions and provides a basis for assessing ecosystem recovery and carbon sink dynamics.