Shifting pathways of post-earthquake vegetation structural and functional recovery under varying earthquake disturbance intensities

Extreme disturbances (e.g. earthquakes) alter ecosystem structure and function, and shape the patterns of ecosystem resilience and carbon sink recovery. Spatial heterogeneities in varying seismic intensities may drive divergent structural and functional recovery trajectories, yet the synchrony between the two recoveries remains unclear. Moreover, the inadequate evaluation of satellite-derived biophysical products, along with the effects of climate change and human activities, may bias the interpretation of earthquake-induced vegetation recovery trajectories. Taking the 2017 Jiuzhaigou earthquake as a case study, we developed the dual-dimensional recovery assessment framework that integrated the leaf area index (LAI, proxy of structure) and gross primary productivity (GPP, proxy of function). The multiple GPP and LAI products were separately evaluated using eddy covariance observations and high-resolution reference data to select the representative vegetation structure and function proxies. The vegetation damaged areas (VDA) were then extracted using joint GPP–LAI thresholds. Subsequently, the residual analysis was served isolate the effects of climate change and human activities, as well as to quantify the impacts of earthquake disturbances on vegetation recovery during 2018–2023. The results indicated that PML-V2 GPP and MODIS LAI exhibited relatively high stability, and 56.52% of the area experienced concurrent structural and functional damage, with the earthquake disturbance contributing approximately 75% to the VDA. Early post-earthquake structural and functional recovery showed pronounced asynchrony but gradually became coordinated over time. Distinct recovery pathways of vegetation structure and function were observed across disturbance intensity zones. Specifically, in severely disturbed zones, the GPP recovered faster than LAI, which implied that functional recovery outpaced structural recovery (i.e. the function-leading recovery pathway). In contrast, the opposite pattern was observed in the moderately and weakly disturbed zones, where structural recovery preceded functional recovery (i.e. the structure-dominated pathway). The variation in leaf photosynthetic efficiency partly explained the divergent recovery dynamics between LAI and GPP under different earthquake disturbance intensities. By 2023, more than half of the area remained degraded or in ongoing recovery, which highlighted the long-term and spatially heterogeneous nature of ecosystem recovery. Our study reveals distinct post-earthquake vegetation recovery pathways from an integrated structure–function perspective. These findings provide important insights into the spatiotemporal dynamics of vegetation recovery and its implications for regional carbon cycling.