Decoupled greening and vegetation resilience in the arid Tarim River mainstream and its driving mechanisms

Abstract

Vegetation resilience reflects the capacity of ecosystems to withstand and recover from disturbances. However, current research on greenness trends has predominantly focused on changes in vegetation cover or biomass, with limited attention to resilience dynamics and their underlying drivers. Using the arid Tarim River mainstream as a case study, this study quantified vegetation resilience based on the first-order autoregressive coefficient (AR(1)) derived from kNDVI time series during 2000–2020, and identified the environmental drivers of greening and resilience change using random forest models. Results show that the region exhibited significant (p < 0.05) overall greening, yet 51.1% of the area showed a significant (p < 0.05) decline in resilience, and 45.2% of greening areas simultaneously experienced resilience loss, most prominently in the upper and middle reaches. Attribution analysis indicated that greening was dominated by increased surface soil moisture, whereas resilience loss was primarily driven by deep groundwater depletion, with thresholds favorable for greening and resilience maintenance identified as soil moisture trend >0.0005 m3 m−3 yr−1 and groundwater storage anomaly trend > −7.3151 mm yr−1, respectively. Ecological water conveyance improved resilience within the core zones of the lower reaches, but the benefits were spatially constrained, motivating a shift from linear conveyance to spatially distributed delivery with resilience-based zoning and rotational scheduling. Overall, greening does not necessarily imply enhanced resilience, underscoring the value of integrating resilience metrics into future arid ecosystem management.