Severe droughts alter the resistance–recovery tradeoff in northern China’s drylands

Increasing drought intensity under global climate change poses significant threats to the stability of terrestrial vegetation carbon uptake, represented by net primary productivity (NPP), particularly in mid-latitude drylands. The roles of vegetation resistance and recovery to interannual droughts in regulating long-term NPP stability remain poorly understood, thereby limiting predictions of vegetation responses under a changing climate. This study addresses these knowledge gaps by examining dryland ecosystems across the Three-North Shelterbelt region of northern China. Using satellite-derived NPP data (2001–2022), along with land cover data, the standardized precipitation evapotranspiration index (SPEI), and site observations, we characterized spatiotemporal vegetation dynamics and employed extreme gradient boosting (XGBoost) modeling and multiple linear regression to identify key drivers of the resistance–recovery tradeoff and assess how drought intensity influences carbon uptake stability. Our results show that dryland vegetation characterized by high resistance but low recovery maintains greater long-term stability in carbon uptake. The relationship between resistance and recovery was strongly regulated by drought intensity: It was positive under moderate drought, reversed into a negative tradeoff under severe drought, and broke down under extreme drought, indicating a threshold beyond which ecosystem response strategies diverge. Importantly, as drought intensity increased, arid ecosystems showed weakened associations among resistance, recovery, and their interaction, along with a declining sensitivity of carbon uptake stability to these components, indicating possible early warning signals of approaching destabilization. In semi-arid regions, however, the sensitivity of stability increased with drought intensity, partly because the growing dominance of recovery processes helped sustain carbon-uptake stability under stronger climatic stress. These findings underscore the importance of incorporating the mechanisms of coordinated variation between resistance and recovery into assessments of long-term vegetation stability, thereby improving our understanding of carbon uptake stability under prolonged droughts.