Contrasting productivity–oxygen co-variation in natural and human-influenced areas of the Qinghai–Tibetan Plateau

Vegetation plays a fundamental role in the terrestrial carbon-oxygen cycle, with gross primary productivity (GPP) coupled to biospheric O₂ release. Ongoing warming and increasing human activity may perturb this coupling by altering productivity, respiration, and land-surface processes. These effects are of particular concern on the Qinghai–Tibetan Plateau, where such high-elevation regions are highly sensitive to climatic forcing and anthropogenic changes. As a proxy for O2 exchange, near-surface relative oxygen concentration (ROC) reflects the combined effects of biogeochemical processes, anthropogenic activities, and atmospheric transport. Here, we integrate satellite-derived GPP estimates, reanalysis meteorological data, and land-cover classifications to quantify the variability of GPP and ROC across the Qinghai–Tibetan Plateau from 2001 to 2024. We find clear land-use-dependent patterns in the co-variation of GPP and ROC. In natural ecosystems such as grasslands and forests, GPP and ROC increase synchronously, whereas in built-up areas both GPP and ROC decrease. We also find that near-surface air temperature increases across all land-use classes and is strongly correlated with GPP and ROC variability in natural ecosystems. Overall, our results suggest that intensifying human activity simultaneously increase oxygen consumption and reduce the biospheric contribution to O₂ production by constraining vegetation productivity. These patterns provide observational evidence of increasingly challenging conditions for livestock in high-elevation regions and of weakened ecosystem functioning under growing human impacts.