Spatiotemporal variation and regulatory mechanisms in carbon budget and resource use efficiencies across global terrestrial biomes

• We quantified spatiotemporal variation and regulatory mechanisms of resource use efficiencies across global terrestrial biomes. • Resource use efficiencies of most ecosystems shows a long-term trend during the observation period. • Resource use efficiencies are mutually reinforcing but mutually constraining between different biomes. Resource use efficiencies (RUEs), including water (WUE), light (LUE), and carbon use efficiency (CUE), are vital indicators of ecosystem functioning. Studying RUEs’ long-term trends and trade-offs is essential for assessing how ecosystems respond to climate change and contribute to carbon sequestration. Based on data from 195 eddy covariance flux sites worldwide, using non-parametric Mann-Kendall Tau-b test, XGBoost and SHAP, this study systematically evaluates: (1) long-term trends and spatial patterns of RUEs across different ecosystems; (2) trade-offs among RUEs; and (3) key factors in regulating RUEs. Results shown that WUE ranged from 1.77 to 3.22 g C kg −1 H 2 O, LUE 0.39 to 1.11 g C MJ −1 and CUE ranged from 0.55 to 0.70. Over time, RUEs showed increased trend in most ecosystems but decreased in evergreen needleleaf forests and OSH ( P < 0.05). In the majority of ecosystems, WUE, LUE, and CUE were positively correlated, while mutually inhibitory in evergreen broadleaf forests, grasslands, savannas, and wetlands. We found that WUE was primarily influenced by gross primary productivity and evapotranspiration. Light use efficiency was affected by photosynthetically active radiation, ecosystem respiration (ER), and vapor pressure deficit. Carbon use efficiency decreased with rising ER but increased with mean annual temperature. We recommend prioritizing the protection and restoration of ecosystems such as deciduous broadleaf forests, mixed forests, and croplands, while improving resource use in evergreen coniferous forests, shrublands, and grasslands, taking full account of RUE trade-offs. Overall, this study enhances understanding of resource utilization strategies and potential ecosystem responses under global warming.