Aim Community-level biomass-to-nutrient ratios and elemental stoichiometry of forests can provide insights for understanding the efficiency of nutrient use and the adaptation strategies of trees. However, the global-scale pattern of biomass:N:K:Ca:Mg:P ratios in forest stands and its responses to environmental drivers remain unknown. Location World-wide. Time period 1959-2015. Major taxa studied Trees in forests. Methods We synthesized data from 356 forests distributed globally to study the biogeographical variations in biomass-to-nutrient ratios and elemental stoichiometry. Results Our results revealed that the biomass:N, biomass:P, biomass:K, biomass:Ca and biomass:Mg ratios of living trees in forests averaged 330.2 +/- 11.1, 3847.1 +/- 164.6, 615.3 +/- 26.1, 393.2 +/- 15.0 and 2221.5 +/- 92.0, respectively. The biomass:N, biomass:K, biomass:Mg, P:K, P:Mg and Ca:Mg ratios decreased with mean annual temperature and increased from low to high latitude, whereas the N:P and K:Ca ratios displayed the opposite trends. The biomass:P, N:P and K:Ca ratios increased significantly with increasing mean annual precipitation (MAP), whereas the P:K, P:Mg and Ca:Mg ratios decreased with the MAP. The biomass:N and biomass:Ca ratios decreased significantly with increasing soil N and Ca stocks, respectively. Forest stand age significantly affected biomass-to-nutrient ratios, with the older forests displaying higher biomass:N and biomass:P. The scaling relationships indicated that, on average, as biomass increased, biomass:N would increase, because N rose more slowly than linearly with biomass, whereas the Ca and Mg increased proportionally with biomass. Main conclusions Our findings proved that the community-level biomass-to-nutrient ratios and stoichiometry were affected by climate, soil, stand age and taxonomy of trees.