Tree species is the major factor explaining C:N ratios in European forest soils

•C:N ratio in forest floor, peat and mineral topsoil mainly depend on tree species.•Most important differences in C:N ratios are seen between deciduous and evergreen species.•Either soil type, ecoregion or humus type was the second most important explanatory factor.•There was no consistent relationship between modelled deposition and C:N ratios.