Fig. 4From: Variations in the natural 13C and 15N abundance of plants and soils under long-term N addition and precipitation reduction: interpretation of C and N dynamicsEffects of N addition, precipitation reduction and their combination on N return proportion (%) in different tree species. PKS: Pinus koraiensis; TAR: Tilia amurensis; and FMR: Fraxinus mandshurica. Error bars represent 1 SE of the meanBack to article page