Correlation between leaf δ¹³C and leaf N_mass for different vegetation types.

a: evergreen broad-leaved forests; b:coniferous and broad-leaved mixed forests; c:frigid dark coniferous forests; d:alpine sub-frigid shrub and meadow vegetation; and e:alpine frigid meadow vegetation. Solid lines indicate the linear regressions of δ¹³C vs. N_mass.