Correlations (r) between foliar elements and ratios of C3 species sampled from 82 sites on the Qinghai-Tibet Plateau, China.

∑K+ Ca+ Mg, sum of the K, Ca and Mg concentrations in leaves. C/N, the ratio of foliar C concentration to N concentration; C/P, the ratio of foliar C concentration to P concentration; N/P, the ratio of foliar N concentration to P concentration.“−”correlation rejected because of functional connection; ***, P**, P*, P