Abstract: Phylogeny greatly affects plant functional traits. It is still unclear whether leaf carbon content, leaf traits and their plasticity of alpine meadow plants are influenced by their genetic background. We measured foliar carbon content, specific leaf area and their plasticity of 12 dominant plants in alpine meadow ecosystems under soil nitrogen and phosphorus heterogeneous conditions and analyzed their differences at species and family levels and their phylogenetic conservatism. The results showed that, at species and family levels, foliar carbon contents and specific leaf area were significantly different (P<0.05) at different soil nitrogen conditions. The difference of carbon content was not significant under different soil phosphorus conditions, but the specific leaf area had significant difference (P<0.05). There was no correlation between foliar carbon content and specific leaf area, but their plasticity was positively correlated, indicating that the two traits of different species had similar response to variation of soil nitrogen and phosphorus. Meanwhile, no significant phylogenetic signal was detected in foliar carbon content, specific leaf area and their plasticity, suggesting that those traits and their plasticity were more affected by environmental changes than by their genetic background. This study is helpful to understand the process of carbon cycling in alpine meadow under the global change background, and would provide scientific basis for the restoration and management of degraded alpine meadow.

Key words: slope aspect, tree-ring, altitude gradient, Pinus massoniana, climate change.