Characteristics of leaf ecological stoichiometry in typical plant communities in karst fault-depression basins of Yunnan Province

Plant community composition, elemental content of plants and stoicheometric characteristics are strongly influenced by geological chemistry, climate and human activities in karst areas. This study is concerned with plants sampled in the natural forest, shrub and grassland communities in a karst fault-depression basin, Mengzi,Yunnan.The purpose is to clarify the content of 12 elements and stoichiometric ratios in leaves of this area. The results show that elemental concentrations of leaves are of an order C > Ca > N > K > Mg > P > Fe > Al > Zn > Mn > Na > Cu, with significant differences in N, K, Ca, Mg, Al, Cu, Zn and Mn concentrations for plants among three communities. P content limits growth of plants in natural forest and shrub communities, and N and P contents separately or jointly affect growth of plants in grassland communities. In grassland communities, ratios C:N, C:Ca and C:Mg of plants are significantly higher, while N:P ratio lower than those in the natural forest and shrub communities.The C:Ca ratio of plants significantly differs among the three communities,with the order of grasslands > natural forests > shrubs. In statistics, 27 pairs of elements (40.9 % of total element pairs) display significant correlations.The results suggest that plants have formed unique ecological stoichiometric traits to adapt for local environmental conditions in karst fault-depression basins of Yunnan.