Objective The aim this study was to explore the distribution patterns and limitation of nutrient elements in subtropical forest species in southern Yunnan, for revealing the adaptive mechanism of tree species under a changing environment.

Method The dominant species in three types of tropical forests, i.e., tropical seasonal rain forests, tropical montane rain forests and montane moist evergreen broad-leaved forests, were sampled in southern Yunnan to analyze C, N, P and their stoichiometric ratios in sapling stems.

Result 1) The total C of sapling stems of dominant species in the three types of tropical forests generally increased, but total N and P decreased with increasing elevation. 2) The ratios of stem C:N and C:P in montane moist evergreen broad-leaved forests were relatively high compared to other two types of forests. The ratio of stem N:P both in tropical seasonal rain forests and tropical montane rain forests were less than 14, while this value in montane moist evergreen broad-leaved forests was higher than 16. 3) The stem C and N of dominant species in upper canopy were smaller than lower canopy. However, total P contents in upper canopy was higher than those in lower canopy. The value of N:P in upper canopy was less than 14, whereas it was higher than 16 in lower canopy. These results suggested that the growth of dominant species in upper canopy was mainly limited by N. 4) The results of Redundancy analysis revealed that elevation and community had a great effect on C, N and P contents and their stoichiometric ratios in sapling stems of dominant species.

Conclusion Montane moist evergreen broad-leaved forest has a relatively high nutrient efficiency, and the forest ecosystems in southern Yunnan are mainly limited by N and P contents. The difference of ecological stoichiometric characteristics in trees under different environments can reveal the coping mechanisms of species adaptating to changing environments.