Abstract: Plant functional traits can help us to deduce plant life history strategies and enhance our understanding to ecosystem functions. In order to study the ecological strategies of adapting environment of 4 Populus species in north slope of the Tianshan Mountains, the differences in functional traits of leaves, stems and roots among Populus alba, P. nigra, P. russkii and P. euphratica were researched. The results show that the leaf size, leaf thickness, leaf dry matter content, stem tegument thickness, wood density and nutrition content of organs were significantly different among the 4 species, but the difference of specific leaf area was not significantly. Among the 4 species, both leaf area and leaf dry matter content of P. alba were the highest, both leaf thickness and wood density of P. euphratica　were the highest, and stem tegument thickness of P. nigra was the highest. Content of N in leaves of the 4 species was higher than that in stems and roots, the difference of N and P contents between stems and roots was not significant, contents of K in leaves, stems and roots of the 4 species were quite different; except P. euphratica, content of P in leaves was higher than that in stems and roots; contents of N, P and K in P. nigra were the highest, but those in P. russkii were the lowest. Variation of the functional traits of the 4 Populus species reflected their adaptation to environment.

Key words: Populus species, plant functional trait, life history, ecological strategies, north slope of the Tianshan Mountains, Xinjiang