Abstract:In order to explore the influence mechanism of environmental factors on species diversity and functional diversity of different community levels (arbor, shrub and herb) as well as the relationship between environmental factors and community construction, we investigated the distribution of species and measured plant height and leaf area of all species based on the field investigation, and then calculated five diversity indices (i.e., the species diversity, species evenness, functional diversity, functional evenness, functional dispersion) of different community levels which belong to two typical forests in Shanxi Province in northern China. The results indicated that: (1) the species of larch birch mixed forest distributed more uniform, and its species diversity and functional diversity (the arbor layer) were significantly higher than that in the Quercus wutaishanica forest. (2) Compared with the Q. wutaishanica forest, the functional evenness and dispersion of the arbor layer on larch birch mixed forest was significantly greater, while the functional evenness and dispersion of shrub and herb layer on larch birch mixed forest were lower than those of shrub and herb layers on the Q. wutaishanica forest. (3) SD was positively correlated with FD, there were differences between the influence of the environmental factors on species distribution and the influence of the environmental factors on function distribution, which the species distribution was related to the comprehensive influence of the environmental factors and the latter was related to the standalone influence of a particular environment factor. The explanatory of environmental factors was influenced by forest types and community levels. (4) SD of the arbor layer was mainly affected by soil pH, canopy structure (MLA, openness) and PPFD total under, which of the shrub layer was closely related to soil pH and MLA and of the herb layer was influenced by PPFD total under, soil nutrients (SOC and STN) and relative soil water content. While, canopy structure (MLA, openness) was the main environmental factor affecting FD of the arbor layer, soil pH and slope position significantly influenced FD of the shrub layer in the Larch birch forest and the Q. wutaishanica forest respectively, which of the herb layer were mainly affected by LAI and relative soil water content. As such, the results showed that different community levels had different competitive resources in vertical stratification of forest and the arbor layer can limit the distribution of species and traits by changing the canopy structure and affecting understory microenvironment. This study would provide some theoretical support for the study of how environment influence on species diversity and functional diversity and how to develop more scientific forest ecosystem management.