Abstract:Samplings were gathered and examined in forests along topographical gradients of Mengshan Mountain, China in July of 2007 and 2008. The major communities in the forests can be classified as Quercus acutissima, Pinus densiflora, Pinus tabuliformis, Larix kaempferi, Pinus thunbergii and Robinia pseudoacacia-Q.acutissima community. Our research suggests that the Quercus acutissima community appears to be a dominant community in a successional stage toward temperate deciduous broad-leaved forests. The species richness in different layers of these communities can be distinguished as, herb layer>shrub layer>tree layer. Both the Shannon-Wiener diversity index and Simpson diversity index were found as shrub layer>herb layer>tree layer. The species diversity indices of different layers and overall importance value of the forest communities indicate that the forests appear to be successional and sub-climax communities in Mengshan Mountain. Our research also suggests that there is a peak with higher species diversity index in the communities of middle elevation. We found that the pattern could be affected by temperature, moisture, and human disturbance. The pattern could also be influenced by the nature of successional stages and sub-climax communities, or it could simply be due to the limitation in our sampling area and extend of gradients (800 m).