Plant Community Diversity And Spatial Differential Rules Of Erman's Birch Forest On The North Slope Of Changbai Mountain

Erman's birch (Betuala errmanii) forest is the most significant type of natural landscape change on Changbai Mountain. The Nature Reserve of Changbai Mountain is the biggest distributive range of erman's birch forest in China, and the distribution of vegetation of Changbai Mountain along an altitudinal gradient is obviously. So Changbai Mountain is the best place for researching the population of Erman's birch. Based on the platform of science and technology which is supplied by the program of International Ecological Security and the Geographical Data Integration of Changbai Mountain, we researched plant community diversity of erman's birch forest. This program belongs to College of Urban and Environmental Science, Northeast Normal University. In this paper, we analyzed the change trend of the spatial differential rules and plant community diversity of erman's birch forest along an altitudinal gradient, used by indexes, such as DBH (diameter at breast high),αdiversity index andβdiversity index. Along the elevational gradient, the DBH of erman's birch is showed by inverted J-curve. The growth pattern of erman's birch is dispersion -type transited by centralized -type from altitude 1650-1750m. From altitude 1750-2000m, the growth pattern of erman's birch is centralized -type. From altitude 2000-2050m, the growth pattern of erman's birch is centralized-type transited by dispersion–type. Species richness in the tree and shrub layers declined with altitude, while herb layer species richness showed no significant trend along the altitudinal gradient. Peak values of tree and herb layers showed that maximum value of species richness is in the transitional belt. With increasing altitude, represented by Simpson index, increased for both tree and shrub layers, with no clear trend for herb layer. Both Shannon-Wiener index and Pielou evenness index in the tree and shrub layers showed downward change with increasing altitude, with no clear trend for herb layer.βdiversity ,indicated by the Cody index , declined with increasing altitude for all three layers. Valley values of tree and herb layers showed that minimum value ofβdiversity is in the transitional belt.