A Comparasion Of The Forest Community Structure Between Daliangshan And Xiaoliangshan Of Sichuan

This paper analysed the influence of geographical factors on forest community distribution in Da-liang Mountains and Xiao-liang Mountains. Surveys of community construction of forests in Mabian in Xiao-liang Moutains and Ganluo and Yuexi in Da-liang moutains were conducted in April, June and July 2001, June and November 2005. 488 forest quadrats of 20×20 m~2 and 914 bamboo quadrats of 1×1 m~2 were sampled, including 257 forest quadrats and 457 bamboo quadrats in Ganluo and Yuexi and 231 forest quadrats and 457 bamboo quadrats in Mabian.Species important index, Shannon—Wiener index and Pielou evenness index have been computed considering the diversity of species in both places. At last, the spatial patterns of forest communities at both places were show in the graphic. Diversity of species in forest community of Mabian is higher than in Ganluo and Yuexi. Based on the results of diversity of species at both places, Twinspan was used to classify both forest communities. The detrended canonical correspondence analysis (DCCA) was used to ordination analysis for dominant species and eight topography factors (elevation, latitude, longitude, position, slop shape, slop exposure, slop, topographical index) that determine community distribution.The results show: 1) There are 21 families, 38 genera and 70 species in Ganluo and Yuexi, 6 species in 3 genera are baboons; there are 20 families, 39 genera and 74 species in Mabian, 11 species in 5 genera are baboons. 2) There are 68 different kinds of forest communities in Ganluo and Yuexi, including 21 needle leaf communities and 47 broad leaf communities, there are 87 different kinds of forest communities in Mabian, including 16 needle leaf communities and 71 broad leaf communities. Both species and community diversities are higher in Mabian than in Ganluo and Yuexi. 3) Altitude is the crucial factor that influences the distribution of forest communities in Da-liang Mountains and Xiao-liang Mountains. 4) The influence of position on community ditribution is strong in Ganluo and Yuexi, while the influence of slop shape on community ditribution is strong in Mabian. 5) Position and slop shape influence the distribution of forest communities through geographical processes, such as moisture preventing and soil accumulation.