A Study On The Plant Community Of Beijing Xishan National Forest Park

Xishan Mountain, located in the north end of Taihang Mountains, reserves a large amount of natural secondary and artificial forest and plays an important role in ecological protection and water conservation in Beijing area. In order to deeply understand the characteristics and stability of plant diversity in Xishan Mountain, this paper analyzed the plant communities in this area from several aspects, including the classification of vegetation types, structural characteristics of main plant communities, variation trend of species diversity, inter-specific association. The main conclusions are as follows.(1) According to the investigation, there are 442 wild vascular plants belonging to 266 genera,82 families in Xishan National Forest Park, among which there are 10 species of ferns, belonging to 7 genera,7 families, and 6 species of gymnosperms, belonging to 6 genera,2 families, and 426 species of angiosperms, belonging to 253 genera,73 families. Based on the dominant species naming principle, plant communities in Xishan Park were classified into 3 vegetation type groups,5 vegetation types,24 formations and 57 associations.(2)Using the important value as a comprehensive quantitative index of species, through the method of sorting, six types of plant communities were selected to represent the main planty community types of typical forest ecosystem in Xishan National Forest Park, i.e. Platycladus orientalis community, Cotinus coggygrias community, Pinus tabulaeformis community, robinia pseudoacacia community, Acer truncatum community, Quercus variabilis community. Based on the analysis of species composition, DBH structure, etc, it is suggested that there are significant differences in species composition, stand density and diameter structure among different plant communities. Artificial forest of Quercus variabilicommunity has the highest stand density of 2135 No./hm2, while artificial forest of robinia pseuddoacaciacommnity has the lowest stand density of 1380No./hm2. The diameter structures of different plant communities show obvious regularity, e.g. normal distribution, approximate inverse "J" shape distribution, the irregular sized double peaks and the obvious single peak positive skew distribution.(3) Species richness and biodiversity of three levels, i.e. tree, shrub and herb, in the six main plant communities were analyzed. The results suggest that the Patrick richness index of three layers rank as follows:herbaceous layer>shrub layer>tree layer, while Shannon-Wiener diversity index, Simpson diversity index, Pielou evenness index ranking shrub layer>herbaceous layer>tree layer.(4)Using ANOVA, chi-square test, and Pearson correlation coefficient test, the inter-specific association of six main plant communities were analyzed with 2×2 contingency table. The chi-square test shows slightly positive association, while Pearson test shows slightly negative association. There is low correlation degree, insignificant negative relationship between these species. Main plant species distribute and use resources reasonably with a relatively independent relationship. The stable value ratios from M. Godron method are far from 20/80, suggesting that the plant communities in Xishan Park have low stability and vulnerable ecosystem, which match the commonly low stability of artificial forestry.The study of forest community characteristics is of vital importance to the management and protection of forest. This paper conducted the study on community characteristics of early planted artificial forest in Beijing Xishan National Forest Park. The results, providing suggests and scientific bases for the construction and management of the park as well forest cultivation, have relatively high theoretical and practical value.