Research On Community Characteristics Of Pinus Tabulaeformis Forest In Songshan,Beijing

This research takes the Pinus tabulaeformis forest community in Beijing Songshan National Nature Reserve as the study object.Based on the community study,a comprehensive comparative study of the characteristics of the Pinus tabulaeformis forest community in the area is carried out.We systematically analyze the species composition and structural characteristics of the community and the relationship between the two and the species diversity of the community,and compare the structural characteristics and diversity differences of Pinus tabulaeformis forests of different origins.in order to provide a reasonable basis for the ecological conservation of Pinus tabulaeformis population and the near-natural management of planted forests.Main results as follow:The Pinus tabulaeformis forest community in Beijing is rich in species composition.There are88 vascular species which belonged to families,genera,and the Compositae herb plants have an absolute advantage.Plant family genera have prominent temperate nature.The community has a single dominant tree species,and the species diversity is dominated by the diversity of shrub and herb layers.Compared with the natural forest,the similarity index of the species composition of the planted forest is 71.25%,and there is only a significant difference in the species composition and diversity level of the herb layer(p <0.05).The Pinus tabulaeformis forest community in this area can be divided into three layers of trees,shrubs,and grasses in the vertical direction.The arbor layers in the Pinus tabulaeformis forest communities of different origins are growing well,and the coverage of shrubs and herbs is generally low,especially for the artificial forests on shady slopes,Its shrub layer coverage is less than10%.The tree layer coverage and shrub height of the planted forest community are significantly different from the natural forest(p <0.05),and the growth indicators at other levels are close to the natural forest;most of the natural forests of Pinus tabulaeformis in this area are of middle age by age determination Forest and near mature forest.In different stands of origin,the diameter order distribution of Pinus pinus population was consistent,the diameter order frequency distribution was continuous,and most of the individuals were middle diameter trees within the diameter order range of 8-20 cm,accounting for 76% and 83% of the natural forest and artificial forest respectively.The population development was stable;the tree height distribution of Pinus tabulaeformis var.Mongolica is dominated by individuals of middle-high-level trees,and all higher trees originate from plantations.We conducted a pearson correlation analysis between the alpha diversity index of the Pinus tabulaeformis forest community and various indicators of community composition and structural characteristics in the area,and concluded that the diversity of the shrub layer of the Pinus tabulaeformis forest community in the area was greatly affected by the changes in the community species composition;different origins The diversity index of the shrub-grass layer under Pinus tabulaeformis forest community and the community structure index(tree crown width,shrubcoverage)were significantly correlated(p<0.05).The above analysis shows that the community characteristics of Pinus tabulaeformis plantation forests in this area are relatively close to natural forests,with rich species composition and high similarity,obvious community structure stratification,and the same dynamic trend of Pinus tabulaeformis populations;high dominance of tree layer and low diversity.At this stage,we should focus on strengthening the protection of native broad-leaved tree species such as poplar and white wax,and adopt appropriate tending measures for plantations with excessive stand density,optimize stand structure to promote the development of understory shrubs and grasses,and increase community species diversity Sexual level and stability.