Quantitative Analysis And Application Of Vegetation Quantity Of Beijing Urban Park Plant Communities

The destruction of the urban ecological environment has become a potential constraint on the development of urban economy and the further improvement of the quality of life of urban residents. How to create greater ecological efficiency in the limited green space has become a key issue to improve the urban ecological environment. The community vegetation quantity size and the ecological benefits of green space has a direct correlation, thus improving the green garden community vegetation quantity has become an important way to improve the quality of green space. The quantitative measurement of the green value of the different green space community has become one of the important topics in the current landscape construction.In order to find out the relationship between the structure of the group and the amount of plants, and to explore the way to improve the vegetation quantity and ecological benefits of the community, in this paper, the influence factors of plant community structure on vegetation quantity were studied by using green amount as a key instrument. Through the investigation of Beijing urban park in 168 plant communities., the community structure was classified according to the tree layer and shrub layer, and the structure of the community was quantitatively analyzed. With the determination of environmental factors, the differences of ecological benefits of communities under different green amounts were analyzed. At the same time, the community samples were evaluated by the method of landscape assessment. The main results of this study include the following aspects:1. The plant community structure of Beijing park green space was classified. The most common structure is the structure with both trees and shrubs, accounting for 58.33% of the total number of the samples. The tree layer is mixed with coniferous trees and broadleaved trees, and the shrub layer is consisted broadleaved trees. In this type of community structure, the overall coniferous to broadleaved ratio is distributed among 1:9-1:3, accounting for 67%, and the number of broadleaved trees is more than that of coniferous trees.2. The results of the study show that there is significant correlation between the plant community structure indicators and vegetation quantity. These indicators include:coniferous tree coverage, broad-leaved tree coverage, tree layer coverage, community coverage, the average height of tree layer, average crown of tree layer, and the average diameter of the tree layer. With these indicators as independent variables, vegetation quantity as the dependent variable,7 single factor regression models are established. And among these variables the average diameter at breast height of coniferous tree layer and the coniferous tree coverage influence vegetation quantity most significantly.By using the regression equation, two multiple regression models which can reflect the vegetation quantity well are obtained. In one model of the independent variables include coniferous tree coverage, broadleaved tree coverage, and broadleaved shrub coverage; The independent variables of the other model are average diameter breast height and tree layer coverage. For the most common community structure, the independent variables of the multiple regression of the vegetation quantity are the coniferous tree coverage, the broad leaved tree coverage, and the broad leaved shrub coverage. In this model, the coefficient of the canopy coverage is bigger, and the influence of it on the vegetation quantity is higher.3. The vegetation quantity of plant community has a certain effect on the temperature, humidity and ultraviolet intensity. The results showed that with the increase of the amount of green, the cooling rate also increased significantly, so there is significant correlation between them. The average cooling rate was 20%. However, there is no significant correlation between vegetation quantity and the increase of humidity or between vegetation quantity and the intensity of ultraviolet radiation.4. The community vegetation quantity and beauty degree were statistically analyzed by using the method of scenic beauty evaluation (SBE). The results showed the plant community can create a good community landscape when the vegetation quantity between 2.2 to 2.4.Based on the conclusions above, this research can provide quantitative control index for the construction of plant communities. It is helpful for estimating the ecological and environmental benefits of urban greening, and for making the limited urban green space to maximize the ecological efficiency and landscape efficiency.