| Plant community not only plays an important role in maintaining the stability and biodiversity of the urban ecosystem and mitigating the urban heat island effect but also is an important carrier to reflecting the urban cultural landscape.In this paper,we selected 20 typical and representative plant communities for field investigation and data collection,analyzed the species composition,diversity,seasonal community canopy structure characteristics and color composition,and selected SBE and AHP methods to evaluate the landscape,and discussed how to construct the urban park plant community scientifically.The results are as follows:1.Among the 20 samples,there are 60 species of garden plants belonging to 35 families and 50 genera.According to the classification of biological characteristics,it can be found that the most abundant specie is arbor,accounting for 40% of the total number of species,mainly deciduous trees.The dominant family is Rosaceae and Oleaceae.Shrub is the second most common specie,accounting for 33.3% of the total species.Evergreen shrubs are the most common species,and Oleaceae is the dominant family.There are fewer herbaceous species,accounting for 26.7% of the total species,and the dominant family is Gramineae.According to the classification of different ornamental parts,it can be found that most of them are red flower plants and yellow leaf plants,while few are fruit plants and branch plants.According to the classification of plant sources,it can be found that most of the plants in Longzi Lake Park are native plants in China,and foreign-introduced plants account for about 1/3 of the total species.According to the floristic classification of families and genera,it can be found that the flora of Longzi Lake Park is widely related to the tropical flora,and the basic properties are mainly north temperate and have obvious transitional properties.2.According to the quantitative characteristics of the plant communities,the dominant species in most communities are arbors,and the evenness of the communities increase with the decrease of the dominance difference between the arbor and shrub layers.The more complex the community structure is the more species and the greater the specie diversity.The specie diversity of arbor and shrub communities is generally greater than that of other plant communities.3.Analysis of canopy characteristics of 20 plant communities shows that leaf area index(LAI)in summer is the highest among the three seasons in spring,summer and autumn,and there is little difference in LAI between spring and autumn,consistent with plant growth law.By analyzing and comparing different types of plant communities,we find that canopy structure is heterogeneous among different sample plots.Leaf area index(LAI)is significantly correlated with the dominance of the arbor layer,and understory light decrease with the increase of leaf area index and community canopy density.4.The color of plant community landscape quantitative results show that:(1)The overall color of the spring plant landscape covers nine kinds of hue;summer and autumn have thirteen kinds,most of them are yellow-green(H5)and green(H6),different hue types have different change trends in three seasons,H1,H3,H4,H5,and H6 ratio has significant differences in three seasons.(2)In the three seasons of spring,summer and autumn,the green color is dominant;different season has a different green degree,warm green accounts for the most in spring,cold green begin to appear in summer,and the proportion of cold green reaches the highest in autumn.Yellow and red colors are auxiliary;red color mainly appears in the spring,and the yellow color ratio reaches the maximum value in autumn.There is a very small amount of blue-purple color as an ornament.(3)There is little difference in saturation and brightness among the three seasons,with moderate saturation and brightness predominating in spring and summer,and low saturation and lightness predominating in autumn.5.The results of the SBE method show that there are 3 sample plots belonging to grade I landscape,5 sample plots belonging to grade II landscape,4 sample plots belonging to grade III landscape,6 sample plots belonging to grade Ⅳ landscape,and2 sample plots belonging to grade V landscape.The public prefers a plant community with complex structures,a sense of hierarchy,low color values,a moderate proportion of green,and colorful but not too complex plant landscapes.Different people have the same aesthetic attitude towards different landscapes and simultaneously show some differences in the same landscape.Among the different season landscape,the spring landscape is more popular with the public.The results of the AHP method show that among the 18 factors,community permeability,leaf area index and color quantity occupy the largest weight;according to the comprehensive evaluation index of plant landscape,in 20 sample plots,grade I landscape accounts for 5%,grade Ⅱ landscape accounts for 65%,grade Ⅲ landscape accounts for 25% and grade Ⅳ landscape accounts for 5%.The overall plant landscape quality of Longzi Lake Park in Zhengzhou is good.The evaluation results of the AHP method and SBE method are generally consistent.Through the correlation analysis and multiple linear regression analysis,we can find that the visual impact of color,species diversity,and color quantity of plant communities are the main factors affecting general aesthetics.The plant community species are rich in Longzi Lake Park and have a high uniformity index.The leaf area index and community canopy density of the plant communities significantly affect the forest light environment.The seasonal change of plant landscape color is general.Among the three seasons,the spring landscape is most popular with the public,and the Arbor-Shrub-Grass community is more popular among the different community types.The landscape quality can be predicted by the evaluation model constructed by the color visual impact,species diversity and color quantity.The research results can provide a reference for constructing plant community landscapes with good ecological benefits and high ornamental value and provide theoretical support for selecting plant species and landscape shaping in urban park. |
