Studies On Plant Diversity Analysis And Optimization Countermeasures Of Road Green Space In Tianjin

Based on some principles and methods of relevant disciplines, such as landscapearchitecture, synecology, botany etc., the dissertation, the street trees application, plantcommunity diversity, plant ornamental characteristic and community spatial structure wereanalyzed, the application status and developmental countermeasures of street trees wereexplained, the evaluation standard for community spatial structure of road green space wasestablished community modes suitable to different locations, different environment, differentfunctional requirements of road green space were optimized. The main results were as follows:1. Street trees application in TianjinBased on an investigation of the street trees of137main streets in the urban area of Tianjincity, the present situation and existing problems were analyzed. Some suggestions and strategieswere proposed for improving the current application situation and enriching the street trees ofTianjin city. The results were as follows:(1) There were16species of street trees belonging to11genera in10families inurban road green space in Tianjin. The species of street trees wasrelatively single, but most of them were regional trees, thus reflecting the flora characteristic.(2)The street trees were generally healthy. Most application of street trees in the collected data wereless than4m in crown, range from11to20cm in diameter, and from4to9m. The crowns of quitea few senior trees were heavily cut.(3) The results of commonly used coefficient of street treesshowed that, Fraxinus velutina, Sophora japonica and Platanus orientalis were the most widelyused, far more than the remaining13species. A large number of single street trees formed speciallandscape of Tianjin, also led to the homogenization of the landscape.(4) According to theapplication problems of street trees, It was thought that laying stress on application plan,strengthening the scientific disposition, perfecting the managemental system, paying closeattention to the fine variety breeding and popularization, and constructing street trees landscapewith rich local characteristics were the key of the urban road greening in Tianjin city.(5)Formulating Monthly Calendar on Maintenance and Management of Street Trees in Tianjin Cityprovided a scientific reference for the reasonable development and scientific application of theTianjin street trees.2. Plant community diversity in road green space in TianjinFrom the perspective of community ecology, the diversity index, evenness index, richnessindex and community similarity index of21roadside green space,16street corner greenbelt,10overpass green space and6waterfront green space were analyzed, the diversity of arbor layer,shrub layer and plant community was explaimed. The results were as follows:(1) The speciesnumber of the trees in arbor layer were generally from2to5. The plant species were unitary, causing simple composition structure. The average D indexes concentrated in0.5, and were littledifference in each type of sample plots, H′indexes were from0.79to0.98, and were greatdifference in each type of sample plots, D and H′had the same trend. The average evennessindexes in different types of road green space were similar, ranging from0.71to0.80.(2) Thespecies number of shrub layer were more than that of arbor layer, the waterfront green space wasoverall lower than roadside green space, street corner greenbelt and overpass green space. Theaverage H′indexes range from0.82to1.50, were about two times than D indexes. The diversityindexes of street corner greenbelt and overpass green space were higher than other types of roadgreen space. The average evenness indexes were great difference, ranging from0.51to0.78.(3)The species number of the sample plots was about10, only a small number of samples had acertain gap. The average D indexes concentrated around0.5, H′indexes from0.85to1.24, H′index was more sensitive than D index along with the changes of species richness. Jsiand Jswindexes changed greatly, but had good correlation for the same sample. The samplinginvestigation showed that the community diversity of Tianjin road green space was few and theevenness was slightly higher than some cities.(4) The community similarity index was low in allkinds of sample plots, basically at the level of dissimilar and moderate dissimilar.(5)Sortingcomprehensive indexes of plant diversity of road green space(such as roadside green space, streetcorner greenbelt, overpass green space and waterfront green space)could provid a scientificreference of species selection and configuration.3. Ornamental characteristics of landscape plants in Tianjin road green spaceAccording to the investigation results, the species composition structure, applicationcharacteristics and ornamental characteristics comprehensively from flower, fruit foliage andshape were analyzed. The results were as follows:(1) There were37species of ornamentalflower plants, accounting for50.68%of the total investigated species. The plants in Rosaceae,Leguminosae, Caprifoliaceae and Oleacea had a large proportion. The anthesis was mainly inspring and summer, including white, yellow, red and blue colors. The species of white flowerplants were the most abundant, accounting for35.14%of the total. Ornamental flower plantswere overall less in road green space, and the application frequency was lower.(2) There were25species of ornamental fruit plants, accounting for34.25%of the total investigated species. Therewere7ornamental fruit species that the application frequency was more than10%, far less thanthat below10%. The fruiting period was mainly in June to October, and there were persistentfruits from November to the next April. fruit color mainly includes green, red and yellow. Therewere11kinds of fruit types, and the dominant fruit types were drupe and pome.(3) There were49species of ornamental foliage plants, accounting for67.12%of the total species. The Autumnchromatic leaf plants and evergreen plants were relative more employed. Some plants(such asSalix babylonica, Ribes mandshuricum, Platanus orientalis, Cornus alba ect.) had multipleornamental characteristics with higher potential application in landscape.(4)There were49species of ornamental shape plants, accounting for67.12%of the total investigated species. The number of evergreen plants was more than other types of plants. In three types of ornamentalcharacteristics, the order of the species number was figure plant﹥modelling plant﹥crownprofile plant.(5) Compiling the Application Guidelines for Ornamental Plants in Road GreenSpace of Tianjin City provided a scientific reference of species selection and landscapeoptimization in road green space.4. Spatial structure characteristics of plant communities of road green spacein TianjinBased on the investigation, the spatial structure characteristics of53plant communities ofroad green space were evaluated, and optimization modes suitable for plant communities wereput forward. The results were as follows:(1) Horizontal structure was flaky combination andpoor promiscuity. Community density was located in a reasonable interval on the whole, butthere was some difference between the sampling plots. Aggregation index R indicated that plantswere mainly uniform distribution, while assemble distribution was subsidiary.(2) Verticalstructure was payed attention to the configuration of arbor and shrub, which caused thechangeable spatial level. The probability of adjacent plants belonging to the same layer wasgreater than belonging to the different layer. The rate of stand level was not rational.(3) Theaverage community diversity indexes were from0.66to0.93in roadside green space, streetcorner green belt, overpass green space and waterfront green space, the average communityevenness indexes were from0.62to0.77, the average community richness indexes were from7.83to12.31.The species composition structure of plant communities in street corner green beltwas more abundant, and plant configuration was more reasonable.(4) Although seasonalstructure considered the four seasons to have the scenery as far as possible,the number ofevergreen species was still limited.(5) Through introducing AHP method, the spatial structurecharacteristics of plant communities was evaluated, optimize modes suitable for each type ofTianjin road green space were put forward.According to the results of above-mentioned investigations, the following optimizationways of plant application in Tianjin road green space were put forward: Innovationing roadlandscape concept, enhancing the level of plant configuration, increasing plant developmentefforts, regulating planting techniques.