Study On Ecological Construction And Sustainable Development Of The Green System Of Changchun City

With the rapid economic growth, sharp increase in urban population and denser buildings in the urban area of our country, people have had a deep understanding of serious damage to the entire urban ecological environment causing by rapid urbanization, which has become a potential confinement factor in further development of the city and further improvement of people's quality of life. That "humans long for nature and cities call for green" profoundly reveals the basic rules that should be followed in the modern urban environmental construction and reflects people's common wish in modern society. Setting up an ecological system with the urban green plots as the core that has a leading effect on the urban land use and spatial arrangement is a urgent need to implement the urban sustainable development strategy under the present background condition of urbanization.Changchun City, the capital of Jilin Province, is rapidly moving towards building a modern metropolis. With the adjustment of the urban structure and increasingly expanding urban size, it will certainly make still greater demands on urban greening as an important means to improve the urban environment. It is the major objective of urban greening construction to seek the ecological benefits of urban green vegetation and bring its role in environmental improvement into full play while at the same time beautifying the urban environment. In the limited urban land and space, the way to improve the ecological benefits of urban greening is to pay attention both to the increase in the quantity of urban green area and to the improvement of its quality and level. In the specific urban condition, building artificial plant communities with harmonious relations between ecology and landscape to make urban land resources utilization achieve the optimum combination of the ecological, social and economic benefits is the key to improving the quality of urban green.This paper systematically analyzes in detail the distributional characteristics and plant composition of various urban greens and green structure in the central urban area of Changchun City using the RS and GIS techniques, dissects the existing problems in Changchun's urban green system in such six respects as the ideal of urban green system construction, green system layout planning, urban green design, garden tree species, plant configuration, and maintenance and management, and points out the method of calculating the grade of ecology frailty of plant community, analyses all kinds of greenery plots in Changchun in the aspect of the grade of ecology frailty, discusses the relationship between the grade of ecology frailty and landscape effect, as well as the relationship between it and greenery plot structure, it and greenery plot maintenance, it and interference of mankind ,expounds that constructing compound biocoenosis scientifically is the only way out to reduce the grade of ecology frailty of greenery plot.In order to thoroughly solve the problems existing in the green system of Changchun City, improve the ecological benefits of the urban green system and achieve sustainable development in the urban green system, firstly, the author describes in detail the theory about scientific layout of the urban green system, analyzes the reasonable quantity of urban green and put forward his own opinion and method about the scientific layout of the urban green system in the urban territory and the city proper of Changchun. Lack of urban tree species selection and planning is an important factor restricting sustainable development of the urban green system in many cities of the country including Changchun. The author, on the basis of a careful investigation into the existing trees species used in the city, conducted a graded evaluation of173 common garden plants in the city by adopting the comprehensive evaluation and graded selection method for the urban greening plants and conducted a selection of and planning for the garden plants in Changchun. Under the condition of relatively limited urban green, seeking to establish a reasonable multiple larger planting structure method is an important measure to improve the ecological benefits of urban greening and is also the starting point of research in this paper. The author describes in detail the principle of scientific configuration of plants used for the urban green system first and then investigates the structure and plant composition of the typical original zonal plant communities in the territory of Changchun City and the typical plant communities in the city proper and establishes some reference models for multiple layer structure of plant configuration in Changchun City by using the principle of landscape ecology and method. In the research on the scientific maintenance of the urban green system, the author mainly focuses on the maintenance and management of the street and road greenbelt., and points out the soil dererioration of physics, chemistry and biology's quality is the modern city construction has brought a universal evil to streets and roads of cities and puts forward some effective measures for improving the city's soil such as raising the content of organic matter in soil improving the ventilating condition under tree and ameliorating physical chemical properties of soil.Practice has shown that an application of the RS and GIS techniques and methods to the detailed analysis of the present situation of the urban green is characterized by time and labor saving, and being capable of accurately finding out the problem that exists in urban greening. To study plant configuration, mimic nature and design of the compound plant community in different urban green conditions by using a combination of landscape ecology, natural geography and garden architecture is the only way to achieve sustainable development in urban greening, which is innovative to a certain extent. So far, there has been no relatively successful urban tree species planning in the cold city. Selection of urban garden plants is basically based on experience, resulting in great waste of investment in urban greening. In recent years, some work has been done on the selection of tree species in big cities, but they are mostly spontaneous, scattered and closed studies conducted individually or within a small range, lacking main research direction needed in practice and basis of large quantities of survey data, which are basically at the early stage. The author has made the detailed, scientific and high-operability Changchun garden tree species selection planning by using the knowledge In dendrology, geobotany, plant taxonomy, plant ecology, meteorology and other branches of science, filling in the gap in the study on the selection of tree species in the cold city to a certain extent; put forward for the first time the concept of ecological fragility of urban green plant community and its quantitative indicators and various measures to improve the urban street soil, further achieving scientific maintenance of the urban street green, which is innovative to a certain extent.A comprehensive study on the construction of the urban green system and sustainable development by using the RS and GIS techniques and the theories and methods of landscape ecology, geography and other cross-disciplinary sciences, starting with an analysis of the present situation of the urban green system, in the respects of scientific arrangement of the urban green system, garden plant selection and planning, scientific plant configuration of the urban green system and others can avoid taking a roundabout course in theconstruction of the urban green system and reduce the waste of investment in it, having an important theoretical and actual significance.