Studies On Urban Forest Pattern Optimization In Beijing

The study range is the four corners of Beijing, and utilize 1985, 1995, 2000 and 2007 Landsat-TM remote sensing image(1:100000 scale) and 1992, 2001 land use present map (1:10000 scale) as data source. With combined 3S and measurements on the spot, adopted different scale data and classified standard, in the method of qualifying and quantifying, landscape and urban forest pattern status in quo, change of Beijing are systematically analyzed, especially urban forest of Beijing distribution, structure and existent question. Base on foregoing study and combined main environmental issues in Beijing, the relativity between urban forest and environmental issues is researched, and quantifying target is put forward. At last, the study put forward urban forest pattern optimization project, and serve for capital urban forest construct. The main results as follows:1. Beijing is provided with typical urban landscape, forest land is the maximal and basal landscape patch type (area proportion 42.534%), glebe field (28.754%),spinney land and urban (26.912%) and town residential landuse (10.344%) are main landscape patch categories in Beijing. From landscape, landscape patch types and landscape patch categories levels, landscape patch distributing centralize, and patch shape is simple, main landscape patch fractal dimension indexes are under 1.1, so urban landscape pattern is high influenced by human disturbance.2. From 1985 to 2007, Beijing landscape pattern variational characteristics are as follows:(1) During 1985-2007, patch types and categories change is little, but area and patch number of patch types and categories change distinctly. Town residential landuse area increased 7.66% of Beijing total area, farmland and forest land area decrease in the mass. The total patch number increased at first then decreased. taking one with another, the total number is decreasing, and patch number of farmland and forest land are most distinct.(2) Natural and half natural patch is high influenced by human disturbance. Human disturbance make landscape patch types distributing more centralized and patch shape simpler, greater effect in influencing main patch types and categories ,so Beijing landscape pattern indexes changed obvious. (3) From the research to landscape pattern change of representative districts in Beijing , far plain suburb landscape change is most obvious form 1992-2001, and other regions change relative less. But with city durative enlarge of Beijing, the landscape far half mountainous suburb maybe have biggish changed in recent years.3. Beijing urban forest existing and variational characteristics from 1985 to 2007 are as follows:(1) urban forest resource is deficient and uneven distributing. Forest area in mountainous region is about 75% of Beijing total forest area, and in city and plain region where population centralized is obvious lacking. Undesirable structure and tree species simpleness etc are main problem in existing urban forest, influence urban forest effective exert its zoological function(2) urban forest landscape indexes show: urban forest fragment increased form 1985 to 1995, and decreased form 1995 to 2007, but as a whole, Beijing urban forest fragment is degressive, especially woodland and spinney land. Human disturbance make urban forest patch simple ,and woodland is influenced is most, Different urban forest categories are mutual transform, so the change of Beijing urban forest is very obvious.(3) From the research to urban forest change of representative districts in Beijing , form 1992-2001 urban forest construct obtain effect, and in outskirts and far plain suburb change more obvious than other region. Human disturbance reflect occur in each region, but its function is different.4.Beijing environmental problems hold severe, and atmospheric and water pollute, soil and water loss, hot island and yawp are leading problems,and take on territorial characteristic. Based on research on relativity between urban forest and these environmental problems, urban forest can effective improve environmental quality in Beijing. And for the aim of improve environmental quality, Beijing forest overlay should attain 35% at least in citywide range, and local-areas being severe environmental problem should be provided with higher forest overlay.5. Through the study on urban forest needed capacity, Beijing's forest coverage is up to par in citywide range, but montanic forest coverage, plain covered with trees and average forest area are lacking, and CO2 and O2 balance is incapable;form the point of heat and balance CO2 and O2 balance,urban forest the city zone and suburb is lack. There is urban forest developmental potential space,but the city zone and suburb area need be compensated form urban forest in circumjacent region.6. On the based of the above results and ecological network system, the author drived whole region into city area, plain and mountain area are needed at the point of planning thoughts of running-through forests and water . Based on characteric of urban forest in there regions, Beijing urban forest pattern optimizatize, the resule show all Beijing forest coverage is 40%, mountain area is 52%, plain area is 22% , and tree coverage is respective 55%, 73% and 28%, special areas needs to urban forest are satisfied in urban forest pattern optimizative plan.During the study of Beijing urban forest pattern optimization ,the advices about urban forest development could be induced: In the condition that urban forest area can't satisfy for the need of urban forest construct in highly urbanized region, we should gain benefit from three-dimensional space, and strengthen forest management, develop upright virescence are effective measure. Urban forest must establishes good ecological relationship with its surrounding environment, by connecting the inner city with outside space, cities and regions, increasing the continuity relief the green space shortage within the building area and environmental quality on regions scale. Urban forest with integrated functions will come into being throughout the whole country, and insures urban environment sustainable development.