Study On Ecosystem Services Of Different Community Models Of Buffer Strips In Urban Fringe

With the economy and society rapid progresses, the pace of urbanization was accelerating, while the corresponding environmental problems, such as urban expansion, ecological land lessening, urban heat island effect, biodiversity loss, atmospheric and water pollution and so on, had threatened our daily life seriously. The buffer strips in urban fringe was significant for controlling urban expansion and improving the state of ecological environment. In this paper, the typical buffer strips in Chaoyang district, Beijing City, were selected. The method of location survey, data collection and fields tests were used to measure and evaluate tridimensional green biomass and its density and the ecosystem services, including biodiversity preservation, CO2 fixation and O2 release, temperature decreasing and humidity increasing, in order to provide academic basis for reasonable decision-making and countermeasures to realize its value, and guide the construction of buffer strips in urban fringe. The main conclusions were as followed:(1) The ecosystem services of buffer strips were related to plant species, crown density and tridimensional green biomass density. The key factor in temperature decreasing and humidity increasing ability was the crown density and tridimensional green biomass density. With the crown density of 60% and above,and the tridimensional green biomass density of 7.5 m3/m2and above, the buffer strips' temperature decreasing and humidity increasing ability will be stronger than the average level. Species was the major force what influenced the tridimensional green biomass and CO2 fixation and O2 release service of buffer strips. Besides species, the crown density affected the tridimensional green biomass and the crown density and tridimensional green biomass density influenced the CO2 fixation and O2 release ability too, but they were less important than species. The key factors of affecting plant species diversity were the cropping system and management and the proportion of water controled the birds' number and distribution. Consequently, growing the plant that had great tridimensional green biomass or strong CO2 fixation and O2 release ability and increasing the species density properly can advance the ecosystem services of buffer strips.(2) Arbor played an important role in the ecosystem services. In the tridimensional green biomass and the ability of CO2 fixation and O2 release, deciduous arbor was better than evergreen arbor and evergreen arbor was better than shrub and herb. Between the shrub and herb, the shrub was stronger in the temperature decreasing and humidity increasing ability, but weaker in the ability of CO2 fixation and O2 release. Therefore, while we chose the species in buffer strips, deciduous arbor was what we must first take into consideration, such as acacia, papermulberry, and eucommia bark. To enhance biodiversity of buffer strips, evergreen tree, shrub and herb were necessary. In many evergreen trees, Chinese pine, white pine can bring huge benefits; in shrub, gold and silver wood, lilac, swida were better choice; Sheep fescue and iris had greater service in herb.(3) The four types buffer strips were distinct in ecosystem services. Arbor-shrub-herb type or arbor-herb type buffer strips had greater effects on the service of CO2 fixation and O2 release, bio-diversity preservation and temperature decreasing and humidity increasing than the others. But not all of the arbor-shrub-herb type or arbor-herb type buffer strips were the best. Its ecosystem services also lied on the species, crown density and tridimensional green biomass density of the buffer strips.(4) The CO2 fixation and O2 release value had the largest proportion in the three kinds of ecosystem services value. However, the temperature decreasing and humidity increasing value and biodiversity preservation value were much smaller. So, if we chose some species what had strong CO2 fixation and O2 release ability, like acacia, papermulberry and Sheep fescue,white pine or some community model like acacia community in Xibahe, white wax community in Xiaojingcun, papermulberry community in Dongfeng Park and iris community in Duzhong Park, the value of ecosystem service will be much larger.