Constructing Urban Ecological Security Pattern Based On Ecosystem Service Value

In the process of urbanization,due to rapid expansion of urban construction land,land use changed a lot,various of ecosystems were impacted and it is difficult to maintain the supply of ecosystem services and functions.Also,the ecological security of urban areas was threatened.This research carried out an in-depth study on the change tendency of ecosystem service value and construction methods as well as strategies of ecological security pattern.This study took Wujiang district of Suzhou which was under rapid urbanization as an example.This research studied characteristics and trend of land use change in Wujiang district from 2004 to 2016,calculated value of various ecosystems along with ecosystem services and functions by adopting ecosystem service equivalent value,analyzed dynamic change degree and potential impacts of ecosystem service value.Considering restoration significance index and actual important index,important degree of various services and functions was determined,Wujiang district ecosystem service equivalent value was optimized.The optimized model is used to guide the construction of ecological security pattern in Wujiang district and explore constructing methods as well as implementing strategies to improve ecological security level of Wujiang district.The results showed that:(1)During the period of 2004 to 2016,land use of Wujiang district experienced a great change.The area of urban construction area increased from 182.33km~2 to391.32km~2 with an increasing rate of 114.62%.(2)Between 2004 and 2016,Wujiang ecosystem service value continuously declined from 20,731 million to 18,833 million.Especially during the period of 2008 to 2012,total ecosystem service value decreased dramatically,of which,the declination value was 1148.6 million and the rate was 5.615%.Among all ecosystem services and functions,the function of food supply enjoyed the declination rate of25.938%,which was the highest.(3)Compared with original evaluation model,the optimized model included the information of dissimilarity of recovery significance and actual importance and so on.In recovery significant indexes,the function of food production,maintaining nutrient cycling and gas regulation had the fastest decrease rate and their indexes were 1.867,1.671 and 1.348 respectively.Among actual important indexes,hydrological regulation,soil conservation,food production and raw material production were comparatively important.(4)Based on the optimized ecosystem service value,the ecological source area under the low,medium and high security level was 120.08km~2,179.7km~2 and184.15km~2 respectively.The ecological corridors with low safety level were mainly distributed in the northeast of wujiang district.The ecological corridors with medium and high safety level tended to develop towards the central and western regions.The ecological nodes were mainly distributed in the east of wujiang district,and scattered in other areas.Reasonable planning of spatial distribution of ecological sources,corridors and nodes can provide a basis for the optimization of ecological red-line and the guidance of reasonable spatial organization of land use,so as to realize the construction of ecological security pattern in Wujiang district and improve the level of ecological security.