Value Assessment On Forest Ecosystem Services Features In The Downtown Area Of Chongqing

As the elementary producer of the urban ecological system, urban forest plays important roles to the urban ecological system. Maintaining and improving ecological service function is the basis of sustainable development of city. Chongqing is the western major ecological function district and the eventful part of the Three Gorges reservoir area. The components, structures, functions and services of the urban forest ecosystem in Chongqing play significant parts to maintain stable operation of the Three Gorges Reservoir, protect the ecological security and build a solid southwest of ecological corridors.This essay, taking the downtown area of Chongqing for the study, under the guide of the science of urban forest, forest ecology, ecological economics and urban ecology etc., overviewed the present researching status and the development trend of ecological service function at home and abroad, discussed the concept, range, characteristics and types of urban forest.With the MODIS-NDVI data as the forest vegetation cover change information sources, analyzed the space characteristics and distributions of the downtown area of the Chongqing and with the vegetation coverage of 0.75≤NDVI≤1.0 to determine the forest ecosystem area in the downtown area of Chongqing, and made use of the expenditure method, travel cost method, shadow project method and the carbon tax to value the urban forest ecosystem service value. The results are as follows:1.Between 2000-2008, the NDVI average value showed the fluctuating trend. In 2000, the average maximum NDVI is 0.5656, followed in 2008, which is 0.5652. In 2006, the average minimum NDVI is 0.5023, the sequence of the NDVI average is 2000>2008>2004>2002>2006.2.Between 2000-2008, the average NDVI of the downtown area of Chongqing was 0.6949. Banan District,s average NDVI is the largest, Beibei District followed by an average NDVI of 0.6858, Yuzhong District had the minimum average NDVI, which is 0.3616, the district order of the NDVI average is Banan District>Beibei District>Yubei District>Shapingba District>Jiulongpo District>Nanan District>Jiangbei District> Dadukou District>Yuzhong District.3.In the aspects of the topography, the forest coverage is consistent with the mountains distribution of the downtown area city of Chongqing. The ridge had the high forest vegetation coverage, and the NDVI is large. The tank and the low dam in the mountain valley and other low-lying place had the low forest vegetation coverage, the NDVI is small.4.With the vegetation coverage of 0.75≤NDVI≤1.0 to determine the forest ecosystem area in the downtown area of Chongqing. It showed that urban forest ecosystem services had ecological functions, the product functions and social functions. Ecological functions included water conservation,soil and water conservation,absorbing CO₂ and releasing O₂,refreshing air,regulating micro-climate,landscape tourism and biodiversity. Social functions included providing science education,culture and education,and employment functions.5.Studying on forest ecosystem services features in the downtown area of Chongqing, the results show that: in 2008, the total value of the forest ecosystem service features is 20825.39×10⁶ yuan/a, and it accounts a small part of the GDP of the Chongqing in 2008. The values of each ecological service functions are following(unit:yuan):water conservation 12914.31×10⁶yuan/a, soil and water conservation 1372.38×10⁶yuan/a, absorbing CO₂ and releasing O₂ 1373.02×10⁶yuan/a, refreshing air 551.07×10⁶yuan/a, regulating micro-climate537.66×10⁶yuan/a, landscape tourism516.00×10⁶yuan/a, biodiversity533.46×10⁶yuan/a, production products1375.26×10⁶yuan/a, science education 1.25×10⁶yuan/a, social employment 829.04×10⁶yuan/a, cultural values 650.10×10⁶yuan/a.Combining the present construction status and the destination demand of the urban forest of the downtown area of the Chongqing, according to the basic principles of urban forest management, this essay puts forward the measures to improve the ecological service function of urban forest. The measures are establishing scientific programming system, perfecting technical supporting system and managerial system, developing the culture of urban forest.