Abstract:

Urbanization affects the structure and function of ecosystem in a city. The “urban-to-rural” gradient is an effective technique to examine spatial pattern and processes of urbanization. Quantitative studies on interaction between landscape pattern and function of urban ecosystem have become the core issues of landscape ecosystem in city. In addition, terrestrial ecosystem carbon cycle research has been the hot issue of global ecosystem, while the urban ecosystem as a type of terrestrial ecosystem is an important source of carbon. It is therefore important for us to study ecosystem carbon cycle in urban area. Although urban green space is an important part in city, we know little of its function in carbon storage. This paper, based on remote sensing images, used geographic information system (ArcGIS 93), landscape pattern analysis (Fragstates 33) and statistics (SPSS 17) to calculate 6 commonly used indicators including physical variables and landscape metrics. Principal components analysis and multiple linear regression were used to assess the urbanization level of Shanghai in a direction. Using biomass regression equations and UTC area to estimate the carbon stocks of urban green space in an urban-to-rural gradient. The results showed as follows. (1)Urbanization indictors can be used to describe the level of urbanization. The gradient of “urban-to-rural” showed spatial differentiation. This kind of differentiation is consistent with the history of development in Shanghai and function of each region. (2)The total carbon storage and average carbon density of urban green space were 4,475, 4107 Mg C and 711 Mg C /hm2 in study area. (3)Distribution of carbon storage along the transect were as follows: the high carbon storage green space is more dispersed in Pudong and Center districts, which were dominated by small green space in residential areas, the high carbon storage green space is more concentrated in Fengxian and Minhang districts, which were dominated by largescale nursery; carbon density trends in different regions are urbanpublic park>residential green space >attached green space>street trees