干旱区生态环境知识资源中心

With the modification of urban structures and increasingly expanding urban areas, there will be a greater demand for urban greening as an important means to improve the urban environment. Urban green space systems are the main natural productive areas that play an important and positive role in ecological structure of the city. Changchun city in northeast China as was selected case study region for green spaces. Remote sensing data from SPOT 5 and the American Landsat TM data were used to extract vector data of urban borders and green spaces by man-computer interactive interpretation method based on experience. Also, the Normalized Difference Vegetation Index (NDVI) was estimated by a quantitative remote sensing method. The vegetation fraction is a general and quantitative index related to vegetation growth and has many important applications in evaluating land desertification, water resources, regional ecology, and global change research. The fractional coverage of vegetation was selected and estimated by "vegetation-impervious surfaces -soil" and physically explicit linear spectral mixing models. The spatial distribution of different green space types, compositions, and vegetation coverage were further analyzed by spatial analysis technology in a geographical information system. The results show that attached green space covered the highest area in Changchun city, followed by parkland with the two types accounting for 76.5% of the total area. Residential green space covered in the fourth largest area at 5.0%, which indicated that there was some green space associated city residents’ daily life. The areas containing deciduous trees is largest compositional fraction at 45.1% of all the green space followed be grassland, with the two types accounted for 89.7% of the total area. Farmland and evergreen tree comprised the remaining small proportion. There are clear differences among vegetation coverage in the green space of Changchun city in terms of the NDVI (Normalized Differential Vegetation Index). Due to the distribution of the large amount of water in park land of Changchun city, the NDVI and vegetation fraction value was much lower in the whole park land. From the composition of green space, the results showed that the order of vegetation coverage was evergreen tree > deciduous trees > farmland > grassland.