| City is the political and economic center in one region, and also the area where the human had the most disturbance on landuse. Although the urbanization process began late in China, the speed was very large in the past three decades years. With the urbanization, many urban problems, including the loss in bio-diversity, the resources exhaustion and environment degradation, are more and more serious, and have bad effects on the human lives. But as one vital part of the urban infrastructure constructions, urban forest owns several functions on city society, economy and ecology. The parks, which has the most stability and the unalternative funcitons such as maintaining the bio-diversity, purifying the environment in the city greenland, has gained more and more attentions. And the fast-developing RS-tech and GIS-tech are being widely applied to the urban greenland researches. Therefore, the objests of this paper are as follow: first, to build a new urban vegetation classification system which can better connect with RS-tech and GIS-tech; second, to analyse the distribution pattern of urban vegetation patches; three, through CITYgreen model, to calculate the ecological services of all the parks within the 5th Ring Road as a whole, so as to improve the systematicness and accuracy of this calculation and help the parameters customized during this model application in our country. So in this paper, the QUICKBIRD image within 5th Ring Road in beijing in 2005 was selected, combined with the data from the field survey and literature. Then the patch analysis module and the spatial analysis module in GIS software, CITYgreen 5.0 model in ArcVIEW software and SPSS 16.0 software were used. This paper consisted of three parts: the urban vegetation classification and the vegetation pattern analysis, the ecological services valuation and the accessibility of the parks. The results showed that the urban vegetation within the 5th Ring Road could be classified as 6 1st Group, and 15 2nd Group. Since the roof greening was an effective way to enhance the tridimensional green biomass in city built area, it was listed in 2nd Group as well. And for every kind of land use, the paper has built the interpretation keys. In the city center, there was the lowest landscape diversity and evenness, which were only 1.70 and 0.64 respectively, but in contrast, the landscape diversity and evenness got to the peak in the outskirt of built area, and the number reached to 2.05 and 0.76. The arbor, arbor mixed with by shrub and herb, herb and scattered trees were the main vegetation types within 5th Ring Road in Beijing. The vegetation patches within 5th Ring Road were mainly on the big, middle and small scales, and rarely were on the extrmely big and huge scales, the area ratio for the former was over 90%, but for the latter, only less 10%. The arbor patches and the scattered trees patches were usually small and aggregated in the center area, but the other two aggregated in the outskirt. There were more vegetation patches scattered in the north than in the south, but at the meantime, the human disturbance here was very serious, which can be related to the city development situation. The ecological services value of all the parks within 5th Ring Road could reach to 442.78 million dollars, and there was the lowest value in the area between 3rd and 4th Ring Road, which was only 12.7% of the total value in the built area, and there was the higest value in the area between 4th and 5th Ring Road, which could be 3.5 times as much as the area between 3rd and 4th Ring Road, the value in the area within 2nd Ring Road and between 2nd and 3rd Ring Road is median; in the north part of the built area, the value was higher than in the south part, and the value in the northwest and notrheast part of every ring belt were over 50% of the total value of the ring belt. The park accessibility was very high, in 93% of the total built area, one could reach the nearest park within 30 minutes, but in the outskirt area of the built area, the accessibility was slightly low. Hence, in the future, the vegetation constructions in Beijing built area should accord with the regional situation. In the center area, the vegetation construction should pay more attetion to the greenland management, and also need to increase the street greenbelt area; in the area between 2nd and 4th Ring Road, little parks are needed, and at the same time, all the parks should have its own style; in the outskirt area, protecting the original greenland and strength the isolated greenland constructions are the two primary work. |
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