| The development of urban agriculture is valued when the level of the urbanization and industrialization develops a certain stage.regarded as an important part of urban ecological system, urban agriculture is not only to provide food and raw materials for urban residents, but also plays an important role in the protection of urban ecological environment. The speeding up of Urbanization process urges people to get more material resources from nature to meet the growing needs of life, which directly or indirectly affect the urban ecosystem structure and it s function, severely weakening function of the urban agriculture system service. based on agricultural land use data and other related information, and combined with GIS technology and mathematical statistics methods. This paper choice Xi’an city as the research sample region which stay in a stage of rapid urbanization to study the space-time evolution of urbanization and the change characteristics of urban agriculture ecosystem services from2000to2011in Xi’an city, with social and economic statistical data. We analyze its evolution law to explore the influence mechanism of urbanization to urban agriculture system service function. This study To provide scientific and practical significance for the decision makers of urban ecological, the protection of urban ecological environment construction, and to provide decision methods for the development of Xi’an urban agriculture etc.Through research, this paper draw the following conclusions:First. The growth difference of each district and county of Xi’an urbanization is bigger, the level of comprehensive urbanization have been improved in each district and county. In2000-2011. the level of Xi’an comprehensive urbanization increased by102%. The fastest growing of the comprehensive urbanization level of these districts and counties is Gaoling County, which increased by2.76times, followed by BaQiaoOu and changan district, increased by1.36times and1.2times respectively. Yan Liang county fells slightly, and the rest of the districts and counties changes between36%and90%. Zhouzhi county which increased by0.1353is the lowest in the comprehensive level of urbanization. Three city centers including BeiLin District, Lian lake area. New City District have entered the advanced stage of development of urbanization, with the urbanization level of0.9535.0.7513,0.8616respectively. Wei Yang District. BaQiaoOu. Gao ling county all have entered the middle stage of urbanization development. Yanta district continues to stay in the middle stage; The rest of the districts and counties are stay in the early stage. From2000to2011, the level of the Xi’an urbanization development presents a reduce tendency from the city center to it s surrounding counties m space.second, the urban agriculture total value of ecosystem services showed a trend of the decrease following a first increase from2000to2011. The ecosystem service value of five types of agricultural land from big to small in turn is as followings:forest land> cultivated land> water area> garden land> grassland. Each individual urban agriculture service value between2000and2011has reduced and raised, the overall change is small, and the annual rate of change of each single service function value mainly drop. From the change of the spatial distribution of urban agriculture function value:the farther the distance is far from the center of the city, the higher the value of the urban agriculture ecosystem service function becomes. This shows the main spatial change trend increasing from the center city to the surround.Third. In general, with the improvement of urbanization level, the total ecosystem service value of the Xi’an urban agriculture shows a trend of decrease following the first increase. In space, the main citys districts owing the highest level of the urbanization in Xi’an have the lowest value of the urban agriculture ecosystem services, while the southern suburbs owing the lowest level of urbanization have the highest value of the urban agriculture ecosystem services. The relation of the Urbanization and urban agriculture ecological system service functions presents a significantly correlation, which has a positive or negative correlation. Xi’an urbanization has a huge impact on the ecosystem service function of urban agriculture, by influencing and destructing the ecological environment, ecological system structure and the biological habitat. For example:the urban population growth and the residents living demand heavily influence the environment; industrial wastewater, waste gas, sewage and the living waste all discharge into rivers or lakes, which makes the quality of water became bad, affecting the farmland irrigation and destructing biological habitat of the agricultural system. This also directly affect the plant and animal breeding, resulting in a large number of the biological death in agricultural system. Various aspects of the construction of the city actively increase a lot of living garbage and solid waste. Its processing needs to take up a lot of arable land, grassland, water bodies and other agricultural ecosystem, destroying the structure of urban agriculture system, which severely weakened the function of food production, water conservation and waste management functions of the urban agriculture ecological system. |
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