Xi'an Urbanization Affect The Mechanism Of Ecosystem Services Research

Ecosystem not only provides products for human but also provides living environment, which makes a variety of ecosystem services, human society can survive and develop depending on ecosystem services. With the development of urbanization and industrialization, ecosystem was affected more extensive and profound by human activities,environment, ecosystem structure and its evolution have been changed, resulting in ecosystem services have been seriously weakened.The paper assessed and graded the level of urbanization and ecosystem services value of Xi'an in 1988,2000 and 2009,which based on remote sensing image data, socio-economic statistical data and other relevant information, combined with the RS, GIS technology.Then through studying the level of urbanization and ecosystem services of Xi'an in the space-time evolution, the paper studied the universal mechanism of urbanization affacting on ecosystem services,finally take Xi'an as a example,revealed the internal mechanism of urbanization affacting on ecosystem services.the study can provide ecological theory for decision-makers and promote Xi'an better and faster development.Through studying, results are as follows:First, Urbanization of the counties showed significant imbalance。The comprehensive urbanization levels of the counties of Xi'an are all improved. The comprehensive urbanization levels of the city are improved by 108%. The main city districts are improved by more than 99%,the level of rural counties have a large different, range from 27% to 117%. The comprehensive urbanization level of counties are divided into two stages.The urbanization level of three central districts is in the intermediate stage of urbanization, and the remaining counties are in the initial stage in 1988. The counties have a different degree of increased from 1998 to 2000, but the stage which they did not change. In 2009, the urbanization level of beilin district, xincheng district and lianhu district were 0.877,0.818 and 0.729 respectively,they were involved in the advanced stage of urbanization, Weiyang District, Baqiao District, Yanta District entered the intermediate stage of urbanization.The development pace of Lantian is slowest in four counties, the urbanization level is 0.088.Second, the ecosystem services total value was 9.4,10.8 and 9.7 billion yuan in 1988,2000 and 2009 respectively, as increasing at first and then decreased. The ecosystem services value of six land use types were ordered by descending,forest ranked first,farmland ranked second,the ecosystem service of construction land is lowest.The order has changed from 1988 to 2009.Soil formation and conservation, biodiversity generation and maintenance, gas adjusting function remains the top three,the other ups and downs a little.Seen from the change rate of the ecosystem services value, most of the functions are increasing, only the value of water conservation, the waste disposal and food production capabilities reduced 30.3%,21.8% and 16.4% respectively from 1988 to 2000.The ecosystem services value of counties in qinling mountains remain the highest,are higher than 1 billion yuan in zhouzhi county,hu county,lantian county and chang'an district,The ecosystem services value was from 0.1 to 1 billion in northern of Xi'an,The main city district were lowest, total value was negative. Only the total value was negative in central city district in 1988, become negative in weiyang, yanta and yanliang district after 2000.Third, with the urbanization level increasing, ecosystem service value of Xi'an increased at first, then show a decreasing trend.In space, the urbanization level of main city districts are highest while its ecosystem service value are minimum in Xi'an, the urbanization level of southern suburbs are lowest while its ecosystem service value are highest in Xi'an.After analyzing the correlation among them,get the finding:urbanization was significantly negatively correlated with water conservation, the waste disposal and food production fuction,while was weakly correlated with the other fuction.Keeping and provising ecosystem services depened on three inseparable elements: environment, ecosystem structure and biogeochemical cycles. Urbanization mainly influences water conservation, waste processing and food production function of ecological system through these three elements in Xi'an.Urban population is growing,which has brought tremendous pressure on water environment. Polluted water of life was sewaged into rivers and lakes, the quality of water would deteriorate, and then all kinds of water habitats were polluted, resulting in a large number of aquatic organisms die, breeding animals and plants directly affected, weakening and food production and waste processing function of ecosystem.Garbage and solid waste disposal needs to occupy farmland, grassland and other ecosystems, seriously damaging food production function of ecosystem. Construction land and urban infrastructure takes a lot of land and water, destructed the structure of ecosystem and weakened severely food production, waste processing and water conservation function of ecosystems.