Integrated Analysis On The Driving Mechanism Of Land Use And Land Cover Changes In Keriya Oasis Over The Past 40 Years(1975-2015 )

The expansion of city caused by land use and land cover change had become a global problem,and caused a series of social-economic and environmental impacts,such as degradation of water quality,air pollution,loss of biodiversity,social structural problems such as energy consumption and loose.Since 1996,China has experienced a continuous city expansion and even spread to the edge of rural expansion,China's urbanization rate in 2011 exceeded 50%.As a typical arid Region Oasis,the weak economic foundation and fragile ecological environment makes the special impact of urbanization to the Keriya oasis,the contradiction between the limited resources of the oasis and bear population,resource pressure make the study on the relationship between population growth and the oasis land cover change and land use(LUCC)has a special value.Based on this,this paper studied the dynamic spatio-temporal pattern of LUCC and population changes of Keriya oasis from 1975 to 2015.The purpose of this study was to determine the demographic,social,and economic driving forces of LUCC over the past 40 years by using long time series of Landsat data(1976-2015).First,we obtained LUCC images through1976 and 2015 Landsat images.Secondly,the demographic data of 1975 and 2015 were transformed into 500 m * 500 m grid.Then,the LUCC classification image was processed into the area ratio image of each LUCC type in each cell.Finally,combined with the vector data of LUCC type and census data,based on the grid unit method,using global scale Pearson correlation coefficient,least squares method(OLS),geographically weighted regression(GWR)method,we analyzed the relationship between LUCC changes and population changes in 40 years.The spatial heterogeneity of LUCC variation was explained by the variation of population,the ratio of LUCC change and the characteristics of population change were compared in order to analyze the spatial and temporal dynamics of oasis expansion in the past 40 years.The main results were as follows:1.In the past 40 years,the LUCC change of oasis had a causal relationship with population dynamics change in the Keriya Oasis.On the whole scale,there were positive relationship between the population changes and construction land change,and negative relationship between the change of cultivated land and construction land change,between the sparse grassland change and construction land change,between the change in forest grassland and sparse grassland change,between the water change and the sparse grassland change,between sparse grassland of the transition zone and forest grassland change.However,these relationships were not linear change.In the different spatial regions were positively correlated or negative correlation,which showed the spatial heterogeneity and significant diversity.2.The spatial heterogeneity and diversity of correlation showed that the relationship between construction land change and population change in the most areas of oasis are positive,and in some areas of northern had a negative correlation.In the oasis edge,the relationship of cultivated land change with change of forest and grassland were positive,and at the inner of the oasis,there was a negative correlation,land reclamation at the edge of oasis and at the internal played a different role on change of forest and grassland;sparse grassland changes in transition zone of most oasis had a negative correlation,while other small areas showed a positive correlation.Grassland and sparse forest grassland in transition zone of most areas of southern and eastern oasis showed a positive correlation,and negative correlation in most areas in the north and west of the oasis.The correlation between the change of water body and the change of forest and grassland were negative correlation at most of the west and central of oasis.These results explained the possible effects of oasis expansion,such as population migration,uneven distribution of social space,drought intensification,soil salinization and so on.This deep understand to above relationship could provide guidance for sustainable oasis planning and development.3.The driving forces of LUCC that come from population can be divided into direct driving force and indirect driving force.The internal drive force form population changing and the contradiction between growing population and northern arable land with a limited arid environment resulted in the expansion at southern oasis,that can be concluded with the comprehensive effect of the social and economic development in history,and also the result of interaction between self-organization and hetero-organization.The research can provide a reference for the study of other oasis in southern Xinjiang.4.The expansion of Keriya oasis showed obvious characteristics that mainly expanded to the southern oasis and rapid urbanization there;the demand of percapita arable land,urbanization process,the demand of the construction land,the nation's policy increased the extent and speed of LUCC change of Keriya oasis at a certain extent.Population and economic factors had a driving actor in the process of LUCC,also caused incalculable impact on the environment.5.The GWR method showed more heterogeneous characteristics than the OLS method,and showed that the results may have the opposite direction or different size at the local area.In addition to the statistical analysis results of the global scale,the local scale statistical analysis method could reflect the more complex features,and might be closer to the actual situation.In the study,we tried to apply the remote sensing,GIS,and a variety of statistical methods,which would bring us a new understanding of LUCC and dynamic sustainable development of oasis.