Effect of temporal and spatial changes of population on land use and cover change in Keriya Oasis in past 40 years

Abstract: The study on the regional land use and land cover change (LULC) and the drives of human activities toward LULC change is significant to global land science. In a typical arid regional oasis, the contradiction between the limited resources and growing population pressures makes the researches on the relationship between population changes and LULC changes having a special and significant value. This paper studied the dynamic spatio-temporal pattern of LULC changes and population changes of Keriya oasis and the interaction between each other from the year of 1975 to 2015. First, we obtained LULC images of 1976 and 2015 Landsat images. Secondly, the demographic data of 1975 and 2015 were transformed into 500 m× 500 m grid. Then, the LULC classification image was processed into the change ratio image of each LULC type in each cell. Finally, combined with the vector data of LULC type and census data, based on the grid unit method, using global scale pearson correlation coefficient, geographically weighted regression (GWR) method, we analyzed the relationship between population changes and LULC changes in the past 40 years (1975-2015). The spatial heterogeneity of LULC variation could be explained by the variation of population, and the ratio of LULC 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 results were as follows: 1) In the past 40 years, the manifestation of oasis development included that the large increase of population and centralization to town center, and the buildup land and arable land expanded forward to south, and forestland increased with obvious fragmentation, and the significant reducing of grassland and water area. 2) In the past 40 years, the LULC change of oasis had a close relationship with population dynamics change in the Keriya Oasis. The direct driving mode of population development was buildup land growth and arable land growth, and the indirect driving mode was the fragmentation of forestland and grassland decrease and the significant reduce of water area. On the whole scale, there were positive relationship between the population changes and buildup land change, and negative relationship between the change of arable land and buildup land change, between the sparse grassland change and buildup 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, they were positively correlated or negatively correlated, which showed the spatial heterogeneity and significant diversity. The internal driving force from population change and the contradiction between growing population and northern arable land with a limited arid environment resulted in the expansion at southern oasis. It 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 case study for the research of the other oasis in southern Xinjiang. 3) 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 upon the possible LULC changes with the population and society development, and could provide guidance for sustainable oasis planning and development.