近40年克里雅绿洲人口时空变化对土地利用/覆盖变化的影响

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

    • 摘要: 研究绿洲区域土地利用与覆盖变化及人类活动对土地利用与覆盖变化的驱动作用,对全球变化科学具有重要意义。该文通过精确空间化的1975年和2015年人口数据与土地利用与覆盖(land use and land cover,LULC)数据,运用网格单元法、线性相关、空间自相关、空间回归模型等方法,兼从全局与局部定量分析克里雅绿洲40a的人口变化与LULC变化的时空动态关系,探讨人口空间变化对LULC变化的驱动作用。结果表明:1)40 a来,克里雅绿洲的扩张表现在:人口显著增加,坤长14.277 7万人并向县、乡、镇中心集聚,建设用地与耕地向南部扩张明显,林地增加但趋于破碎化,草地与水域锐减。2)人口的空间变化是克里雅LULC变化及绿洲扩张的直接驱动力,直接表现为建设用地与耕地向南扩张,间接表现为林地变化、草地变化、水域变化。人口的空间变化对绿洲扩张的内部驱动作用,与绿洲北部恶劣的自然环境、克里雅河自南向北的流向共同作用,导致绿洲向南部扩张。3)地理加权回归模型能够反映更多的异质特征。在总体相关结果下,局部区域可能出现方向相反或大小不等的相关结果。研究可为当地政策制定提供依据。

       

      Abstract: 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.

       

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