西北旱区土地利用变化的时空异质性研究——以陕西铜川耀州区为例

Spatio-temporal heterogeneity of land use changes in northwest arid region:a case study of Yaozhou District,Tongchuan,Shaanxi

【目的】从土地利用变化程度、过程及空间转移3个维度揭示西北旱区典型县域土地利用时空变化过程及特征,为区域土地政策的制定与实施提供参考依据。【方法】以陕西铜川耀州区为例,用2000年5月、2008年7月以及2015年8月的Landsat遥感影像为主要数据源,根据土地资源及其利用、自然属性状况,将研究区土地利用类型共分为7种(林地、耕地、草地、农村居民点、城镇用地、其他建设用地和水库坑塘),采用土地利用程度指数、土地利用转移矩阵和土地利用重心迁移模型,分析2000-2015年陕西铜川耀州区主要土地利用类型的时空格局变化特征。【结果】(1)从利用程度来看,2000,2008及2015年耀州区土地利用程度综合指数依次为252.65,247.69和250.66,其中2000-2008年耀州区土地利用程度变化量为-4.97,处于调整期;2008-2015年耀州区土地利用程度变化量为2.97,处于发展期;2000-2015年,耀州区土地利用程度变化量为-2.00,土地利用总体处于调整期,仍有较大开发利用空间。2000-2015年,耕地利用程度变化量间呈持续下降趋势,开发利用水平较低,呈衰退趋势;林地利用程度变化量先上升后下降,总体呈持续发展趋势;而农村居民点、城镇用地及其他建设用地的利用程度变化量则呈持续增长趋势,处于发展阶段;水库坑塘和草地的利用程度变化量呈先下降后上升趋势。(2)从转移过程来看,在2000-2008和2008-2015年耀州区不同土地利用类型之间发生转移的面积分别为23 362.44和21 579.20 hm^(2),其中耕地和林地发生转移面积占总转移面积的比例均最高,其次是农村居民点用地、草地、其他建设用地和城镇用地,水库坑塘转移面积占比最小;各土地利用类型均进行了一定程度的相互转移,其中耕地与林地相互转化以及耕地向农村居民点、其他建设用地和城镇用地转化成为主要趋势。(3)从空间变化来看,在2000-2015年,耀州区各土地利用类型重心均进行了一定程度的空间迁移,其中其他建设用地和草地的重心转移距离均较大,林地的重心转移距离最小。【结论】2000-2015年陕西铜川耀州区土地利用变化存在明显的空间分异特征,土地利用格局演变加速。

【Objective】 This study revealed the process and characteristics of spatial and temporal land use changes in typical counties in the northwest dry area from three dimensions of land use change degree,process and spatial shift to provide basis for the formulation and implementation of regional land policies.【Method】 Taking the remote sensing images of Landsat from May 2000,July 2008 and August 2015 as the main data sources,the land use types in the study area were divided into seven types(forest,cultivated land,grassland,rural settlement,urban land,other construction land and reservoir ponds) based on the status of land resources and their utilization and natural attributes.Land use degree index,land use transfer matrix and land use center of gravity migration model were used to analyze the characteristics of spatial and temporal pattern changes of major land types in Yaozhou District,Tongchuan,Shaanxi from 2000 to 2015.【Result】(1) The comprehensive indexes of land use degree in Yaozhou District were 252.65,247.69 and 250.66 in 2000,2008 and 2015,respectively.The amounts of change of land use degree were-4.97,2.97 and-2.00 from 2000 to 2008,2008 to 2015 and 2000 to 2015,indicating adjustment period,development period and adjustment period,respectively.There was still room for development and utilization.From 2000 to 2015,the changes in use of cultivated land showed a continuous decline trend with low development and utilization levels.The change in use of forest land increased and then decreased,with a continuous development trend.The changes in use of rural settlements,urban land and other construction land increased continuously and remained in the development stage.The changes in utilization of reservoirs,ponds and grasslands were decreasing first and then increasing.(2) The areas transferred between different land use types in Yaozhou District from 2000 to 2008 and from 2008 to 2015 were 23 362.44 and 21 579.20 hm^(2),respectively.Cultivated land and forest accounted for the highest proportion,while reservoirs and ponds accounted for the smallest proportion.All land types transferred to other types and main trends included mutual transformation of cultivated land and forest and transformation of cultivated land to rural settlements,other construction land and urban land.(3) From 2000 to 2015,all land types in Yaozhou District had spatial migration,with largest shifts in other construction land and grassland and smallest shift in forest land.【Conclusion】 Land use changes in Yaozhou District,Tongchuan,Shaanxi had significant spatial divergence characteristics from 2000 to 2015,and the evolution of land use pattern was accelerating.