干旱高原湖泊湿地土地利用变化与驱动因素分析——以泊江海子湿地闭流区为例

鄂尔多斯高原湖泊湿地土地利用变化及生态趋势研究,可为干旱区资源管理、环境保护和生态规划提供科学依据和决策支持。基于Landsat卫星系列影像及气候数据,采用支持向量机(SVM)方法对1986—2019年的16期影像进行监督分类,通过变化检测、叠加分析,获得土地利用转移矩阵及各土地利用类型空间变化,定量描述了不同时段土地利用数量及空间转化特征。结果显示:(1)研究期间裸地、低覆盖度草地和高覆盖度草地是流域主导土地利用类型,占整个研究区的93%～99%,水体、建设用地及林地在总体面积中所占比例很少,分别为1%,1%和2%;(2)34年间土地利用状况发生了较大的变化,主要表现为裸地、水体面积减少,低覆盖度草地、高覆盖度草地、林地和建设用地面积增加,其中建设用地面积增幅最大,增加了44.3倍;(3)研究区土地类型的转换主要发生在裸地、低覆盖度草地、高覆盖度草地之间,裸地转入转出主要为低覆盖度草地,总体转出速度高于转入速度,裸地面积大幅减少31.79%,低覆盖度草地分两个阶段持续转化为高覆盖度草地,使高覆盖度草地占比从14.63%增加到35.98%。(4)受气候变化和人类活动共同影响,研究区土地利用变化剧烈,且人类活动影响占主导地位。

Analysis on Land Use Change and Driving Factors of Lake Wetland in Arid Plateau-A Case Study on the Inflow Area of Bojianghaizi Wetland

The study on land use/cover changes and ecological trend of lake wetland in Ordos Plateau can provide scientific basis and decision support for resource management,environmental protection and ecological planning in arid areas.Based on the series of Landsat satellite images and climate data,16 scenes from 1986 to 2019 were captured and classified by the support vector machine(SVM)supervised classification method.Through change detection and overlay analysis,the land use conversion matrix and spatial change of each land use type were obtained,and the quantity of land use and the characteristics of spatial conversion in different periods were quantitatively described.The results show that:(1)bare land,low-coverage grassland and high-coverage grassland,accounting for 93%~99%of the whole study area,were the dominant land use types in the basin during the study period;the proportions of water body,built-up land and forest land were very small,which were about 1%,1%and 2%,respectively;(2)during the past 34 years,great changes had taken place in the land use situation including the reduction of bare land,water body,and the increase of low-coverage grassland,high-coverage grassland,woodland,built-up land;the increase of the construction land was the largest,the construction land increased by 44.3 times;(3)the conversion of land types in the study area mainly occurred among bare land,low-coverage grassland and high-coverage grassland;bare land which in total reduced 31.79%was mainly converted into and out of low-coverage grassland,and the overal l outgoing rate was higher than incoming;the low-coverage grassland was converted into high-coverage grassland,which increased the proportion of high coverage grassland from 14.63%to 35.98%;(4)jointly influenced by climate change and human activities,the land use in the study area had changed dramatically,and the impact of human activities was dominant.