宁夏中部干旱带生态移民过程生态风险时空分异——以红寺堡区为例

生态移民过程具有规模性、集中性等特点，其对安置区土地利用产生最直接的变化，理论上具有显性或潜在的生态风险。以我国最大的生态扶贫移民集中区-宁夏红寺堡区为例，以1995年、2005年和2015年三期遥感数据为基础，综合运用景观格局指数、生态风险指数、空间分析法构建生态风险指数，利用ArcGIS空间分析功能对研究区生态风险的时空变化特征进行分析。结果表明：1995-2015年间安置区景观格局发生较大的变化，草地面积减少29 744.04 hm²，耕地、林地、水域以及建设用地面积分别增加了18 979.73、4 167.343 6、672.193 3、4 314.280 6 hm²，沙地和未利用地变化幅度较大，但其研究始末面积变化不大。研究区景观生态风险空间分布变化明显，且呈现出由集中连片式分布转向零散式的多核地域分布的变化格局，其中高度风险区主要分布在柳泉乡的东北角、小罗山西麓地区以及大河乡的中部和西南部，较高风险区在安置区北部地区以及大河乡的中西部地区分布较为广泛，较低和低度风险区则主要分布在罗山周边地区、柳泉乡的东南部、太阳山镇的西南部以及红寺堡镇的南部等地区。研究期间安置区高生态风险区面积大幅度减少，较高风险区和低度生态风险区面积不断增加，因此生态风险总体呈减弱趋势。安置区生态风险值呈现出显著的空间正相关关系，在空间上存在着空间集聚效应，说明安置区生态风险时空分布与人类活动、土地利用强度之间关系密切。

Spatial and temporal variation of ecological risk in the process of ecological immigration in the arid zone of central Ningxia:A case of Hongsibu District

The ecological immigration process is characterized by the scale and concentration,and it produces the most direct changes to the land use in the resettlement areas,theoretically having explicit or potential ecological risks.Taking the Hongsibu District at central Ningxia Province,the largest ecological poverty alleviation and immigration area in China,as an example,the temporal and spatial characteristics of ecological risk in the study area was analyzed based on the remotely sensed data from 1995,2005,and 2015,using the landscape pattern index,ecological risk index,and spatial analysis method to construct an ecological risk index.The results showed that the landscape pattern of the resettlement area was changed greatly from 1995 to 2015,the area of grassland was decreased by 29 744.04 hm²,and the area of cultivated land,forest land,water area and construction land were increased by 18 979.73 hm²,4 167.343 6 hm²,672.193 3 hm² and 4 314.480 6 hm² respectively.Although the change range of sandy land and unutilized land during the research period is quite large,the area of the study area has little change;the spatial distribution of landscape ecological risk in the study area has been changed obviously,and it shows a shift from concentrated contiguous distribution to scattered multi-nuclear geographical distribution.The high-risk areas are mainly distributed in the northeast corner of Liuquan Township,the western foot of Xiaoluoshan and the central and southwestern areas of Dahe Township.The higher-risk areas are distributed in the northern areas of the resettlement area and the central and western regions of Dahexiang.While the low and lower risk areas are mainly distributed in the surrounding areas of Luoshan,southeast of Liuquan Township,southwest of Sun Town and Hongsibu town in southern areas.During the study period,the conversion rate of different types of risk areas in Hongsibu Ecological Resettlement Area was rapid,among which,the area of high ecological risk areas was decreased significantly while the area of high-risk areas,low-risk areas and low-level ecological risk areas kept being increased.Therefore,overall,the risk is weaker.The ecological risk value of the resettlement area shows obvious spatial positive correlation,and there is a significant spatial agglomeration effect in space,indicating that the spatial-temporal distribution of ecological risk in the resettlement area is closely related to human activities and land use intensity.