The Ecological Risk Pattern Of Jiangsu Coastal Area Based On Land Use Change

Land is the main space carrier of human life and an important natural resource that affects the survival and development of human beings,animals and plants.Land use change in a certain area is regarded as the source of regional ecological risk change.In order to assess ecological risk caused by land use changes in the region of economy developing rapidly,based on remote sensing data of land use in Jiangsu coastal areas in 1990,2000,2010 and 2015,this paper analyzed the land use changes and its transformation quantitatively supported by GIS.Meanwhile,the paper built ecological risk index based on the landscape disturbance index and vulnerability index,and then the spatial and temporal dynamic changes of landscape ecological risk are quantitatively evaluated by using geostatistical analyst and spatial autocorrelation analysis.The results show that:(1)From 1990 to 2015,the overall trend of land use change in the region was the decrease of arable land,grassland and the forest,with the largest decrease in cropland.The area of construction land,waters and unused land increased,with the largest increase in construction land.The cropland is mainly converted to construction land,and its main supplementary source is grassland.The supplementary construction land is mainly derived from cultivated land,and the construction land is mainly converted into water area.In terms of spatial distribution,land use change mainly occurred in the coastal areas of Yancheng and Nantong and the eastern area of Lianyungang.(2)By comparing the inflection point of sensitive landscape pattern index,the optimum granularity of landscape pattern study in coastal areas of Jiangsu Province was determined to be 50 m.From 1990 to 2015,the landscape fragmentation index and splitting index of cropland,forest,grassland and waters was increasing,while the landscape fragmentation index and splitting index of construction land and unused land was decreasing.(3)The results showed that the ecological security of Jiangsu coastal areas had improved,and the average ecological risk value of the entire region decreased from 0.1563 in 1990 to 0.1529 in 2015.As far as spatial distribution is concerned,the ecological risk intensity of the study area decreased gradually from the inland to the coastal areas,and the risk grade showed a zonal distribution.In recent 25 years,the moderate ecological risk areas covered the biggest area of the study area,and the lower ecological risk areas showed a tendency of expansion.The higher ecological risk areas were mainly distributed in the cultivated land of southwestern region and the waters of western region of the study area,and its area increased first and then decreased.Between 2010 and 2015,low ecological risk areas appeared in the northeast of the study area.The total area of the ecological risk grade reduction was much larger than the area of the risk grade increased.Grade reduction zone of ecological risk were mainly concentrated in the higher ecological risk area,moderate ecological risk area and the lower ecological risk area,while grade increase zone of ecological risk were mainly concentrated in the lower ecological risk area and moderate ecological risk area,that is,grassland and waters of eastern region of the study area and cropland of southwestern region,and the main reason was the rapid development of port industry and new coastal town resulted in the intensification of land use change,which caused the balance of ecosystems being damaged.In the process of ecological risk grade transformation,the area from middle ecological risk grade to the lower risk grade is the largest.The overall spatial difference of ecological risk index in the study area had increased,showing the high-high aggregation and low-low aggregation in local area.The area of high value aggregated mainly gathered south along the western boundary of the study area,the low value aggregation region was mainly distributed in the northeast of the study area and the eastern coastal areas.(4)Cropland,waters and construction land were the main sources of ecological risk in the study area.The ecological risk contribution rates of waters and construction land were increasing,while the ecological risk contribution rate of cultivated land was decreasing.Meanwhile,the region with cropland as the main ecological risk source includes Dongtai,Haian,Rudong,Rugao,Tongzhou,Haimen and Qidong.The region with construction land as the main ecological risk source includes Lianyungang,Xiangshui and Nantong.The region with waters as the main ecological risk source includes Ganyu,Guanyun,Sheyang and Jianhu.Finally,combined with the study results,several ecological risk management measures are put forward in order to provide scientific theoretical basis and reliable technical support for the realization of land sustainable utilization,promoting the coordinated development of land use and environment protection,and the policy making of ecological risk management.