Analysis Of Spatiotemporal Driving Force And Spatial Heterogeneity Of Coastal Wetlands In Dalian

Wetlands is the ‘Kidney of the earth',which are known as by human beings.It is an extremely significant water conservation area,nutrient retention area and the habitat of a great number of the endangered animals and plants on the earth.At the same time,it can also play the vital role of water storage,flood regulation,environmental purification and climate regulation,which is called a natural ‘Sponge'.Coastal wetland,as a transitional zone between land and sea,which is the primary habitat of aquatic benthic organisms because of its vast oxygen-rich area affected by intertidal zone.With the population growth and social and economic development,the global wetland area is decreasing in recent years,while the coastal wetland area is more seriously deteriorating.Wetland reclamation,land reclamation,urbanization and expansion lead to serious destruction of coastal wetlands.They are the vital problems to be solved urgently in coastal wetland protection,which are the decline of coastal wetland function area,the deterioration of wetland water pollution environment and the excessive use of biological resources.In July 2018,the State Council issued the Notice on Strengthening the Protection of Coastal Wetlands and Strictly Controlling the Enclosure and Reclamation,which also showed that the state paid great attention to the degradation of coastal wetlands.Dalian is surrounded by the sea on three sides,and its geographical location is unique,so the coastal wetland resources in Dalian are relatively abundant.In this thesis,it researched the status current situation and temporal and spatial changes of coastal wetlands in Dalian,and analyzed the driving factors of coastal wetlands in Dalian according to the social economic situation of each coastal town in Dalian.Geographically Weighted Regression Model can better describe spatial heterogeneity.It analyzed the dynamic changes of coastal wetlands in the study area through the heterogeneity of driving factors,so that the analysis results can provide theoretical support for the future coastal wetlands protection and refinement to the maintenance of ecological environment of each township according to their own conditions.We interpreted satellite images of six meters from coastal township administrative area to contour line in Dalian by remote sensing,and obtained the spatial and temporal changes of coastal wetland area in Dalian in this research.Combined with principal component analysis and Geographically Weighted Regression Model,SPSS17.0,Sigma plot spatial data processing software,we analyzed the main driving factors,which were affecting the change of coastal wetland area in Dalian and the direction of driving forces to different towns and the degree of influence.The results show that:The area of coastal wetlands in Dalian is continually decreasing and the landscape pattern of both natural wetlands and constructed wetlands is fragmented.The area of swamps,lakes,rivers,shallow water areas and beaches in natural wetlands is also constantly decreasing.The increasing and decreasing ranges of land use in constructed wetlands are different.The area of salt fields,nature reserves and national marine parks has increased,while the area of pens,reeds,reservoirs,ditches and paddy fields has been decreased.From 2000 to 2017,the area of natural wetlands in coastal wetlands of Dalian had always been the primary area.The natural wetland area of Santai Manchu Township in Wafangdian City and the coastal town of Zhongchang Street in Jinzhou District has been more seriously reduced,the areas where the area of constructed wetland has been more seriously reduced,which were Santai Manchu Township in Wafangdian City,Sanlibao Street in Jinzhou,Qingdui Town in Zhuanghe,Pikou Town in Pulandian and Mingyang Street.The increased area of salt fields,national ocean parks and nature reserves in constructed wetlands primarily came from the transfer of salt fields,reed fields and paddy fields.While in non-wetland areas,the increase of urban villages,industrial and mining land and traffic facilities land primarily came from the area of shallow water and beach,which contributes the most to natural wetland.The previous five principal components extracted from principal component analysis can be used to characterize the evolution of coastal wetlands in Dalian,and it accounted for 80% of the total variance.The driving forces are fixed asset investment,population,construction land scale,land-sea ratio and cultivated land area.The positive and negative correlations of the influencing factors on the size of coastal wetlands in different regions were different,and there were also differences in spatial distribution.Among them,the cultivated land area,the fixed asset investment and the land-sea ratio are positively correlated with the size of coastal wetlands.The relationship between population factors and the size of coastal wetlands was positive and negative.The increase of construction land scale had been a negative effect on the size of coastal wetlands.Combining with the change situation of spatial heterogeneity of coastal wetlands in Dalian,this thesis put forward corresponding countermeasures and suggestions from two aspects of artificial wetlands protection and natural wetlands protection according to local conditions,so as to embody the ecological concept that lucid waters and lush mountains are invaluable assets,and realize the sustainable development of natural environment.