Assessing method for regional ecological connectivity and its application based on GIS

Abstract: Rapid urbanization has caused fragmenting and isolating ecological landscape, which may have led to biodiversity loss and threatened land ecological safety. Therefore, assessing the impact of rapid urbanization on ecological connectivity has become an inevitable choice for biodiversity protection and the maintenance of regional ecological security as well as providing decision support for land planning.Based on the second national land survey data and general land use planning data, a GIS-based iterative topological analysis method was used to identify the ecological functional areas according to the type of the land use in the Caofeidian new district. Eight categories of ecological functional areas with a total area of 142 798.30 hm2 were identified, which accounted for about 72.19% of the study area. With the cost distance model, the Barrier Effect Index (BEI) and Ecological Connectivity Index (ECI) were used to assess the impact of landscape ecological connectivity on current land use scenario and land planning scenario in the Caofeidian new district to evaluate the driving mechanism of the deterioration of ecological landscape, to assess the impact on the ecological function relationship of ecological lands, and to provide recommendations. The results show that the area whose Ecological Connectivity Index was above medium level only accounts for 56.45% of the total area of the Caofeidian new district, the regional ecological function area has been distinctly fragmented and isolated, while the non-connectivity area, whose Ecological Connectivity Index equals 1, has showed stronger connectivity of spatial distribution, such regional landscape ecological deterioration was mainly caused by the expansion of construction land and insufficient attention to ecological protection in land use planning.Further analysis of overlaying the ECI index maps of future scenarios based on urban growth and the current situation was conducted. Results of impact on the Ecological Connectivity Index indicated that, of the planning new urban and industrial lands of 7 714.71 hm2, 2 027.25 hm2 of that has been identified to have a critical impact on ecological connectivity. It indicated that, instead of construction land, such area should be planned for ecological land, and protection measures are necessary to improve the ecological function. However, a number of areas, about 4 338.63 hm2 in total, most of which are adjacent to existing urban areas, had minimum impact on the ecological connectivity. Such areas might be considered suitable for construction land, whereas the remaining 1 348.83 hm2 with medium impact to ECI could be considered suitable for construction land under the premise of maintaining ecological corridors.Three effective ways were suggested to increase Caofeidian new district's ECI and improve the ecological structure: strengthen the protection of important ecological functional lands having obvious influence on the regional ecological connectivity index during the preparation of general land use plans; reconstruct the ecological landscape using residual ecological resources to improve the ecological connectivity level; and strengthen the green network construction in the build-up area.