Objective  Located in southeast Nanjing, Jiangning District has a variety of landforms and typical northern subtropical climate and vegetation characteristics. With the transformation of land by urban construction and agricultural production, Jiangning District, as an urban fringe of Nanjing, has experienced the disturbance of its natural ecological background and the change of its ecological environment, making it urgent to address such issues as habitat fragility and biodiversity conservation.

Methods  This research explores the identification, protection and planning of rural ecological space in Jiangning District concretely and meticulously by the research approach of generating qualitative decision-making based on quantitation and positioning. Firstly, based on the remote sensing interpretation of land cover types in Jiangning District, the research analyzes the types of rural habitats and the distribution of the ecological, and living production production spaces. Secondly, the research adopts the MSPA method (focusing on landscape morphology) and the InVEST model (focusing on habitat quality) to integrate ecological and morphological factors and extract ecological sources in combination with the ecological, production and living spaces and habitat types. Thirdly, the research adopts the raster calculator of ArcGIS to obtain the comprehensive ecological resistance surface in the research area, and adopts the Linkage Mapper toolbox of ArcGIS to identify ecological corridors, pinch points and obstacle points, finally forming a multi-level ecological network consisting of ecological source sites, inter-source ecological corridors and ecological nodes, based on which the research explores a spatial optimization strategy targeting rural biodiversity conservation.

Results  The ecological spaces in Jiangning District are mainly located in areas with hilly landscape, which have a high vegetation cover and are important spaces for ecological conservation; the living spaces are mainly located in the central plains with a relatively flat topography and along the Yangtze River where village settlements are mainly scattered in the southern area; the agricultural production spaces such as arable lands and fish ponds are mainly distributed in the form of mosaic together with village settlements. These three types of spaces together form the rural ecological landscape pattern of Jiangning District. The habitat types in Jiangning District can be divided into three types: artificial habitat, semi-natural habitat and natural habitat. Specifically, the artificial habitats mainly include 532.42 km² of construction lands, 99.03 km² of bare lands, some grasslands, and several artificial pits and reservoirs. The natural habitats mainly include the woodlands in the hilly areas and the water and coastal wetlands of the Yangtze River, the Qinhuai River, the Lishui River and the Jurong River. In total, there are 582.78 km² of woodlands, 40.59 km² of grasslands and 164.01 km² of waters in the research area. A multi-level composite habitat network pattern of four zones, five groups, multiple corridors and multiple nodes in Jiangning District is further integrated as the basis for building the ecological base of the regional countryside. The ecological source sites are divided into three categories: ecological wetlands, natural mountain forests and country parks. The Yangtze River wetlands in the northwest of the Yangtze River basin are habitats for a variety of organisms, where the wetland resources need to be fully protected, the ecological quality of the water environment improved and the synergistic protection of blue and green spaces emphasized. As to natural mountain forests, it is supposed strictly control the ecological boundaries between natural mountain forests and natural scenic areas, and maintain low-intensity intervention with a focus on ecological conservation. The artificially created country park green spaces should be developed and protected in a low-impact manner, with the use of surrounding lands being controlled to safeguard the blue-green ecological base and serve the inhabitation of a variety of organisms. The ecological corridors can be divided into natural ecological corridors and integrated ones. The natural ecological corridors are dominated by ecological spaces, the original habitat resources of which should be well maintained. The integrated corridors mainly pass by production and living space. For the integrated corridors, the ecological obstacle points should be treated as ecological restoration points, and relevant measures should be taken to preserve, improve and rebuild the ecological restoration points. The ecological pinch points should be treated as ecological protection points, and on the basis of reasonable control of development intensity, the ecological attributes of the ecological pinch points should be preserved or the habitat quality of the nodes should be improved to enhance the regional habitat connectivity.

Conclusion  The optimization of rural ecological landscape and habitat networks needs to be based on the spatial synergy of the ecological, production and living spaces, and in case of any conflicts or contradictions between the current land use and ecological key locations, the scope of basic agricultural land and the ecological red line need to be strictly protected. This research integrates and delineates habitat networks based on relevant quantitative and spatial positioning studies, with a view to improving the accuracy of habitat conservation planning. With the popularization of sensors and IoT applications, data and information can be made more real-time through collecting dynamic data in real time to reflect the conditions of the rural ecological environment, which can not only enhance the timeliness of research, but also make the protection planning of the ecological environment much more scientific.