| The rapid development of urbanization has exacerbated the conflict between human activities and ecosystems,which has a negative impact on the ecological environment and also seriously threatens the ecological security and sustainable development of the region.The construction of ecological security pattern(ESP)can effectively alleviate many ecological and environmental problems caused by rapid urbanization and unreasonable use of land,and is an important way to alleviate the contradiction between regional socio-economic development and ecological protection.This research takes Fengxian District in Shanghai which is in the process of rapid urbanization as the study area,and adopts the mainstream research paradigm of"identifying ecological sources—constructing ecological resistance surfaces—extracting ecological corridors"to carry out the construction and optimization of the ESP of Fengxian District.Taking high-resolution remote sensing image and land use spatial data of Fengxian District as key data sources,this study combines with field survey,regional socio-economic data and related development policies to explore the spatial distribution change characteristics of land use and landscape pattern in Fengxian District from 2010 to 2018 and its potential connection with social development.Considering the importance of ecosystem service functions,this paper conducts a quantitative evaluation study on ecosystem service functions in Fengxian District from four aspects:supply service,regulation service,support service and cultural service,and identifies the area with high value of ecosystem service functions as the ecological sources.On this basis,the minimum cumulative resistance model is used to identify the ecological corridors,then combining with the ecological sources,the ESP of Fengxian District in 2018 is constructed.Finally,based on the land use contradiction reflected by the spatial change characteristics of land use and landscape pattern,combined with the ecological background characteristics of Fengxian District,this study explores the optimization strategy of regional ESP in the context of ecological civilization construction from the aspects of patches,substrates and corridors,so as to provide effective space guidance and basic space approach for the development and construction of green ecological livable city in Fengxian District and the protection of regional ecological safety.The main conclusions of this study are as follows:(1)The land use types of Fengxian District were mainly cultivated land,construction land and water area.In 2018,the three types of land accounted for 82.35%of the total area.The overall transfer characteristics of land use between 2010 and 2018were the increase of artificial and greenland ecosystems,and the reduction of wetlands and agroforestry ecosystems.With the construction and improvement of urban parks in the past eight years,the green land ecosystem had the highest dynamic change and the fastest growth rate(37.41%),with a total increase of 7.24 km~2.Construction land was next(7.1%),but the area had increased by nearly 1.57 times,and the total area had increased by 77.47 km~2.Among them,the growth rate of artificial residence had reached as high as 40.6%during the past eight years,which reflected the rapid urbanization development.(2)In 2018,the cultivated landscape area was the largest in Fengxian District,and the landscape types with high levels of ecological service functions,such as water,forest and green space accounted for a relatively low proportion(20.61%).The construction area had the largest number of landscape patches and the highest LPI(Largest Patch Index)value,which was the most dominant landscape in Fengxian District;however,the dispersion among patches was relatively high,and the characteristics of artificial surface expansion and fragmentation were obvious.From2010 to 2018,the forest landscape area had increased,but the fragmentation degree of patches had deepened,indicating that the distribution of forest landscape was unreasonable and the landscape construction lacked overall planning.In the past eight years,the land use pattern in Fengxian District had gradually enriched,but the overall landscape fragmentation degree had increased,and the rationality of landscape composition and distribution had declined.The land use pattern had gradually developed towards a single fragmentation direction,which had the characteristics of typical landscape evolution in the process of rapid urban construction.(3)In Fengxian District,the proportion of the area with high-value ecosystem services in 2018 accounted for only 8.24%of the entire area,and the overall level of ecosystem services in the region was low.The area with high quality of ecosystem service functions was distributed in a fragmented belt along the northwest-southeast direction,and the land type was mainly forest land.Patches with sub-optimal service functions were mainly park greenbelts and tidal flat wetlands,which were mostly located in suburban buffer zones.The low value area of service functions was mainly used for construction and was mostly located in the urban built-up area dominated by human activities.The spatial distribution of ecosystem service functions has a strong negative correlation with the degree of regional urbanization.(4)In this study,the present situation of ecological security pattern space in Fengxian District is identified as three horizontal and five vertical in 2018.There were a total of 13 ecological sources in the pattern,which were mostly composed of large-area forest lands with high levels of ecological service functions.The total area of the sources area was 24.04 km~2,accounting for 3.36%of the study area.There were 22ecological corridors with a total length of 249.69 km,which were mainly distributed radially along the facility woodland and road shelterbelt in the whole area.In the ESP in 2018,the spatial distribution of the ecological sources were not uniform and the corridor connection was relatively weak.Some corridors were too long,and the total ecological corridors were less networked.The radiation range of the ESP had not covered the entire area,so it cannot meet the ecological security needs of the whole region for the time being.(5)Based on the current ESP of Fengxian District and the characteristics of regional ecological background,this research optimize the ESP of Fengxian District from the aspects of improving the quality and quantity of ecological sources,optimizing ecological corridors,identifying ecological nodes and key ecological restoration areas.In this study,a total of 9 new ecological sources(area of 5.63 km~2)were added,an increase of 23.42%compared with the existing source area;29 new corridors were optimized and the total length of corridors increased to 567.69 km;identified the patches corresponding to the intersections of ecological corridors and the small existing ecological lands with and high ecosystem service functions in the corridor paths as the ecological nodes;finally combined with five key ecological control areas including Zhelintang Landfill to form the optimized ESP of Fengxian District.The optimized pattern resembles an arch and forms a closed-loop structure in the whole region,which realizes the stable continuity of regional ecological functions and ecological processes,and provides an effective spatial approach for maintaining the sustainable development and ecological safety of regional ecosystems. |
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