Research For Analysis And Constructing Green Infrastructure Network Based On Spatial Prioritization In Zhengzhou

Green infrastructure is an important natural life support system of the city,which includes all kinds of ecological spaces in the city,as well as gray-green mixed infrastructure with traditional infrastructure,buildings and structures.With the rapid development of urbanization and the evolution of urban spatial pattern,a series of ecological environment problems and social equity problems have emerged in developing cities.Green infrastructure has become a hot research topic in various cities and disciplines to deal with environmental disaster risks and the unfair distribution of social resources faced by cities with nature-based solutions.Taking Zhengzhou City in Henan Province as an example,this paper,based on systematically sorting out the theories related to green infrastructure and ecosystem services,clarified the general situation of urban development and the current situation and causes of ecological environmental problems in Zhengzhou,and formed a research approach of green infrastructure by "priority selection,adaptation to nature,consideration of coexistence,integration and adaptation" based on spatial priority.Taking the ecological environmental disasters brought by urbanization in Zhengzhou as the breakthrough point,from the perspective of the research on the matching of ecosystem services supply and demand,this paper divides the spatial structure of three types of Zhengzhou,constructs the priority evaluation system respectively,and proposes the optimization construction strategy of green infrastructure network and the implementation control suggestions.(1)The spatial structure of Zhengzhou was divided and the characteristics of green infrastructure in different spaces were analyzed.Firstly,by comparing the land use distribution of Zhengzhou in 2020 with the administrative division boundary and actual administrative jurisdiction boundary of Zhengzhou,it is concluded that the research on the green infrastructure of Zhengzhou needs a more accurate and scientific spatial division that is more line with the actual land use characteristics.Secondly,seven types of data that can represent land use and social economy were selected as influencing indicators to divide the spatial structure scope of Zhengzhou.Combined with the neural network operation model,Zhengzhou was divided into urban core area,urban fringe area and urban outer edge area.Among them,the urban core area is about 453.93km2,accounting for 6.04% of Zhengzhou,the urban fringe area is about 901.48 km2,accounting for 11.99%,and the urban outer edge area is about 6162.88km2,accounting for 81.97%.Finally,Based on MSPA to identify,extract,classify and characterize the land for land for green infrastructure in Zhengzhou.The green infrastructure in the urban core area is about 67.17 km2,which only accounts for14.96% of the total area and 1.47% of the green infrastructure land in Zhengzhou.The green infrastructure in the urban fringe area accounts for 30.54% of the total area but only accounts for 6.83% of the green infrastructure land in Zhengzhou city,with patch areas ranging from0.01 km2 to 2.83km2.The green infrastructure in the urban outer edge area is about 4203.86km2,accounting for 69.13% of the total area and 91.7% of the GI land in the whole study area.The distribution characteristics of green infrastructure in the three types of urban space are different,which further confirms the necessity of the spatial division of Zhengzhou to study green infrastructure.(2)Based on the disaster risk assessment framework,five regulation services(air purification,stormwater regulation,temperature regulation,hydrology regulation,and CO2 emission regulation)and one cultural service(recreation service)are selected as evaluation indexes to construct the evaluation system of ecosystem services demands in the urban core area.From the single evaluation results of the six services,the additional demand for air purification,stormwater regulation,and temperature regulation services is level 5 in Beixia Street,Nanguan Street,and Hanghai East Road blocks.The level 5 blocks of hydrological regulation include Shuangqiao,Wutong,Yingbin Road and Yangjin Road blocks.There are26 blocks in level 5 in the additional demand assessment of CO2 emission regulation.Level5 recreation service additional demand assessment blocks include West Street,Nanguan Street,and Hanghai East Road blocks.According to the comprehensive additional demand evaluation results,the weights of the above six evaluation indexes are from large to small,which are storm flood regulation(0.406),air purification(0.305),temperature regulation(0.119),recreation service(0.074),carbon emission regulation(0.073)and hydrological regulation(0.021).There are 8 comprehensive high-extra-demand blocks: Minggong Road,Jiefang Road,Dehua Street,Duling Street,Beixia Street,West Street,Nanguan Road,and Hanghai East Road blocks,which are the high comprehensive additional demand obtained from the evaluation.(3)Aiming at identifying high-value land in the urban fringe,11 evaluation indexes were selected from 5 functional units of natural ecological maintenance and urban–rural services to construct an evaluation index system of ecosystem service output.The evaluation results showed that the high-value land for natural ecological maintenance was habitat patches in the Changzhuang Reservoir area and Jianggang reservoir area,while the highvalue land patches for urban–rural services included Xiliuhu Park area,Dihu Park area,and Xianghu Ecological Wetland Park area.Level 4 and Level 5 of the above two types of ecosystem service evaluation results were selected as comprehensive high-value land,including Xushui River Park,Xianghu Ecological Wetland Park,Xiliu Lake Park,green space around Shifu Temple,Changzhuang Reservoir,Jiangang reservoir,Dihu Park,and belt green space along some rivers and traffic roads.Comprehensive high-value land is the highest spatial priority area in the urban fringe.(4)The important ecological sources and important ecological corridors on the outer edge of the city were evaluated and screened hierarchically.Based on patches’ area,biodiversity quality assessment,and landscape connectivity assessment,48 important ecological sources were selected step by step in the outer margin of Zhengzhou,and their distribution was concentrated in the Songshan Mountain area in the west and the cultivated land area in the east.The MCR model and gravity model were used to extract 73 important ecological corridors in the outer margin area,the prominent manifestation is uneven and the distance is short.The above important source areas and important corridors are the areas with the highest spatial priority in the outer edge of the city.(5)The optimal construction strategy of the green infrastructure network is put forward for the preferentially selected areas in urban core area,urban fringe,and urban outer edge area respectively of Zhengzhou,a and the integration of network space to form a green infrastructure network that spans the entire region.Firstly,the green infrastructure network optimization strategy which combines both function and structure is proposed from the block level within the priority area of the core area.Secondly,in the marginal priority area,the high-value land was supplemented and classified from the micro-habitat level,and the classification network space optimization of "forest natural habitat network","blue-green infrastructure network" and "agriculture and forestry landscape recreation network" were proposed respectively.Thirdly,the optimization strategies of important ecological sources,corridors,and nodes are proposed at the regional level to improve the level of network connectivity within the priority region of the outer region.Finally,from the perspective of overall planning,considering the integrity of priority network construction,a "three networks overlap" green infrastructure network series priority space is proposed.(6)In order to ensure the effective connection between planning strategies and practical implementation,suggestions on planning implementation and land use control are put forward.The design forms of green infrastructure networks in three types of urban space are respectively proposed: Firstly,the implementation of the core area proposes the design form of hard green infrastructure and soft green infrastructure;secondly,the implementation measures of "ecological foundation + functional compound" are put forward in the fringe area;thirdly,different construction implementation measures for the sources area and corridors be proposed of the green infrastructure network in the urban outer area,including the source area dominated by wild animals and plants and the source area with a high degree of human participation,corridors construction includes the design of linear corridors and stepping-stone corridors.In terms of land use control,a combination of rigid control and elastic guidance for planning implementation control is proposed.Under the background of increasingly severe environmental problems in developing cities,based on the planning idea of spatial priority,this paper takes Zhengzhou City as an example,divides three types of urban space,and builds the evaluation system of green infrastructure for dividing spatial priority.Based on the evaluation results,three types of space and scale green infrastructure network optimization construction strategies are proposed,and integrated to form a whole spatial priority green infrastructure network connecting the whole municipal space.This study is conducive to promoting the highquality development of urban and rural ecology and social equity in Zhengzhou and has certain reference significance for the ecological construction of other developing cities facing environmental problems.