Spatio-temporal Reconstruction In Redeveloping Inefficient Land From The Perspective Of Ecological Niche

China advocates that economic development must be of high quality and high efficiency.In the past 30 years,built-up areas of most cities in China did not pay more attention to the improvement of land-use efficiency in the early stage of urban expansion,inefficient land has therefore become one of the uneconomic manifestations.How to redevelop inefficient land and improve urban land-use efficiency has become a hot issue in China's economic development at the present stage.Under the background of new urbanization,many scholars have studied the theories and methods of reconstructing the material space and ecological space on the inefficient land,hoping to improve its comprehensive utilization efficiency.However,on the one hand,most studies focus on reconstructing the space of one functional orientation,dose not reflect the price paid by a kind of functional space when it occupies the space of another function.One the other hand,in the micro area,how the elements link to each other,in what way to link elements to each other better,remains to be further deeped in the redevelopment process.To guide urban constructors to obtain reasonable socio-economic benefits without the unreasonable “occupation” of ecological space during the redevelopment of inefficient land,so as to realize the "rebirth" and "symbiosis" of the internal material and ecological space of the inefficient land,this study selected urban district of Zhanjiang,which is an area in rapid urbanization development stage,as a case,to propose the theoretical framework and technical system for balancing the spatial pattern between land for sosio-economic function and land for ecological function in inefficient land,based on analyzing the economic and ecological characteristics in inefficient land,in the detailed planning phase,from two dimensions of time and space.First,double-aspects method was proposed to identify the spatial pattern of inefficient land in study area.Then standard deviation ellipse,kernel density and spatial autocorrelation model were used for analyzing the characteristic of position,direction,agglomeration,dependence and dispersion for all the inefficient land.To analyze the formation of the spatial pattern of inefficient land,the binary logistic regression model was used to identify the factors.Accordingly,the objects for spatio-temporal reconstruction were acquired.Second,to quantize the natural-ecological niche,economic-ecological niche,and natural-economic-ecological niche in every inefficient land,ecological niche model was constructed.Third,taking the natural-economic-ecological niche in inefficient land as the core parameter,and setting the goal of balancing the spatial pattern between land for socioeconomic function and land for ecological function,with certain constrains,to implement the spatial reconstruction of inefficient land.Accordingly,seeing the natural-economicecological niche as “pressure”,combing with analysis of “thrust”,“force of friction”,and “support force” in promoting the redevelopment of inefficient land,the timing optimization model was proposed to determine a reasonable time sequence for the redevelopment of each inefficient land.Finally,the objectives and principles of redeveloping inefficient land were set to propose the modes the policy suggestions of redeveloping inefficient land.The main conclusions of this study are as follows:(1)The total amount of inefficient land in study area accounts for 12.12% of the study area.The distribution direction of low-efficiency construction land is consistent with the trend of important main roads in the research area,and the overall low-efficiency shows a trend of weak centripetal and discrete edges,as well as a trend of overall discrete and locally dependent distribution.In addition,the closer to the administrative centers of the four subdistricts of the study area,the higher the kernel density of the inefficient construction land.Current land use status,land ownership,building volume and average building storey were found connected factors for the formation of inefficient land.The main cause of inefficient land was: The land use efficiency in the early stage or the current land use mode that can meet people's production expectations cannot meet people's expectations in the short and medium term when the macro-social and economic development goals change.The land-use efficiency changed from high to low in subjective or objective efficiency indicators.In economics,it can be interpreted as "the marginal benefit of land allocation between different land-use types and locations is not equal" and "the intensity of land redevelopment does not meet the requirement that marginal benefit equals marginal cost".(2)By comparing natural-ecological niche,economic-ecological niche and naturaleconomic-ecological niche,natural-ecological niche in inefficient land showed the trend of marginal distribution and Interactive distribution;the economic-ecological niche was distributed axially and diffuses outward from the center.Also,there is a negative correlation between natural-economic-ecological niche and economic-ecological niche,which is basically consistent with the niche differentiation theory.Accordingly,the inefficient land in the central area should improve the socio-economic functions,while the rest areas should reduce the socio-economic functions and carry more ecological functions.(3)By establishing the ecological niche model,seeing natural-economic-ecological niche as core parameter in redeveloping inefficient land,urban constructors can be guided to redevelop more land for ecological function in inefficient land,so as to improve urban environment.Also,more inefficient land around the city can be guided to redevelop more land for socio-economic function to support the overall socio-economic development goals.Reconstructing the spatial pattern according to the natural-economic-ecological niche in inefficient land,may lose a small amount of certain economic value,but can improve the ecological benefits through expanding the area amount of land for ecolocical function in inefficient land,which may can make up for the loss of economic benefit caused by the decrease of land for socio-economic function to a certain extent.Finally,reconstructing the spatial pattern of inefficient land based on its natural-economic-ecological niche,dose not contradict the current usban land-use pattern,but enables the land-use types after the redevelopment of inefficient land,which was help to achieve the highest and best land-use modes from the micro scale(4)In the process of eatablishing “pressure – trust-force of friction – supporting force”(PTFS)system to optimize the time sequence of inefficient land,natural-economicecological niche was regarded as “pressure”,which may not affect the normal time sequence of redeveloping inefficient land.On the contrary,it is beneficial to balance the spatial pattern between land for socio-economic function and land for ecological function in every inefficient land and study area,so as to support the realization of social and economic development goals and ecological and environmental protection goals.The main reason is that "thrust" and "force of friction" play a leading role in the implementation of the redevelopment of inefficient construction land,and "pressure" and "supporting force" are only influential factors in adjusting "thrust" and "friction".(5)On the basic of analyzing the results of spatio-temporal reconstruction in redeveloping inefficient land,three modes for redeveloping inefficient land was proposed including "reverse planning" model,"forward planning" model,"reverse planning first,then forward coordination" model,and "quality improvement" model.Effective "incentive" and "control" measures will facilitate the implementation of the spatial and temporal reconstruction of the redevelopment of inefficient land from the perspective of ecological niche.(6)The results,of spatio-temporal reconstruction in redeveloping inefficient land,from the perspective of ecological niche,are reasonable.The viewpoints and conclusions of the study are conducive to guiding and studying the urban central areas with similar location conditions,which hope to promote economic development and improve the ecological environment at the same time through redeveloping inefficient land.