| Land is the carrier of all human activities and the material basis for human survival.In recent years,unreasonable land use has produced a series of environmental problems,threatening the survival and development of human beings.Constructing the ecological security pattern of land use is an important way to realize regional ecological security.It helps to protect the land ecological environment,optimize the allocation of land resources and promote the sustainable use of land.This paper takes the land ecological security of Tianjin is as the research object.With the help of GIS,we take 30m×30m grid as the research unit to evaluate the land ecological security level and spatial distribution in Tianjin.On the result of the land ecological security assessment,we construct the land use ecological security pattern and put forward some suggestions.The main research contents and conclusions are as follows:(1)From the perspective of resilience,this paper uses the matter element analysis methods,constructing the identification model from versatility,suitability,redundancy and stability to evaluate the land ecological security level and spatial distribution in Tianjin.The results showed that:The comprehensive land ecological security in Tianjin belongs to relatively security level.For single indicators,the main restrictive factors of land ecological security in Tianjin are water source influence degree,groundwater resource exploitation degree,landscape fractal dimension index grain production capacity and the degree of aggregation of ecological land.The ecological security of land in Tianjin can be divided into four levels:high security,relatively security,critical security and insecurity.The area of each level is 2028.32km2,3971.32km2,2419.60km2 and 3314.05km2respectively,accounting for1 7.29%,33.85%,20.62%and 28.24%respectively of the total area of the study area.The spatial difference of comprehensive land ecological security in Tianjin is obvious,presenting a spatial distribution of high in the north and low in the south,high in the central and low in surrounding area.The high security areas are mainly distributed in the northern part of Jizhou district and Baodi district;the relatively security areas are widely distributed with farmland and water wetland as the main land use type;the critical security areas are scattered,mainly distributed in the south of Wuqing District and Jinghai District;the insecurity area shows a certain centrality,mainly distributed in the Ring four (Dongli District,Xiqing District,Jinnan District and Beichen District) and Binhai New District.(2)This paper selects the high security and ecological red line areas as the source of land use ecological security pattern.With the minimum cumulative resistance model,we choose land use type,distance from water source,distance from road and distance from active fault zone as resistance factors to constructing the minimum cumulative resistance surface of ecological source expansion.On this basis,we divided Tianjin into three levels of ecological security pattern buffer zones:high,medium and low,identified the ecological corridors and constructed the comprehensive ecological security pattern of land use in Tianjin.The total area of ecological source is 1960.26km2,accounting for 16.70%of the total area of the study area.The main land use types of ecological source are forest land and river reservoirs,which are distributed in discontinuous islands and zones in space.The area of high-level buffer is 1239.49km2,which accounts for 10.56%of the total area of the study area.The area of medium-level buffer is 4461.94km2,which accounts for 38.02%of the total area of the study area.The area of low-level buffer is 4092.73km2,which accounts for 34.87%of the total area of the study area.We identifies 61 ecological corridors,with a total length of 1781.48km.The spatial distribution of ecological corridors is dense in the north and sparse in the south,with irregular curve distribution,forming a circular corridor layout. |
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