Spatial-temporal Evolution Of Landscape Ecological Security In The Affected Region Of The Lower Yellow River And Pattern Optimization

Due to the acceleration of urbanization,social problems such as man-land contradiction,natural environment deterioration,environmental pollution,and so on appear one after another,and the research on land use change and regional environmental security arises at the historic moment.In recent years,the construction of regional ecological security pattern has become a research hotspot due to the deepening discussion on ecological construction security management.Based on this,this study took the affected areas of the Lower Yellow River as the study area,and applied landscape pattern index and GIS spatial analysis technology to study the spatial-temporal evolution and spatial distribution characteristics of land use landscape in the affected areas of the Lower Yellow River from 2000 to 2018.By choosing landscape pattern index,landscape ecological security evaluation model is set up,in the quantitative analysis of the regional landscape ecological security situation and the basis of landscape ecological security level,and the introduction of statistical analysis method,and through the analysis of the spatial interpolation method evaluating the affected areas of the Lower Yellow River in recent 20 years and space distribution characteristics of landscape ecological security.On the basis of quantitative analysis of regional landscape ecological security and classification of landscape ecological security,geostatistical analysis method was introduced,and spatial interpolation method was used to analyze and evaluate the spatial and temporal distribution characteristics of landscape ecological security in the affected areas of the Lower Yellow River in recent 20 years.In addition,spatial autocorrelation analysis was used to explore the spatial heterogeneity of landscape ecological security in the lower Yellow River.Based on the minimum cumulative resistance(minimum cumulative resistance,MCR)model,ecological sources were extracted and resistance factors were selected to generate comprehensive resistance surface,identify ecological corridors and nodes,and construct ecological security pattern for regional ecological environment problems.The study conclusions are as follows:(1)During the study period,the landscape distribution of cultivated land is relatively concentrated,while the landscape of built-up land is generally dispersed and partially concentrated.Different landscape types have great differences in spatial and temporal distribution.In terms of landscape area,the order of landscape area is cultivated land > builtup land > grassland > forest land > water area > unused land.In terms of spatial distribution,the changes of landscape types are mainly concentrated in the northeast of the region,which is mainly manifested by the transformation of other landscape types to built-up land and water area.Although other landscape areas have changed,the overall change rate is small.The diversity index increased,the spatial heterogeneity of landscape was enhanced,and the landscape fragmentation was serious.(2)From 2000 to 2018,the spatial distribution pattern of landscape ecological security in the affected area of the Lower Yellow River showed obvious regularity and heterogeneity,and the proportion of the area of each landscape ecological security grade was “small at both ends and prominent in the middle”.The similarity was mainly reflected in that the landscape types with high ecological security were mainly forest land,grassland and water area,and the sensitive level was widely distributed in the region,while the risk level was less distributed in the northeast of the region.The difference shows that the level of landscape ecological security in northeast part of the region presents an overall trend of rising.The changes of sensitivity level and critical safety level are obvious in most cities in central China.(3)During the study period,there was a significant positive spatial correlation between landscape ecological security and community distribution,and the spatial change of agglomeration type was obvious.It is mainly concentrated in high-value(H-H)and low-value(L-L),and the low-value and high-value heterogeneous areas show sporadic distribution characteristics.The high-value agglomeration area itself has a high level of landscape ecological security and the surrounding area has a relatively high level of landscape ecological security,showing a high-level agglomeration state of “high in the middle and high in the surrounding area”,which is mainly concentrated in the areas with high ecological security(relative security level and security level)as the core.Low-value agglomeration areas show a low-level agglomeration state of “low in the middle and low in the periphery”,and are in a state of low ecological security(risk level and sensitive level).They are mainly distributed in Dongying city and Binzhou City of Shandong Province.Influenced by human activities,the landscape types are mainly built-up land.The high-value and low-value heterogenous regions show the characteristics of “scattered distribution and not obvious overall change” in space.The most obvious change occurred in the northeastern part of the study area,where the scope of L-L cluster was shrinking and gradually changed from LL cluster to HH cluster.(4)A total of 98 ecological corridors were generated through Linkage mapper,with a total length of 7329.25 km and 60 ecological nodes.Based on MCR model,the study areas were divided into core protection zones,general protection zones,ecological buffer zones,production and living zones and key development zones.Among them,core protected areas are surrounded by general protected areas,which mainly include woodland and water areas with relatively high ecological service function and sensitive ecological environment.The land type of general protected areas is mainly woodland and grassland,and the water area distribution is smaller than that of core protected areas.The ecological buffer zone belongs to the middle level ecological security zone,which is the transition zone and important barrier between ecological protection and human activities.The production and living area belongs to the low-level security pattern area,which is mainly located in the middle of the affected areas of the lower Yellow River and becomes an important area for agricultural production and activities.The key development zones are far away from the ecological source areas,and the main landscape types are cultivated land and urban built-up land.