Land Use Change And Landscape Ecological Risk Assessment Of Ecological Function Zone In The Upper Yellow River

The health and stability of the ecosystem is the basic guarantee for the governance of the ecological environment,and maintaining the continuous advancement of the regional society and economy.With the rapid improvement of China’s social economy the grabbing and plundering of natural resources,and the increasing disturbance and destruction of the ecological environment,ecological issues have become more and more important everyone.The upper of the Yellow River are regarded as"Chinese water towers",the research on the ecological risks of its land use landscape is very important to reduce the contradiction between man and land,and to encourage ecological environmental protection and harmonious development of society.Due to the high fragility of the ecological environment within the Yellow River Basin and the destruction of certain behaviors of people in the Yellow River Basin,the waste of land resources in the basin,the reduction of biological species,the weakening of the internal self-repair and renewal capabilities of the ecosystem,and soil erosion and other issues often occur.Although great success has been achieved in ecological environment management and ecological engineering construction,the responsibility for ecological protection is still significant and it still takes a long time.Wherefore,in order to explore the risks caused by changes in the landscape pattern of land use to the ecological function zone in the Upper Yellow River,the article uses the four phases of land use data of the study area in 1990,2000,2010 and 2018,With the help of dynamic analysis,land use transfer matrix and landscape pattern index,the distribution trend of land use landscape pattern in the ecological function zone in the Upper Yellow River was quantitatively analyzed;and through the construction of the landscape ecological risk assessment model framework,the spatio-temporal characteristics of the landscape ecological risk in the functional area are explored;finally,through the spatial autocorrelation analysis,the spatial agglomeration characteristics of the landscape ecological risk are revealed.The main findings are as follows:(1)Since 1990,as the intensity of land resource development has increased,the six types of land use have changed to varying degrees.Among them,construction land and grassland are the land types with the largest increase and the largest decrease,with an increase of 148.84 km~2 respectively,a decrease of 130.13 km~2.In addition,grassland and woodland account for a relatively high proportion,and the sum of the proportions of the two is always above 80%,and the distribution occupies a greater advantage.(2)There are differences in the rate of change of land use types in different periods in the ecological function zone in the Upper Yellow River.Sorting the dynamic index of all land types can be obtained:construction land>cultivated land=water area>forest land=grassland>unused land.Among all the land types,only the dynamic degree of construction land has always been a positive growth trend during the study period.(3)Through the analysis of the land use transfer matrix,it can be known that in the29 years of the ecological function zone in the Upper Yellow River,the total area of land use change in the study area is 5774.01 km~2,with a change rate of 16.45%;in different land transfer types Among them,the transfer between arable land,grassland and woodland is dominant.The transferred area is 5,023.37 km~2,accounting for 87.16%of the changed area.(4)From the analysis of the landscape level,it can be seen that the shape of the landscape patches in the ecological function zone in the Upper Yellow River is gradually becoming more complex,the degree of dispersion between patches in the landscape becomes larger,and the connectivity of the landscape becomes weaker.Although the different patch types in the landscape show a constant distribution state that tends to be uniform,there are still dominant patch types in the landscape.From the analysis of the patch type,it can be seen that the patch shape of each patch type is close to irregularity,and the fragmentation degree of the rest of the patch types has increased,and in each patch type,the grassland occupy an absolute advantage.In addition,the agglomeration degree of each patch is arranged from large to small as follows:grassland>unused land>forest land>cultivated land>water area>construction land.Except for construction land,the degree of agglomeration of the rest of the land types is in a downward trend,which can indicate that the dispersion of the landscape of the ecological function zone in the Upper Yellow River has increased during the study period.(5)During the study period,the lower and low ecological risk areas always more than 74%of the total area of the functional area,the overall performance of the ecological risk level was low,showing the distribution traits of"high at the north and south ends,low at the middle",and high ecological risk areas are mainly in densely populated areas,alpine snow-covered mountainous areas and swamps and other areas with high landscape disturbance and loss.In addition,the ecological risk value of the study area showed a fluctuating and decreaseing.The average risk values of the four phases were 0.2122,0.2126,0.2115 and 0.2123 respectively,and the overall ecological security situation has improved.However,the quality of the ecological environment in some areas has declined,the area of high ecological risk areas in the whole district has increased by 384.01 km~2,and the internal stability of the ecosystem has weakened.(6)The global Moran’s I index of the landscape ecological risk values of the four time nodes in the study area are all positive,and they are all higher than 0.51,indicating that the ecological risk values of the area are significantly positively correlated in the spatial distribution,indicating the risk The value exhibits the characteristic of clustering in space.The hot spots are mainly concentrated in the high-risk agglomeration areas of Linxia City,Linxia County and Maqu County.Due to human activities in Linxia City and Linxia County,the ecological environment is greatly disturbed,and the ecological environment is more severely damaged;while Maqu County is due to plateau and mountainous areas.The natural background is in poor condition,and it is difficult for the ecosystem to maintain an orderly operation.The distribution of sub-hot spots is increasing,and most of them are located close to the hot spots,mainly in Maqu County and Linxia County.The temperature spot area in the study area has the widest distribution range and is continuously distributed.The distribution area of the secondary cold spot area and the cold spot area is relatively small and scattered,mainly in Zhuoni County and Lintan County.