Study On Changing Regularity And Influencing Factors Of Ecological Vulnerability In Shandian River Basin

With the development of social economy and global climate change,the ecological environment has been seriously damaged,especially the ecological vulnerability of wetland ecosystem,which is the "lung of the earth",has gradually increased.Its ecological function is aggravating degradation and loss,but previous studies on the essence of ecological vulnerability and the analysis of influencing factors are still not in-depth.This paper takes the Shandian River Basin in Hebei Province as the research object,using GIS,the ecological vulnerability of the Shandian River Basin was evaluated and its influencing factors were analyzed by selecting 11 evaluation index factors of natural,man-made and socio-economic factors,such as average annual precipitation,vegetation coverage,landscape fragmentation,population density,per capita GDP,soil erosion,forest land and grassland degradation,and the like,in order to provide research basis and theoretical basis for wetland protection.The main results are as follows.(1)Influence of Land Use on Eeological Environment in Shandian River BasinThe analysis of landscape patterns and land use changes in the upper reaches of the Shandian River Basin showed that forest land,cultivated land and unused land were the main landscape types in the study area,while grassland and water area were less distributed.The percentage of each type of land area from large to small was unused land(49.87%),cultivated land(28.09%),forest land(16.26%),grassland(5.31%)and water area(0.48%),respectively.The cultivated land area,grassland area,forest land area and water area in land use showed a downward trend from 1995 to 201 5.However,the area of unused land is increasing.From the perspective of land conversion,the conversion area of cultivated land is larger than the replenishment area,and the conversion area of forest land and grassland is also larger than the replenishment area.Land use types are converting with each other,and forest land,grassland and cultivated land are all in a downward trend.The landscape shape index is consistent with the change trend of patch density.With the passage of time,the degree of landscape patch fragmentation decreases first and then increases,and the ecological environment also changes.(2)Change Regularity of Ecological Vulnerability in Shandian River BasinOn the whole,the ecological vulnerability gradually deepened from 1995 to 2015.The generally fragile areas began to change to moderately fragile areas,and the moderately fragile research areas began to change to highly fragile areas.The research areas as a whole were in a state of moderately fragile.In terms of spatial distribution,The change of ecological vulnerability in the Shandian River Basin gradually decreased from the northeast to the southwest,Ecological vulnerability is generally higher in the north than in the south,The year 1995 was dominated by extreme vulnerability,However,by 2015,the overall vulnerability is mainly moderate,and different types of vulnerability are changing from extreme vulnerability to moderate vulnerability in the central and northern regions,from low vulnerability to general vulnerability in the alpine and hilly regions in the southeast,and from general vulnerability to moderate or high vulnerability in the vicinity of the Shandian River in the central region.From the analysis of time changes,the ecological vulnerability of Shandian River Basin fluctuated from 1995 to 2015.In 1995,the ecological vulnerability value in the southern region was 0.7314,that in the southeast region was 0.6749,that in the central and northern regions was 0.9201,and that in the northeast region was 0.7528.By 2015,it will be 0.6853,0.7468,0.6812 and 0.6343 respectively,which shows that the ecological vulnerability of Shandian River Basin has been changing continuously in the past 20 years.(3)Study on Influencing Factors of Ecological Vulnerability in Shandian River BasinPrincipal component analysis of 11 variables related to ecological vulnerability in the study area shows that,The most important variables contributing to the ecological vulnerability of the Shandian River Basin are annual average temperature and annual precipitation,followed by slope,soil erosion,forest land and grassland degradation,and the third is per capita GDP and soil erosion.The combined effect of these factors leads to the formation and development of ecological vulnerability in the Shandian River Basin.Further analysis shows that the ecological vulnerability of the Shandian River Basin is the result of the joint action of human activities and natural factors.The influencing factors of the ecological vulnerability of the Shandian River Basin are mainly manifested in three aspects:natural factors,social conditions and soil erosion.The above research results show that,the change of land use pattern will affect the change of ecological environment.This will lead to changes in ecological vulnerability.The change of ecological vulnerability in the study area is obvious,and the ecological vulnerability is in a rising state.The ecological vulnerability in the study area is mainly caused by the combined action of natural factors and human factors.The main influencing factors of ecological vulnerability in the study area are annual average temperature,annual precipitation,slope,soil erosion,forest land and grassland degradation and per capita GDP...