Dynamic Assessment Of Environmental Vulnerability In Karst Mountain City Based On SRP Model-Taking Guiyang City As An Example

With the rapid development of urbanization and social economy,human demand for resources continues to increase.Unreasonable use of resources has led to a continuous decrease in the stability and self-recovery capacity of the ecosystem,causing a series of ecological and environmental problems.The contradiction between the two has become increasingly prominent,posing a serious threat to social development and ecological security.Under such a general background,scientifically evaluating the dynamic characteristics of the fragility of the regional ecological environment and identifying its main driving factors will not only help promote the coordinated development of economy and environment,but also have important guiding significance for the construction of ecological civilization.As a typical karst mountain city,Guiyang has a poor natural ecological environment.With large-scale development,it is not clear how Guiyang’s ecological vulnerability and driving mechanism have changed under the new situation.With these questions in mind,this paper uses topography,land use,landscape pattern status,meteorological factors,and socio-economic data as the basis to select evaluation indicators from three aspects of “ecological sensitivity-ecological resilience-ecological stress” to construct Guiyang City Ecological vulnerability index evaluation system,and the spatial principal component analysis method is used to quantitatively analyze the spatial differentiation characteristics and temporal changes of the ecological vulnerability of Guiyang in 2000,2010 and 2017.The main conclusions are as follows:(1)On the whole,the ecological fragility of Guiyang City is mainly moderately and slightly fragile,and the overall ecological environment quality is medium.The intensity of ecological fragility gradually weakened outwards from the central urban area,showing a distribution characteristic of “high in the south and low in the north”.The ecological environment of cities and industrial clusters in the southern region was destroyed and the ecological fragility was high;the vegetation coverage rate in the northern region was relatively high,and the ecological environment was high.The environment is relatively optimistic.As the years increase,the severe and extreme vulnerabilities gradually expand outward from the center of the old city,the moderate vulnerabilities gradually expand northward,and the mild and slight vulnerabilities gradually shrink.(2)Among the 10 counties,Yunyan District and Nanming District have the highest ecological fragility,and are extremely vulnerable as a whole,while Kaiyang County has a better ecological environment and is a slightly fragile area as a whole.In the past 17 years,the proportion of ecological fragility and the average EVI of various counties have increased to varying degrees.Among them,the ecological fragility of Guanshanhu District,Baiyun District,and Qingzhen City has increased the fastest.(3)From the perspective of the ecological fragility of different land use types,the ecological fragility of construction land is the highest,and the ecological fragility of woodland is the lowest.With the passage of time,the ecological fragility of each category is increasing.From the perspective of the ecological fragility of cultivated land with different slopes,the ecological fragile area of cultivated land is mainly concentrated in the slope range of 6° to 25°.Cultivated land with a slope of less than 6° is severely affected by human disturbance,and the area of severe and extremely vulnerable areas accounts for a relatively large area,The patterns of land use need to urgent transform.(4)From the perspective of time changes,from 2000 to 2017,the comprehensive index of ecological vulnerability of Guiyang City showed an increasing trend;different levels of vulnerabilities generally showed a phenomenon of “low level of vulnerability to high level of vulnerability”;from different levels of vulnerability In terms of the rate of change,the areas of extreme,severe,and moderately vulnerable levels are increasing at an average annual rate of change of 0.29%,0.03%,and 0.06%,and the areas of mild and mildly vulnerable levels are increasing at an average annual rate of 0.21% and 0.07%.The rate of ecological vulnerability is decreasing;the growth rate of ecological fragility during 2010-2017 is stronger than that during 2000-2010.It shows that the ecological fragility of Guiyang City is continuously deteriorating,and with the rapid development of social economy,the growth rate of ecological fragility is significantly increasing.(5)From the perspective of spatial changes,the areas with a sharp increase in ecological fragility are mainly distributed in Guanshanhu District,Baiyun District and Qingzhen City,which are highly similar to the regions where the urban expansion of Guiyang City has realized the“Northern Extension and Western Connection” strategy;slight decline and stability The unchanging areas are mainly concentrated in the areas with higher altitude and higher vegetation coverage in Guiyang,indicating that ecological projects such as returning farmland to forests and stony desertification control can promote the stability and restoration of City’s ecosystem to a certain extent.(6)From the perspective of driving factors,the degree of land use,NDVI and soil erosion rate are the main driving factors that cause City’s ecological vulnerability.At the same time,per capita GDP,population density,landscape diversity index,slope and topographic undulation are the main driving factors for Guiyang City’s ecological vulnerability.Ecological vulnerability has varying degrees of impact.On the whole,the influence of regional man-made disturbance driving factors on ecological vulnerability is more dominant than natural driving factors.As time goes by,the intensity of man-made disturbance is gradually increasing,and City’s ecological environment is facing serious threats.