Temporal And Spatial Pattern Changes And Driving Force Analysis Of Ecological Environment Vulnerability In Panzhihua City

With the rapid development of the economy,the increasingly contradictory between human and natural environment and the improvement of people's awareness of environmental protection,the change of regional ecological environment vulnerability has become one of the core contents of global environmental change research.Panzhihua City is an important ecological barrier in the upper reaches of the Yangtze River,and it is a typical agricultural,forestry and animal husbandry eco-fragile area in China,located in the dry-hot valley of the Jinsha River.Due to the region has large terrain relief,high altitude difference,uneven distribution of hydrothermal conditions,poor soil quality and complex geological structure,the ecological environment is inherently fragile.In addition,mineral resources and water resources such as vanadium and titanium are abundant in the region.At the same time,high-frequency,large-scale urban economic development and construction such as mining,agriculture and animal husbandry have been carried out in recent years,and have intensified many serious ecological problems such as soil erosion and groundwater pollution in the region.Under the dual influence of natural factors and human activities,Panzhihua City has obvious regional ecological degradation,and the relevant departments have also been strengthening the ecological protection of regional forests and waters by implementing ecological protection construction projects such as “Tianbao Project”.Therefore,scientific understanding of the spatial and temporal dynamics and driving mechanism of the ecological environment in Panzhihua City is of great significance to regional ecological environmental protection and planning construction.Although there are already some theoretical and methodological explorations for the ecological environment protection and construction of Panzhihua City,the research on the spatial and temporal pattern changes and driving mechanism of the ecological environment vulnerability of Panzhihua City is still lacking.This paper takes Panzhihua City as the research object,and selects theevaluation factor from the model of “Ecological Sensitivity-Ecological Recovery-Ecological Pressure” to construct an evaluation system suitable for the ecological environment vulnerability of Panzhihua City.Based on multi-source remote sensing data,multi-year meteorological data,basic geographic data,and other statistical data,we use establish a spatial database of ecological environment vulnerability assessment factors for Panzhihua City from 2005 to 2015 by using spatial information technology such as remote sensing interpretation,“multiple regression + residual interpolation”,minimum dichotomous model,soil erosion equation and nuclear density estimation.Using spatial principal component analysis method,CA-Markov model and dynamic degree model explores the differentiation characteristics of spatial and temporal changes of ecological environment vulnerability in Panzhihua City from 2005 to 2015.And using the geo-detectors quantitatively explores the spatial stratification heterogeneity relationship between the ecological environment vulnerability of Panzhihua City and its driving factors to provide a scientific theoretical basis for regional ecological protection and construction.The main research results are as follows:(1)Combining the natural ecological conditions of Panzhihua City with the existing ecological problems,we build an evaluation system with 14 evaluation indicators,which is based on the model of “Ecological Sensitivity-Ecological Recovery-Ecological Pressure”.Sensitive layer selects 7 indicators including topography,soil,vegetation and meteorological factors;The recovery layer selects four indicators: landscape diversity,biological abundance,localization point interference density,and mine site interference density;The pressure level selects three indicators of per capita GDP,population density,and cultivated land ratio.(2)Using the spatial principal component to construct the ecological environment vulnerability assessment model of the third phase of Panzhihua City.Then,through the spatial analysis and statistical analysis of the results of the ecological vulnerability classification of the study area in 2005,2010 and 2015,the spatial differentiation characteristics of the ecological fragile situation in Panzhihua City are as follows: The overall vulnerability of Panzhihua City is gradually increasing in the northwest to the southeast,and the overall ecological quality is medium;The regional differences are obvious.Moderately and above vulnerable areas are located in the central and eastern regions where population is concentrated and economic activities are frequent of the study area.and the micro-degree andbelow vulnerable areas are mainly distributed in most areas with good vegetation coverage in Yanbian County and Miyi County.(3)Using the transfer matrix,multiple dynamic degrees of change,overall state and trend change index to statistically analyze the ecological vulnerability results of the study area from 2005 to 2015,the overall rate of vulnerability change in Panzhihua City from 2005 to 2015 is severely vulnerable > Potentially vulnerable >Moderately vulnerable > Micro-fragile > Mildly vulnerable.The annual average overall dynamic degree is 0.04,and the overall vulnerability trend has a small change range of only 0.12,showing a balanced bidirectional transition state between adjacent vulnerability levels.And the overall ecological vulnerability index has gradually declined from 2.7051 in 2005 to 2.6151 in 2015,indicating that the ecological fragile situation in the study area is developing in a gradual recovery direction.(4)The risk factor detection model of geographic detector is used to quantitatively analyze the spatial stratification heterogeneity between the ecological vulnerability of the study area and all the evaluation indexes.It shows that the influencing factors of vegetation coverage,elevation,annual average temperature,annual precipitation and landscape diversity index are similar to the spatial distribution of ecological fragility in Panzhihua area,and that vegetation coverage,landscape diversity index,elevation,temperature and precipitation factor are the main driving forces for the change of ecological environment vulnerability in Panzhihua City from 2005 to 2015.Then,using the statistical analysis model of interaction detection in geo-detectors quantitatively analyzes the explanatory power between the interaction between all indicators and the ecological vulnerability of the study area.It is found that the interaction between the two factors has a two-factor enhanced relationship to the driving force of ecological vulnerability in the study area,which indicates that the ecological vulnerability of Panzhihua City is formed by the combination of multiple factors.