Study On The Evolution And Driving Mechanism Of Ecoenvironmental Quality In Pisha Sandstone Area

As an important ecological security barrier area,the Yellow River Basin plays a very important role in China’s social and economic development and national ecological security.Ecological protection and high-quality development in the Yellow River Basin has become a major national strategy.As a concentrated source of sediment in the Yellow River Basin,the Pisha Sandstone area suffers from serious soil erosion and extremely fragile ecological environment.At present,this area still faces many ecological environmental problems and ecological restoration and management bottlenecks.Therefore,it is particularly important to timely and accurately grasp the evolution characteristics of spatial and temporal pattern of ecological environment quality in the Pisha Sandstone area and reveal the main controlling factors affecting the evolution of ecological environment quality.In this paper,Landsat remote sensing images from 2001,2006,2011,2016 and 2021 were selected to extract four ecological indicators,namely greenness,humidity,dryness and heat.Remote sensing ecological index RSEI and center of gravity migration model were used to analyze the spatio-temporal pattern evolution characteristics of ecological environmental quality in Pisha sandstone area.12 factors were screened from both natural factors and human factors.Based on the geographical detector,the relationship between different factors and the change of ecological environment quality was revealed and the driving mechanism was explored.(1)Among the four components of the remote sensing ecological index,the greenness and humidity showed a fluctuation and rising trend,and the growth rates were 2.33%/a and 1.73%/a,respectively.The variation of dryness and heat was not significant during the study period.According to principal component analysis,greenness and humidity have positive effects on RSEI value,while dryness and heat have negative effects on RSEI value.(2)The mean RSEI values of remote sensing ecological index in different periods in the Pisha sandstone area are 0.39,0.49,0.45,0.61,and 0.57,respectively,showing a fluctuating trend of "up-down-up-down".From 2001 to 2011,the ecological environment quality in the study area changed from poor to good.From 2011 to 2021,the ecological environment quality of the study area was mainly medium.In general,during the study period,the area of ecological quality improvement accounted for 62.34% of the total area,and the area of ecological degradation accounted for 10.16% of the total area,indicating that the ecological environment quality of the Pisha sandstone area was continuously improved during the study period.(3)The ecological environmental quality of Pisha sandstone has obvious spatial differentiation.The ecological environmental quality of the sore-covered area is better than that of the sand-covered area,and the ecological environmental quality of the sand-covered area is better than that of the bare area.The ecological environment quality of the whole region showed a distribution trend of "high in the east and low in the west,high in the south and low in the north",and this distribution trend became more obvious with the passage of time.Through the analysis of gravity transfer model,the center of gravity of "extremely poor" moves to the northwest of the study area,the center of gravity of "poor" moves to the north,the center of gravity of "medium" and "good" is distributed in the middle of the study area,and the center of gravity of "excellent" is distributed in the southeast of the study area.(4)The order of driving factors affecting ecological environment quality in the arsenic sandstone area is greenness > humidity > heat > dryness >annual rainfall > annual temperature > elevation > land use type > soil erodibility = population density > slope.The four component indexes of RSEI model have the highest correlation with ecological environment quality,and their contribution rates are all above 20%,among which the average contribution rate of greenness index is above 60%,indicating that increasing vegetation coverage in the region is an important way to improve the ecological environment quality of the Pisha sandstone area.The results of risk detector showed that greenness,humidity,annual rainfall and annual temperature were positively correlated with ecological environment quality.Dryness and elevation were negatively correlated.The trend of heat,slope and ecological environment quality increases first and then decreases.After reaching a critical value,the ecological environment quality will become worse.