| Ecological environment quality is the embodiment of the comprehensive characteristics of the internal factors and the external environment of the ecological system and the basis for quantitative evaluation of the regional ecological environment.In recent years,with the advancement of China’s ecological civilization construction,the environment in ecologically fragile areas has been highly valued,and the comprehensive evaluation of ecological environment quality has become a research hotspot.Known as the "water tower of north China",Shanxi province is also the water conservation land and the ecological barrier of sandstorm source in Beijing-Tianjin-Hebei region.However,its ecological environment is fragile and greatly affected by the changes of natural factors and human social and economic activities.Therefore,how to construct ecological environment quality index and explore its spatio-temporal change law and driving mechanism are of great importance for promoting the construction of ecological civilization in Shanxi.In this paper,fractional vegetation coverage(FVC),leaf area index(LAI),gross primary productivity of vegetation(GPP),land surface temperature(LST),and wetness(WET)were retrieved from Moderate Resolution Imaging Spectroradiometer(MODIS)satellite remote sensing products in 2001,2005,2010,2015 and 2020.Principal component analysis(PCA)has been used to establish the MODIS data-based ecological index(MODEI)in the study area and to analyze the spatial-temporal pattern of the changes of the ecological environment quality of Shanxi Province in the past 20 years.The driving mechanism of ecological environment quality change in Shanxi province by using the geographical detector and correlation analysis.The results show that:(1)The overall ecological environment quality in Shanxi Province is moderate,but the regional differences are still significant.During the 20 years from 2001 to 2020,the areas with poor and poorer ecological environment quality were significantly reduced,and the areas with medium,good and excellent grades were significantly increased.The ecological environment quality in the "medium","good" and "excellent" areas of the province are mainly concentrated in the middle and high mountain areas.The regions with larger space for improvement of ecological environment quality grade are mainly distributed in the northern sandstorm area,the central basin and the western loess hilly region.Ecological environment quality in Shanxi Province has a positive spatial correlation,but spatial aggregation is gradually weakened and the random distribution trend was slightly enhanced.The pattern of local autocorrelation was similar in each target year.The high-high concentration area was mainly distributed in the southeast of Shanxi Province,and the low-low concentration area was mainly distributed in the northwest of Shanxi Province.(2)The changes of ecological environment quality in Shanxi Province are characterized by "overall continuous improvement,and partial slight degradation".From2001 to 2020,the area ratio of ecological environment quality improvement was 56.92%,and the improvement areas were mainly in the northern sandstorm area and the western loess hilly region.The area that remains unchanged accounts for 38.45%,and it is mainly distributed in middle and high mountain areas such as Taihang Mountain,Zhongtiao Mountain,Taiyue Mountain and Lvliang Mountain.The proportion of degraded area is only 4.63%,and the spatial distribution of degraded areas is different in different stages.Within the adjacent time interval with five years as the interval,the conversion of different levels mainly occurred in the adjacent levels.The degradation area of ecological environment quality decreased year by year,and the improvement area increased year by year,and the improvement area was always larger than the degradation area,which could be divided into four stages: rapid improvement(2001-2005)-slow improvement(2005-2010)-slow improvement(2010-2015)-rapid improvement(2015-2020).(3)From the point of each municipal administrative region,the average value of MODEI in Datong,Shuozhou,Xinzhou,Lvliang,Linfen and Yuncheng has been improved,and the improvement of ecological environment quality is the most prominent,and the improvement of the ecological environment quality is the most prominent,with the improvement area remaining above 55%.The average value of MODEI in Yangquan,Jinzhong,Jincheng and Changzhi has maintained a relatively high level.From 2001 to2020,various ecosystems in Shanxi Province have been upgraded with MODEI,and the ecological environment quality has been improved.However,there are great differences in the ecological environment quality of different types of ecosystems,and the ecological environment quality of forest and shrub ecosystems is superior to those ecosystems that are greatly affected by human activities,such as settlement ecosystems and mining area ecosystems.(4)The results of geographical probe showed that topography,land use and soil were important factors that affected the changes of ecological environment quality in Shanxi Province,and the influence of precipitation from 2010 to 2020 was greatly enhanced.The influence of nighttime-light increases to a small extent in the middle and late stage,indicating that human activities and social economic level have gradually become important factors affecting the ecological environment quality in Shanxi Province.The interaction between factors in each period had a greater impact on the spatial differentiation of ecological environment quality.Correlation analysis showed that elevation and slope had a positive correlation with ecological environment quality index as a whole,and ecological environment quality index increased with the increase of elevation and slope.The ecological environment quality of shady slope was better than that of hillside facing the sun,and that of mountainous region was better than that of plain and basin.In terms of climate,the response of ecological environment quality to precipitation is greater than that of temperature.Eco-environmental quality has a negative correlation with population density and a negative correlation with nighttime-light in the southeast of Shanxi Province.The ecological environment quality of Shanxi Province has been continuously improved in the past 20 years,but there is still much room for improvement in some areas.From the point of view of protection and restoration of ecological system,this study proposed that each region should carry out the protection and restoration of ecological space division according to the local actual situation.At the same time,it is necessary to control the disturbance of unreasonable human activities on the ecological environment and avoid the excessive development of land resources while not destroying its natural conditions. |
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