Study On The Spatiotemporal Changes Of Ecological Environment And Land Use In The Central Area Of Urumqi

The earth space environment is the living space of human beings for a long time,and its terrestrial ecological environment is closely related to human survival.In recent years,human’s wanton use of natural resources has caused unprecedented damage to the ecological environment.How to accurately obtain the spatiotemporal changes of ecological environment and its influencing factors is the prerequisite for the harmonious development of social economy and ecological environment.Secondly,as the largest and sparsely populated province in China,Xinjiang has a relatively fragile ecological environment.Due to the vigorous economic development and excessive exploitation and utilization of natural resources,the ecological environment in this region has been damaged to varying degrees.In recent years,the state has given priority to the protection of Xinjiang ecological area and taken a series of timely measures to curb its deterioration.Therefore,this paper selects Xinjiang as the background and takes Urumqi central city area as the research area to conduct ecological environmental quality assessment,in order to provide scientific basis for decision makers.In this study takes Xinjiang as the background and Urumqi downtown area as the research target area.Data and years are selected for different scales.For Xinjiang as a whole,product data of 2000,2005,2010 and 2018 are adopted in this paper.Four Landsat images in 1990,2000,2010 and 2020 were selected for the downtown area of Urumqi.Selected the green degree index,humidity index,dryness index and heat index based on principal component analysis(PCA)to construct the ecological environment quality assessment index(RSEI),combined with the data of land use,that xinjiang urumqi city center and the city’s ecological environment quality and the utilization of land,revealing its dynamic development trend,the conclusions are as follows:(1)The contribution rate of the first principal component variable is different in different years.In 2000,the contribution rate of the first principal component(NDVI)was 43.788%.In 2005,the contribution rate of the first principal component(NDVI)was 43.227%.In 2010,the contribution rate of the first principal component(NDVI)was 43.46%.In 2018,the contribution rate of the first principal component(ET)was42.624%.Longitudinal comparison of the first three principal components in different years showed that the first principal component was mainly NDVI and ET,the second principal component was mainly SMC and LST,and the third principal component was mainly LST and SMC.It shows that the contribution rate of different parameters to the principal component fluctuates with time,but the constituent parameters of the principal component basically do not change too much.(2)The overall ecological environment quality in Xinjiang is good,but some areas with low RSEI value include a few areas in Altay region,southern Ruoqiang County in Bazhou region,and Tacheng in Tianshan mountains,etc.The low RSEI value area is most concentrated in Ruoqiang County in Bazhou region,and its relative area is also the largest.From the perspective of the overall changes of various levels in Xinjiang,the ecological environment shows a trend of getting better while being stable.From the analysis of land use data,it can be seen that human activities are increasing year by year,which is mainly inferred from the linear increase of cultivated land and urban residential area,and the downward trend of unused land area.On the whole,the ecological environment quality in Xinjiang is mainly affected by climate change.(3)WET and NDVI in Urumqi’s central urban area have a positive impact on the ecological environment quality,while LST and NDBSI have a negative impact on the ecological environment quality.WET has the largest positive contribution rate on the ecological environment quality,while NDBSI has the largest negative contribution rate on the ecological environment quality.Through the analysis of the average value of RSEI,it is concluded that the ecological environment quality in the central area of Urumqi has experienced a changing process of slightly up-up-slightly down in the past30 years,but on the whole,it shows an obvious upward trend.(4)In downtown urumqi urban ecological environmental quality in the proportion of "bad" and "poor",from the overall trend,"general","good" and "optimal" level is to increase the proportion of area,"poor" grade change is relatively stable,the area of the "poor" grade proportion reduced the most significant,visible in downtown urumqi urban ecological environment is bad,but the overall trend is positive.Based on the analysis of the RSEI grade change,it is concluded that the area proportion of the ecological environment quality in the central area of Urumqi increases by one grade.As a whole,the ecological environment of Urumqi is developing in a better direction,but the development process is slow.(5)According to the entropy weight method,construction land has the largest impact on the ecological environment in the central urban area of Urumqi,with a weight of 0.24;The second is water area,with a weight of 0.19.The weights of grassland,unused land and forest land were 0.15.The weight of cultivated land is the least,only0.12.Because the influence weight of forest land and cultivated land is small,the influence of land use on the overall ecological environment quality in the study area is relatively small.The expansion of construction land will erode the area of ecological land,such as woodland,grassland and unused land,and bring about heat island effect,which has a great impact on ecological environment quality.