Study On The Evolution And Driving Factors Of Ecological Environment In The Taitema Lake Area In Recent 30 Years

The ecological environment evolution in arid regions is one of the key contents of global change research.The application of remote sensing monitoring technology provides the possibility to monitor and analyze the macro-ecological environment in arid regions.The Taitema Lake area in Xinjiang is part of the generalized Lop Nur.The precipitation is scarce,the evaporation is huge,the vegetation is sparse,and the ecological environment is extremely fragile.It is a sensitive area for global climate change response.This article uses this as a research area,refers to relevant literature,downloads and analyzes satellite remote sensing images,and uses methods such as mean method,correlation analysis method,trend analysis method,and regression analysis method.This paper analyzes the spatial and temporal characteristics of vegetation index,regional vegetation type structure and water body area change since the 1980 s,and makes qualitative and quantitative analysis of its influencing factors from two aspects: natural and human.Research indicates:(1)From 1988 to 2017,the linear trend of the annual maximum vegetation index in the Taitema Lake region was 0.009/30 a,indicating that the NDVI has been weakly increasing since the 1980 s and is generally stable.However,the change of vegetation cover has obvious characteristics of stage change.The NDVI fluctuation of vegetation after the 1990 s is greater than that of the 1980 s.After entering the 21 st century,the annual maximum NDVI value increased significantly and maintained a rapid and sustained growth.The vegetation coverage in summer showed an increasing trend,and the area of the improved area increased.The spring and autumn showed a downward trend,and the vegetation degradation status was significant.Based on the spatial characteristics of vegetation cover,the overall vegetation coverage area of the study area is small,mainly distributed in the western part of Lake Taitema and the area with good natural water conditions.The area of vegetation improvement area is slightly larger than that of the degraded area.(2)The vegetation types in the Taitema Lake area are mainly grassland,woodland and cultivated land.The area occupied by grassland has always been in an absolute advantage,followed by forest land,and the overall cultivated land area has shown a downward trend;The overall NDVI of vegetation types showed a slight growth trend,in which the NDVI uptrend trend was the most significant,and the forest land and grassland fluctuated within the time series.The vegetation type structure in the study area is unstable and variability.It constitutes the basic pattern of ecological environment in which the desert and low-coverage vegetation are dominant in the Taitema Lake area,but the ecological environment is generally improving.(3)From 1988 to 2017,the water area and distribution area of the Taitema Lake area changed drastically,and the water area as a whole showed a volatility growth trend,and there were significant phase characteristics.Taking 2000 as the turning point,the water area in the 1990 s was small and the changes were stable.After 2000,the water area showed obvious expansion and migration.From the spatial variation characteristics,the water body distribution extends from the western part of the Kanglake Wetland and the local area of the Taitema Lake to the Bostan area.Around 2010,the waters were mainly distributed on both sides of the Kanglake Lake Group and National Highway 218.In recent years,the Lake District has gradually shrunk and a small amount of water is distributed in the Bostan area.(4)The annual precipitation,annual average temperature and annual relative humidity of the Taitema Lake area are on the rise,while the annual average sunshine hours are decreasing.The seasonal difference is large,the phenomenon of rain and heat is more obvious,and the climate develops toward warm and humid.Through quantitative analysis of meteorological elements,vegetation index,and water area,it is found that the relative humidity of light and air is the main limiting factor of vegetation growth.Among them,the relative humidity of autumn air is more significant,the contribution rate is 17.2%,and the contribution rate of spring sunshine hours is 16.4%.And the response of vegetation to natural elements has the doubleeffect of “real time” and “lag”,and the lag period is a seasonal scale.The change of water area is mainly affected by spring precipitation and annual sunshine hours,and their contribution rates are 29.7% and 16.3%,respectively.Grassland is greatly affected by natural factors such as climate.Forest land and cultivated land are significantly affected by ecological water transfer projects.The significant increase of cultivated land vegetation index is closely related to irrigation and management.In recent years,the influence of human activities has become more and more prominent,and it has played a decisive role in the changes of the ecological environment.After2000,a large-scale ecological water transfer project was carried out in the Tarim River Basin,which is conducive to the improvement and sustainable development of the ecological environment in the study area.In the time series of the study,the evolution of the ecological environment in the Taitema Lake region is mainly due to the combination of natural and human factors.After the 21 st century,the positive effects of human activities played a decisive role.In the future development,we should optimize the allocation of water resources,vigorously implement ecological engineering construction,strengthen ecological supervision,promote local ecological balance,and achieve harmonious coexistence between man and nature.