Spatio-temporal Dynamics Of Vegetation Coverage And Its Relationship With Climate Factors In Lop Nor,china

Xinjiang is located in the Asia-Europe continental interior,belongs to the arid and semi-arid climate zones,is an important barrier to the northwest region ecological environment.The ecological environment in the region is bad,the climate is arid and the vegetation coverage is low.Lop Nor is located in the east of the Tarim Basin,in the Xinjiang Bayingol Mongolian Autonomous Prefecture.Lop Nor is in the west of the Taklamakan desert and the Kurotague desert.The southeast is connected to the Kumutag desert.There is little precipitation in the Lop Nor,and humans only operate in a few oasis areas.In 1972,the first landsat satellite launched in the United States found that our country's Lop Nor had dried up,presenting a "big ear" shape.After the lake dried up,the plant species rapidly declined.This paper takes 1988-2017 as the research period,and takes Lop Nor as the research area.Using data from Ruoqiang meteorological stations and landsat data,Using the average method,regression analysis,trend analysis,correlation analysis and other methods,reveals the spatial and temporal variation of vegetation cover in Lop Nor and its response to climatic factors.The results are as follows:(1)From 1988 to 2017,the linear variation trend of the average NDVI value in the Lop Nor is-0.006/30 a,indicating that the NDVI has declined slightly since the 1980 s.The research area is divided into the Lop Nor basin,the Aztec valley,the Tarim river region,Ruoqiang county and the surrounding area.From 1988 to 2017,the average value of NDVI from big to small is Ruoqiang county and the surrounding area,the Aztec valley,the Tarim river region,Lop Nor basin.The NDVI value of the Lop Nor basin,the Aztec valley and the Tarim river region has been declining for nearly 30 years,and the NDVI value of the Ruoqiang county and the surrounding area has been in a weak upward trend for nearly 30 years.(2)The spatial distribution of NDVI in Lop Nor is: Ruoqiang county,Milan town and Tieganlike town are the most concentrated areas of human activity in the whole research area,the vegetation coverage is better,and NDVI value is the largest.The vegetation coverage of the Aztec valley and the area of the river flowing through is also high in other areas.(3)From 1988 to 2017,the area of vegetation cover decreasing trend is the junction of Taklimakan Desert and the Tarim river region,the former Qarqan River basin,the city center area of Ruoqiang county and the central area of Milan town.the area of vegetation cover increased is the Ruoqiang county,Milan town,Washixia town,Qarqan River basin,Tieganlike town and Tarim river region.The vegetation coverage in the whole study area remained relatively stable.(4)The range of precipitation in the study period between June to September is 3mm-1046 mm.During the 30 years,the precipitation trend line showed a significant upward trend.The range of temperature in the study period between June to September is 24.04 ? to 26.00 ?.The climate in the research area has been warming for nearly 30 years.(5)There is a significant positive correlation between NDVI value and annual precipitation.In the absence of temperature,annual precipitation and annual NDVI partial correlation coefficient are positive correlation,that is,the higher precipitation in the study area is conducive to vegetation growth.The annual mean temperature and NDVI show a significant negative correlation,indicating that the vegetation coverage is decreasing with the increase of temperature.In precipitation variable control case,the annual average temperature and annual average NDVI of partial correlation coefficient is 0.476,0.009,P with P < 0.05 significance test,the temperature and NDVI has a significant negative correlation,consistent with the results of correlation.