| Changes in land use/cover patterns can cause changes in the spatial distribution patterns and types of terrestrial ecosystems,thus affecting the types and intensity of services of terrestrial ecosystems.Vegetation is an important part of terrestrial ecosystem,and the change of vegetation coverage is affected by human activities and changes of natural geographical environment.Vegetation coverage is an important parameter of vegetation characteristics,and using normalized vegetation index is to characterize vegetation monitoring and analyze the dynamic changes of vegetation in ecologically sensitive areas and its relationship with driving factors,which is of great significance to the construction of regional ecological civilization and sustainable development.The study takes Ordos City of Inner Mongolia,an ecologically fragile area as the research object,divides 7 banners and 2 districts into 8research units,and uses 3S technology to interpret remote sensing image data and NDVI data in 2000,2005,2010 and 2015.Analyze the change trend of land use/cover and vegetation coverage,and the influence of natural factors such as annual rainfall,average annual temperature,soiltype and vegetation type,and human factors such as land use / cover type,total population and GDP per capita on vegetation coverage.The results show:(1)In Ordos,the grassland has the largest distribution area and is mainly dominated by warm grassland and sparse grassland;followed by deserts and bare soil.The forest land is mainly composed of deciduous broad-leaved forest,deciduous broad-leaved shrub and sparse shrub;the cultivated land is mainly dry land and the proportion of wetland and artificial surface is small.(2)The area of woodland,cultivated land and artificial surface increased in Ordos from 2000 to 2015,the area of grassland,bare soil and desert decreased,and the area of wetland changed little.The increase of forest land in Zhungeer Banner,Dongsheng District,Kangbashi District,Etuoke Banner and other regions is more obvious.The increase of cultivated land is mainly dry land,and the dry land in Dongsheng District and Kangbashi District is reduced,which is mainly converted into construction land,the dry land area of the other banners and counties has increased,and the grassland has been formed by wasteland.The increase in the area of construction land and mining yards in various counties has led to the increase of artificial surfaces.Among them,Zhungeer Banner,Dongsheng District,Kangbashi District,Yijinhuoluo Banner haveincreased significantly.The conversion of bare soil and desert into grassland type is the main reason for its area reduction.(3)In Ordos,the vegetation coverage shows an optimization trend of increasing vegetation coverage with high coverage and decreasing vegetation coverage with low coverage.The vegetation coverage of Zhungeer Banner and Yijinhuoluo Banner improved the most,followed by Etuoke Banner,Dongsheng District,Kangbashi District,Dalate Banner and Wushen Banner,the least improvement was achieved in Hangjin Banner and Etuoke Banner.(4)The NDVI value of vegetation in Ordos showed an improvement trend.The vegetation NDVI value in Zhungeer Banner and Yijinhuoluo Banner improved significantly,followed by Wushen Banner and Dalate Banner,with the smallest improvement area in Etuoke Banner,Dongsheng District and Kangbashi District.In terms of the influencing factors of vegetation NDVI value change,the influence of natural factors is greater than that of human factors in 2000 and 2005,while the influence of human factors is greater than natural factors in 2010 and2015. |
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