The Influence Of Climate Change Over The Temporal And Spatial Variation Of Desertification Of Four Main Dune Fields Over The Past 30 Years In Northern China

This article applied 3S technology to the study of desertification on the basic of domestic and foreign researches recently,And use the quantitative index:vegetation index to study the temporal and spatial variation of desert boundary,areas,vegetation coverage and desertification of four main dune fields in china over the past 30 years and the influence of short time scale climate change over desertification,The following conclusions can be draw:1)The land of desertification in four main dune fields show slow expansion over the past 30 years,the velocity of desertification decrease gradually from north to the south,east to the west and the period of rapid desertification ahead of time gradually.Hulunbuir dune field expanded mainly on 200-2012,at the rate of 52 km2/a,the expansion ratio is 15%;Horqin dune field expanded at the rate of 87 km2/a,the expansion ratio is 4.5%;Hunshan Dake dune field expanded mainly on 1990s,at the rate of 29 km2/a,the expansion ratio is 1.3%;Mu Us dune field expanded slowly after 1990s,at the rate of 7 km2/a,the expansion ratio is 0.5%.2)Four main dune fields show different features in respond to the climate change.The main factor that drive desertification is the effect of climate is fade while the effect of human activity is strong.The climate change of Mu Us dune field in favor of the improvement of desertification;The variation of changeable precipitation of Horqin and Hunshan Dake dune field is the main climate factor that drive desertification but not as strong as human activity;The desertification of Hulunbuir dune field main due to the human activity.3)Over the past 30 years,the vegetation coverage of four main dune fields show step-improvement,the improvement increased from west to the east,north to the south.The vegetation coverage fluctuated significantly while increased significantly in 6 years from 1982 to 1987;the vegetation coverage fluctuated in small range and relatively stable in 15 years from 1987 to 2001;the vegetation coverage increased significantly in 5 years from 2005 to 2006.Besides,the improvement of desertification increased from north to the south,the improvement rang from the best Horqin,than Mu Us,than Hunshan Dake to the worst Hulunbuir dune field.4)The fluctuation of local and short time scale change of temperature,precipitation,wind speed and so on have great influence over vegetation coverage and desertification.The vegetation coverage have close relationship with precipitation,the increased precipitation before growing season as well as the reduction of wind speed helped the prosperity of plant in four main dune fields.The improvement of desertification and vegetation coverage of four main dune fields show decrease dependence on precipitation from south to the north,west to the east,the reduction of wind at growing season also have great influence over vegetation coverage.The great improvement of desertification and vegetation coverage in Horqin have close relationship with the increase of precipitation of growing season,rapid reduction of wind speed and the increase of temperature;The improvement of desertification and vegetation coverage in Hunshan Dake have close relationship with stable increase of precipitation from March to July;the increase of vegetation coverage in Hulunbuir have close relationship with the increase of precipitation before growing season;The improvement of desertification in Mu Us have close relationship with the reduction of wind speed and the increase of both precipitation an temperature.