Remote Sensing Monitoring on Dynamic of Sandy Desertification Degree in Horqin Sandy Land at the Beginning of 21st Century

Land use types were classified and the visual interpretation remarks were established by taking TM images in 2000 and ETM images in 2005 as information source.Then the dynamic of sand desertification degree in Horqin sandy land since 2000 was monitored with the help of images and data processing function of ERDAS.During the remote sensing monitoring period,the slight desertification land has obvious increasing trend,the area had been increased by 635.8 km2.The moderate,severe and serious desertification lands developed in the direction of reducing,their area had been reduced by 195.0 km2,313.8 km2 and 145.6 km2 respectively.For each type of desertification land,the area of slight desertification land increased,that of severe and serious desertification lands reduced;the area of moderate desertification land increased in the type of sand reactivating or moving sand invading,and decreased in the types of bush desertification and farmland desertification.The reversed desertification lands mainly came from the slight and the severe types;the newly increased desertification land mainly happened in the moderate and severe desertification lands.