Study on grassland degradation in Guinan County based on spatial information techniques

On the basis of landscape ecology theory,remote sensing images of four periods(1976,1996,2001,and 2006) were used to analyze the changeable characteristics of grasslands in Guinan County by combining RS technique and GIS technique.This study indicated that the 59 046.13 ha grassland lost in the past 30 years,taking up 12.62% of the total grassland area in Guinan County.Accompanying by loss of grassland,the quality of grassland reduced greatly.The high cover grassland area was greatly decreased by 106076.80ha,accounting for 28.87% of the total high coverage grassland area.The fragmentation of grassland was greatly obvious in the past three decades in Guinan.The fractal dimension values of grassland in 1976,1996,2001 and 2006 were 1.519 3,1.501 1,1.496 7,1.675 4,respectively,indicating that grassland landscape had been greatly disturbed by human activities.Changes of the high cover grassland from 1976 to 1996 had a strong effect on grassland degradation and the grassland area nearly kept stable during 1996-2006.