Landscape Dynamics of Rocky Desertificated Lands in Karst Mountainous Region of North Guangdong in Recent 30 Years

Based on remote sensing images in Karst area of north Guangdong in 1974,1988 and 2004 and the field investigation,three landscape maps of the Karst mountainous region in north Guangdong were produced.In recent 30 years,the rocky desertification in north Guangdong is experiencing a reverse process.The area of rocky desertification lands in 1974 was 2 042.43 km2,covering 42.47% of the Karst region in study area.In 1988 and 2004,the ratios of rocky desertification lands reduced to 33.95% and 21.14% respectively.Slight rocky desertification land had the fastest decrease speed in the past 30 years among the different degradation degrees of rocky desertification lands,and in 2004 the moderate rocky desertification land appeared to have the largest proportion.The landscape heterogeneity of Karst region depressed continuously,and the landscape connectivity enhanced.The patch density of rocky desertification lands increased but the mean patch area decreased.The area of patches of rocky desertification lands has tended to be even.