Changes of forest landscape and its driving mechanism during the last fifty years in the eastern mountain area of Jilin Province

The authors reconstructed the information of land use/coverage change(LUCC) in 1954,1976 and 2000,integrating TM,MSS and topographic map with expert knowledge in the eastern mountain area of Jilin Province based on RS and GIS.Then the spatial-temporal changing characteristics of forest landscape combining with landscape theory and its driving mechanism from natural factors,spatial postition factors and social economic factors were analyzed.The conclusion was that the forest area decreased and then it increased in the eastern mountain area of Jilin Province from 1954 to 2000.Owing to reclaiming the forestland before 1976 and protecting forests in the mountain areas after 1976,the fragmental index of landscape increased first and then decreased.Main conversion types of woodland change were forestland-farmland and forestland-grassland,and Yanbian Korean Autonomous Prefecture of Jilin Province was the main area of forest change.Woodland change mainly took place in the area of low hill and plain,whose elevation was 300-900 m and grade was(0°-11°.) The woodland change took exponential attenuation with distances from village and road and the forests were protected in the natural reserve and eco-function areas.Forest changes came from three levels of driving forces,i.e.the woodland demand with population increase and economic development,and the wrong forest industry policy were the main driving factors of forest decrease;the forest protection policy was the main driving factors of woodland increase;and the natural factors,the distances from town,village and road were important and influenced factors of spatial position selecting.