Dynamic Land Use Changes in the Poyang Lake Region over the Recent 17 Years
1989年至2006年鄱阳湖区土地利用动态变化研究

Land use change is one of hot topics of global environmental change. Its research is of significance for reasonable use of land resources and effective protection of the environment. Based on GIS and Landsat TM images, the authors analyzed structural features and spatial patterns of land use changes in the Poyang Lake region over the recent 17 years. Results showed that the composition characteristics of the land system changed slightly, but the internal structure of the land system changed obviously due to the combined influence of human activities and natural factors. During the period 1989-2006, the cropland, woodland, and water bodies were prevalent, with the total area of the three land use types over 75% of the total area of the region. The area proportion of construction land and unused land were essentially small, with their total area smaller than 8% of the total area. Cropland, water bodies, and unused land were reducing significantly during the study period based on change detection performed, whereas the relative change of cropland was slower than others in terms of the value of the land use dynamic degree because of its large proportion. The area of construction land and bottomland increased to a certain extent, and the relative change of construction land was the fastest in all land use types. Areas of woodland remained the least changes. Each land use type transferred within each other during different study periods were analyzed based on the transfer matrix of land use types. Water bodies were converted principally into grassland and bottomland. On the other hand, water bodies were mainly converted from cropland as a result of the influence of policy about Poyang Lake protection. Woodland, grassland, and cropland were transferred frequently within each other. This indicates that human activities which might be detrimental to the ecosystems and the environment may have taken place when the policy of environment protection was being implemented. Increases in construction land areas were primarily caused by the occupancy of cropland and grassland. Changes in bottomland were mainly determined by water levels and human farming activities. The bottomland was mainly converted into cropland and grassland during the period 1989-1999 and to cropland and water bodies during the period 1999-2006. However, it was mainly transferred from water bodies and cropland in the two periods. Unused land was transferred slightly with other land use types, showing a fairly invariant spatial distribution. Furthermore, the land use efficiency of the Poyang Lake region were significantly improved due to industrial structure adjustments and ecological restoration, with the land use mode changing from extensive use to intensive one.