Abstract:

Based on the analysis of land use data obtained from six Landsat TM and ETM images in the years of 1989,1999 and 2009,this paper took advantage of the hierarchical classification method and the method which is combined with the supervised classification and the artificial visual interpretation to extract landscape class information of land use in the Chaohu Lake Basin.Further more,the Fragstats software was utilized to analyze the changes of landscape pattern during 20 years and to study its change regulation and variation characteristics.The results are as follows.(1) From 1989 to 2009,the area of construction land in the Chaohu Lake Basin increased 38 380 hm2 and the dynamic degree was up to 18%,while the cultivated area reduced 34 230 hm2.The area of water was relatively stable.The area of evergreen forest increased 40 350 hm2,and on the other hand,the area of deciduous woodland decreased 6 760 hm2.Besides,the increase area of urban construction land was major derived from the change of farm land and other types of land use.(2) The numbers of plaque (NP) and the patch density (PD) made a linear reduction during 20 years,and all the decline rates were about 22%.With respect to the block shape index (LSI),it decreased quickly as its rate was about 28%.Moreover,the largest patch index (LPI) showed that the change rule of V shaped,and the aggregation index (AI) was steady rising,so that it illustrated that the landscape change was affected more and more by human activities.(3) In terms of the types of landscape,the numbers of plaque (NP) and the patch density (PD) showed a decreasing trend from 1989 to 2009,the decline extent of which was nearly one half.The principal factors to make the numbers of plaque (NP) as well as the patch density (PD) descend were evergreen forest and other land.At the same time,the reduction of block shape index (LSI) was caused by farm land and other land.(4) With the changes of administrative division in the Chaohu Lake Basin and the rapid development of economy,great changes of the land use will be happened in the Chaohu Lake Basin.This paper will set up a background record of new developing pattern in order to provide social and economic development planning in the Chaohu Lake Basin with the scientific theory support in the future