[Landscape pattern change and its driving forces in middle and upper reaches of Dongting Lake watershed].

Based on GIS and RS, the landscape pattern change in the middle and upper reaches of Dongting Lake watershed from 1980 to 2000 was studied, with its driving forces analyzed. The results showed that there was a remarkable difference in the area change of various landscape types, with the sequence of forest land > mountain paddy field > open forest land. This change mainly occurred in mountainous and hilly areas, and had a decreasing trend from the east to the west, i. e., decreased in the order of Xiangshui River valley > Zishui River valley > Yuanshui River valley > Lishui River valley. The patch shape was simple and regular from 1980 to 1995, but diversified from 1995 to 2000. The main driving forces of the landscape pattern change were the pressure of booming farming population on natural ecosystem, the dependence of watershed' s development on natural resources, the investment to protect and improve the functions of natural ecosystem, and the adjustment of agricultural polices.