Quantity and Quality Evolving on Woodland in Beijing from 1985-2000 Based on GIS

The article picks up some data on woodland in Beijing based on land use data from 1985 to 2000,analyzes the situation that different kinds of land change with varieties of woodland in GIS,and draws a conclusion that the quality of Beijing woodland is keeping fall from 1985 to 2000 although the quantity is going up.Finally the article poins out some main driving factors leading woodland evolving.