DI 47 the vegetation coverage across the world

The map shows the vegetation coverage across the world of three main ages. The green color means closed forest (which is over 70% plant cover) while the yellow color represents extreme desert (which has less than 2% of vegetation cover). About 18,000 years ago,in the last glacial maximum, ）the extreme desert coveredhuge areas including North Africa, the middle east and southern part of Australia. Roughly 8000 years ago, closed forest exist in most part of America, central Africa, east Asia and Europe. At present, the distribution of closed forest remains almost the same areas,but extreme desert appears in North Africa, and middle Asia.