In the west, the altitude can vary from the mountain peaks to river valleys by as much as 3,000 metres (9,800 ft). Yunnan is rich in natural resources and has the largest diversity of plant life in China. Of the approximately 30,000 species of higher plants in China, Yunnan has perhaps 17,000 or more.[1] Yunnan's reserves of aluminium, lead, zinc and tin are the largest in China, and there are also major reserves of copper and nickel.