 The main inhabitants are Dyaks, who practice slash-and-burn rice cultivation and pan for gold on the upper reaches.The lower Kayahan flows through a rich and unusual environment of peat swamp forests, which has been severely degraded by an unsuccessful program to convert a large part of the area into rice paddies, compounded by legal and illegal forestry.Central Kalimantan covers 153,800 km2, with 82% tropical rain forest and no more than 3% agricultural land.