A major cause of deforestation in China is the production of commercial lumber; as with the Heilongjiang province which produced 465 million meters3 from 1949 to 1986. Another contributor is slash-and-burn agriculture. This type of farming destroys 62,000 ha. Another 6,000 ha. were cleared for the cultivation of silkworms and mushrooms. Additionally, 125,000 ha. were cut down for railroads, highways, and high voltage lines. Lastly, 47,000 ha. burned down in forest fires.