Soil and Water Conservation Function of Pinus tabulaeformis Plantation in the Forest Zone of Loess Plateau

Soil and water conservation functions of Pinus tabulaeformis plantation in the forest zone of Loess Plateau were investigated by long term observation,establishment of standard artificial runoff and sediment modulus.The results showed that(1) soil erosion amount on farmland was 908,97,and 58 times more than those of natural P.tabulaeformis forest land,land of cutting trees and keeping bushes and grasses,land of clearing ground litter cover and keeping trees and bush during 14 years,respectively.(2) The sediment concentration of farmland was 81,35,and 46 times more than those in the three kinds of lands mentioned above,respectively during 14 years.(3)The mean annual runoffs in the land of undisturbed P.tabulaeformis stand and the land of cutting trees and keeping bush and grass were 0.137 and 0.122 times more than that of the farmland,respectively.(4) Comparison between runoff and rainfall,sediment concentration and rainfall intensity showed significant correlation on different types of land.