Study On Density Effect Of Artifical Pinus Tabulaeformis Forest In Loess Hilly Region

The artificial Pinus tabulaeformis forest of46years old in loess hilly region was studied in this article, the analysis of the growth factor,compsition of undergrowth, diversity of species,biomass, regeneration of seedlings, edaphic factor show:(1) diameter and crown width decreased with increasing of stand density,height and height under branch increased with increasing of stand density.(2)Both the species number of dicotyledonous plants and monocotyledons were the most in the low-density of artificial Pinus tabulaeformis under different stand densities.(3)The composition of undergrowth has changed because of the pressure of artificial Pinus tabulaeformis under different stand densities.The species in the low-density were the most and to be the maximum in all stand densities.Whether the number of shrub or herb is declining.Both D and H were decreasing as the increasing of stand density of artificial Pinustabulaeformis under different stand densities,The shurb evenness indexe Jsw decreased with increasing of stand density. The herb Evenness indexe Jsw also decreased with increasing of stand density.(4)The number of seedling and sapling decreased with increasing of stand density and increasing when stand density is limited.(5)The influences of soil bulk were unremarked as the very of soil depth.The result showed that soil organic matter and total N are decreasing.The change of total K was not significantly between Mid-density and High-density.The soil organic matter and total N were synchronous with the soil depth.The total K presents trend degression in the Low-density.