Abstract:

By using observation data over 50 years, the paper systematically analyzed the relations of different stand density with diameter, height, crown of trees and so on. The result showed that the suitable formula for stand density under moderate site condition (index of 14) was N=21 182×D^{-1.182 7} . Stand quality was promoted by adjusting existing stand density. Compared with contrast, annual diameter and height increment were increased by 15%～20% and 5%, respectively, which would greatly reduce the duration of breeding large pole. According to investigations of plant and analyses of physical and chemical property of soils under different density, species diversity and biomass were decreased with the increase of density. Conversely, the nutrition and soil physical property were enhanced with the decrease of density. Twenty years observation indicated that seed production had direct relations to stand density and age. Based on the standard of the research, under the conditions of suitable stand density, cutting 3～4 branches and trunk at the top of tree in the first winter after abundant year, multi-tips would be gotten. As a result, multiple coning branches would be reached. Combining with pruning, wood quality could be promoted and seed production would be greatly increased. In an abundant year, cones could be increased about 39 kg·hm^-2 and net benefit could be 780 yuan·hm^-2 in a 39 a stand.

Key words: Pinus koraiensis, forest used for fruit and wood, suitable stand density, ecological effect, technique for truncation