Influence of Community Structural Characteristics of Natural Secondary Forest on the Growth of the Young Trees of Pinus koraiensis

The effects of 6 environmental factors, i.e. light condition, direct sunlight, thickness of soil humus, neighboring trees, upper canopy species, herbs and shrubs, on the growth of the young trees of Pinus koraiensis were investigated taking 4 closest neighboring trees as the structural unit of the individual growth environment. The influence of 3 community characteristics factors of direct sunlight, upper canopy species, herbs and shrubs were studied in this paper.Results indicated that (1) the exposure of the tree top benefited the most to the growth of the young trees of P.koraiensis, and the direct sunlight from east,northwest,southeast and central could also benefited it; (2) upper canopy species of small leaves or sparse branches and leaves were good for the growth of the young trees of P.koraiensis; (3) the growth of the young trees of P.koraiensis were affected by the cover of the herbs and shrubs. The influence varied in different growth period. When the young trees of P.koraiensis were the underplant, their growth would be suppressed by the blooming growth of herbs and shrubs. When the young trees of P.koraiensis grew bigger, the influence of herbs and shrubs to them would be decreased.