关键词: 幼龄植株, 更新动态, 影响因素, 黑松, 海防林

Abstract:

Young trees are at the most sensitive stage to environmental stress in the life history of forest species, and they play a key role in maintaining and regenerating the population. An experiment was conducted to study the quantitative characteristics, growth dynamics of young trees and the effect of stand condition (adult tree, shrub layer and herb layer) on regeneration in Pinus thunbergii coastal protection forest in northern Shandong Peninsula. The mean density of young P. thunbergii trees was 4 024 tree·hm^-2, in a range of 50－24 300 tree·hm^-2. There was a positive exponential correlation between height and basal diameter, indicating that the young P. thunbergii population was at the rapid growth stage. Age structure of young P. thunbergii population was fairly complete, and it could be expressed as a one-humped curve. The middle-aged young P. thunbergii trees made up a large proportion, which indicated that the young P. thunbergii population stayed in a stable state currently. The height structure of young P. thunbergii population was of pyramid types, and the number of young trees decreased with increase in height grade. Most of young P. thunbergii trees were distributed in 0.3－0.9 m from a standing tree, and the number of young P. thunbergii trees decreased nearer to or far from the standing tree. Correlation analysis showed that the growth status of adult P.thunbergii trees was a driving factor to the regeneration of young trees, while shrub and herb layer had no relation to the regeneration of young trees. The forest crown closure might be a main influencing factor to the regeneration of young trees.

Key words: young trees, regeneration dynamics, influencing factors, Pinus thunbergii, coastal protection forest