林分密度对观赏型南方红豆杉幼树生长及形态可塑性的影响

通过调查测定福建明溪县不同密度观赏型南方红豆杉人工林幼树的生长指标和形态指标，研究其生长及形态学特征与林分密度的关系。结果表明，不同密度林分的幼树在冠长、冠幅、地径、枝下高、侧枝数量等树冠特征性状和圆满度、枝叶浓密度等观赏性状方面均存在显著差异，在树高及叶色间不存在显著差异。林分密度对生物量的分布格局有着显著影响，对不同器官生物量、生物量分配比等指标均有显著影响；单株不同器官生物量和叶枝干等器官生物量分配比，根生物量分配比和地上/地下生物量比均随林分密度增加而降低。林分密度对1级侧枝分枝角、1级侧枝数量、1级侧枝密度及平均长度有着显著影响，且随着林分密度增加而下降，幼树树冠对林分密度有着显著可塑性响应，表现出强烈的可塑性反应。

Influence of Stand Density on the Growth and Morphological Plasticity of Ornamental Taxus chinensis var.mairei Seedlings

The growth and morphological characteristics of ornamental type Taxus chinensis var.mairei saplings in plantations with different stand densities were studies by sampling measurements in Mingxi County,Fujian.The results showed that there were significant differences in crown length crown diameter,basal diameter,the lowest branch height, number of lateral branches,the vertical distribution of leaf area,ratio of crown diameter and crown length （CFR）,the dense foliage of the plant among the ornamental Taxus chinensis var.mairei plantations with different stand densities. There were no significant differences in tree height,leaf color under different stand structures.The biomass distribution pattern,different organ biomass,biomass allocation ratio,above and below ground biomass ratio of the saplings was all significantly correlated with the stand structure density.The average biomass of different organs per sapling,the biomass allocation ratio in the leaves,branches and the stem of each sapling,the root biomass allocation ratio,and the ratio of aboveground biomass /underground biomass were all decreased along with the increase of stand density.The stand den-sity played a significantly important role in controlling the first-order branching angle,the number of first-order lateral branches,the average length of first-order lateral branches,the density of first-order lateral branches,and all these in-dexes were also decreased along with the increase of the stand density,expressing the growth strategy of the highly dense stand structure that the differentiation of first-order branches was strongly inhibited to promote the stem growth.The crown structure of the saplings significantly responded to the stand density and demonstrated a strong plasticity.