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 density 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 indexes 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.