濒危树种钟萼木当年生苗木生长空间分布与生物量分配研究

利用苗木群体高与地径生长呈正态分布规律,根据"正态分布标准差分类法",以群体标准差值做为不同生长类型划分标准,把钟萼木当年生苗高生长个体划分为8个生长类型,取每一生长类型代表样本进行生长空间分布和生物量分配研究,结果表明,不同样本地上部分的水平空间分布基本相接近,大的样本个体在垂直方向上占据更多空间,对下层个体产生侧方空间与光照竞争。该树种苗木根系发达,主根生长明显,侧根与须根生长旺盛,地下部分水平空间分布随着个体生长量增大,侧根在水平空间形成竞争。不同样本的各组织生物量分配表明,根部与杆的生物量生长比例相近,但生长类型好的样本根部的皮生物量占比例更大,这与须根生长量加大有关。生长类型较好样本树杆的木质部生物量所占比例加大,树干的皮生物量比例增加不明显,叶生物量明显增加,但在全株样本生物量所占比例减少,叶生物量占全株样本生物量比例大。

The Growth Spatial Distribution and Biomass Allocation of the Endangered Tree Species Bretschneidera sinensis Hems1.at Current Year

The height and stem diameter of populations of seedlings show a normal distribution.The standard deviation values of populations of Bretschneidera sinensis Hems1 were used as a classification standard for growth types.The seedling individuals of B.sinensis Hems1 were classified into 8 growth types at the current year of growth,from which individuals of each growth type were sampled as a representative to observe their growth spatial distribution and biomass allocation.The results indicated that the above-the-ground growth of the representative sample seedlings of different growth types was generally the same in horizontal space distribution,and that the larger representative sample individuals took more space vertically and had a lateral space to compete sunlight with the undergrowth individuals.B.sinensis Hems1 had a well-developed rooting system,with an obvious growth of tap root and exuberant growth of lateral and fibril roots.For the horizontal spatial distribution of the underground part of the seedlings the lateral roots competed with each other in the horizontal space as the growth of the individuals increased.Tissue biomass allocation of different sample individuals showed that the seedlings had similar proportion of biomass growth in roots and stems,but the sample individuals of the good growth type had a larger proportion of the roots in bark biomass,which was related to the increased growth of fibril roots.For sample individuals of the better growth type the xylem biomass had a larger proportion in the stem,the stem bark biomass did not increase obviously,and the leaf biomass increased remarkably but had a small proportion of biomass in the whole plant.