檫树毛竹混交林中毛竹鞭根的研究

采用固定标准地定位观测法，对新造竹林中栽植擦树后形成的檫树（14－15年）毛竹混交林竹鞭根结构和鞭体养分进行了调查和测定，结果表明，檫树在一定的密度范围，混交竹林有利于毛竹鞭根结构的优化和鞭体养分的提高，与毛竹纯林相比，檫树密度为420－615株.hm^-2的混交竹林，其鞭长，鞭径及其整齐度，新鞭年生长量，壮幼鞭比例，健壮芽数量、鞭根体积等，均在不同程度上高于毛竹纯林中的对应部分。当檫树密度超过735株.hm^-2时，混交竹林中的上述指标则低于生毛竹纯林中的对应部分，但单位鞭长的分岔次数明显加大，回归分析表明，鞭总长，鞭节点，新鞭生长量，鞭径、鞭径整齐度及单位鞭长分岔次数与檫树密度之间的关系密切（r=0.92956-0.99530)，混交竹林中鞭体的N、P、K,Ca,Mg养分含量高于纯柯的对应值，其中鞭体中N含量较纯林平均高出7．6％、11．6％。

Bamboo rhizome system of mixed forest of Sassafras tsumu and Phyllostachys pubescens

By the method of fixed plots, the bamboo rhizome system structure and nutrient content in rhizome from mixed Sassafras tsumu and Phyllostachys pubescens, which were established in 1983-1984 by planting S. tsumu on new-planted bamboo forests (3-4 years old), were investigated. The results showed that the mixtures with rational density of S. tsumu were suitable for optimizing the bamboo rhizome structure and increasing the nutrient content in rhizome. The total length and weight of rhizome, the diameter of rhizome and its evenness indices, the annual growth of new rhizome, the proportion of healthy rhizomes and buds, and the volume of rhizome system in the mixed bamboo forests with the density of 420- 615 S. tsumu trees per hectare were higher than those in pure bamboo forest, respectively . The indexes mentioned above in mixed bamboo forests with the density of S. tsumu more than 735 trees per hectare were lower than those in pure bamboo forest, respectively, but the frequency of rhizome branch per unit length of rhizome was obviously higher than that in pure bamboo forest. The results of regression analysis showed that there were close relationships between S. tsumu density and total length of rhizome, the length between two joints, the growth of new rhizome, the diameter of rhizome and its evenness indices, and the frequency of rhizome branch per unit length of rhizome. The content of N, P, K, Ca, and Mg in the rhizome from mixed bamboo forests were higher than those in pure bamboo forest, respectively. For example, the content of N in rhizomes from mixtures was increased by 7.6-11.6% averagely.