桉树不同种植模式的单株生长及植物多样性分析

Study on Growth Status and Plant Diversity of Different Eucalyptus Planting Patterns

为了解广西南部沿海区域桉树混交林生长状况及林下植物多样性,选取广西国有钦廉林场4年生桉树纯林和桉树混交林进行抽样调查,调查桉树树高、胸径等生长量及林下灌木植物和草本植物,结果表明:从两种模式下桉树生长量来看,混交林模式下桉树单株生长量优于纯林,桉树在混交林模式下树高比纯林高3.2m,平均胸径比纯林大1.3 cm,其树高、胸径的变异系数也大于纯林,桉树混交林的材积、蓄积量均比桉树纯林的高,分别高出6.0m^(3)、7.6m^(3);经方差分析,两种模式下桉树树高、胸径均呈现差异极显著。从混交模式下桉树与刨花润楠的生长状况来看,桉树生长速度优于刨花润楠,但树高、胸径的变异系数比刨花润楠小。从两种模式下径阶分布来看,桉树混交林径阶分布在5~18 cm,纯林径阶分布在6~14 cm,表明混交林内桉树林木径阶分布范围更广,长势相对不均匀;纯林内林木径阶分布更集中,长势相对均匀。从两种模式下林下植物多样性来看,混交林模式下物种丰富度比纯林高,灌木植物多样性指数均比纯林高,草本植物比纯林略低。整体来看,桉树与刨花润楠混交促进桉树生长量和林分质量,是生产上适合选择的混交树种。

In order to understand the growth status and understory plant diversity of Eucalyptus mixed species plantations in the southern coastal area of Guangxi,4-year-old pure Eucalyptus and mixed Eucalyptus plantation plantation forests in state-owned Qinlian Forest Farm of Guangxi were selected for sampling surveys.The results showed that the growth of Eucalyptus under the mixed forest was better than that of the pure forest,and under the mixed forest model the height of Eucalyptus was 3.2 m higher than that of the Eucalyptus in the pure forest,and the DBH was 1.3 cm larger than that of pure forest.The volume of the Eucalyptus component and the total stand volume of the mixed forest were 6.0 m^(3) and 7.6 m^(3 )higher than that of pure Eucalyptus forest respectively The variance analysis showed that there were significant differences in height and DBH between the two models.According to the growth status of Eucalyptus and Machilus flavescens under the mixed model,the growth rate of Eucalyptus is obviously better than M.flavescens,but the variation coefficient of height and DBH is smaller than M.flavescens.According to the distribution of tree diameters,the diameter range of Eucalyptus mixed forest was 5~18 cm and the diameter range of pure forest was 6~14 cm.It can be seen that the diameter range of Eucalyptus mixed forest was wider and the growth trend was relatively more variable,while the diameter range of pure forest was narrower and more concentrated with more uniform growth.The species richness of the mixed forest was higher than that of the pure forest as was the shrub diversity index,but the herbaceous plant frequency of the mixed forest was lower than that of the pure Eucalyptus forest.As a whole,the mixture of Eucalyptus and M.parvifolius seemed to benefit the growth of Eucalyptus and the quality of the forest stand,and it could be a suitable tree species combination to use for mixed species plantations.