广西马尾松人工林林下木本植物径级结构特征

Diameter Structure Characteristics of Understory Woody Species in Pinus massoniana Plantations in Guangxi

关键词:  马尾松人工林  林下木本植物  径级结构  林龄  造林密度  气候条件

Key words:  Pinus massoniana plantations  understory woody species  diameter structure  forest ages  planting densities  climatic conditions

摘要:

为了解广西马尾松Pinus massoniana人工林林下木本植物的径级结构特征，采用样地调查法对马尾松人工林林下木本植物进行每木调查，分析不同林龄、不同造林密度和不同气候条件的林下木本植物径级结构。结果表明：（1）不同林龄马尾松人工林林下木本植物径级结构皆有不同，随着近自然恢复的进行，阔叶树密度、径级和木本植物个体之间分化程度呈先减小后增大的趋势，过熟林林下木本植物个体生长分化程度最高；（2）两种造林密度中，高密度林林下木本植物株数更多，胸径分化程度更大，生境多样性更高；（3）在不同气候条件下，随着纬度的降低，马尾松人工林中龄林和过熟林林下木本植物的平均胸径增大，且生长分化程度变低。初步研究发现，马尾松人工林随着近自然恢复的进行具有演替为地带性顶极群落的趋势。相对较大的造林密度有利于马尾松人工纯林林下木本植物生长，不同气候条件对马尾松人工林林下木本植物的径级结构有着明显影响，水热条件相对更丰富的北热带气候林下木本植物生长更好且个体分化程度更低。

Abstract:

In order to understand the diameter structure characteristics of understory woody species in Pinus massoniana plantations in Guangxi,the method of sample plot investigation was used to investigate the understory woody species in P.massoniana plantations for each tree to analyze the diameter structure of understory woody species at three aspects of different forest ages,different planting densities and different climatic conditions.The results showed that: (1) the diameter structure of understory woody species at different forest ages of P.massoniana plantations was different.With the progress of near-natural restoration,the density of broad-leaved trees,the number of diameter classes and degree of differentiation among understory woody species showed a trend of decreasing first and then increasing,and the individual growth diversity of understory woody species reached the highest level in overripe forests.(2) Among two planting densities of P.massoniana plantations,the number of understory woody species under high density forest was more,the degree of differentiation of the diameter DBH,was greater,and the diversity of habitat was higher.(3) Under different climatic conditions,the average DBH of understory woody plants increased and the degree of growth and differentiation decreased in the middle-aged and overripe forests of P.massoniana plantations as the latitude decreased.It was initially found that the P.massoniana plantations had a tendency to succeed to zonal climax communities as the near-natural restoration progress.P.massoniana plantations with relatively large planting density were beneficial to accelerate the growth of understory woody species.Different climatic conditions had obvious effects on the diameter structure of understory woody species of P.massoniana plantations.The northern tropical climate with more abundant hydrothermal conditions made the understory woody species grow better and the individual differentiation degree lower.