不同林龄桉树林下植被多样性分析

Species Diversity of Understory Vegetation of Eucalyptus Plantation at Different Stand Age

以广东省信宜市中部山区不同林龄(3 a生和5 a生)桉树人工林为研究对象,通过样地调查,统计和分析了桉树林下植被结构特征(种类组成、结构与分布)和物种多样性(Margale丰富度指数、Simpson优势度指数、Shannon-Wiener指数和Pielou均匀度指数)。结果表明:(1)3 a生桉树林下植被共记录维管束植物23科31属33种,5 a生桉树林林下植被共记录维管束植物24科32属35种,不同林龄桉树林下植被结构与分布特征差异较大,乔木幼苗、灌木层和草本层的优势种均明显不同;(2)林龄对桉树林下植被丰富度影响相对较小,但对优势度和均匀度影响较大;随着林龄的增加,桉树林下灌木层和草本层植被物种多样性均明显下降,其中灌木层下降幅度大于草本层。总体而言,林龄对林下植被的种类组成影响相对较小,但对林下植被的结构与分布以及物种多样性有显著影响。

Based on the field survey,the structure characteristics(species compositions,structure and distribution)and species diversity(Margale richness index,Simpson dominance index,Shannon-Wiener index and Pielou evenness index)of understory vegetation of 3-year-old and 5-year-old Eucalyptus plantation in central mountainous area of Xinyi city,Guangdong province was statistically analyzed.The result shows that:(1)There are 23 families 31 genus 33 species of vascular plants grown under 3-year-old Eucalyptus plantation,the dominant species are Sapium discolor,Evodia lepta,Cunninghamia lanceolata,Hedyotis hedyotidea,Urena lobata,Melastoma candidum,Praxelis clematidea,Dianella ensifolia,Oplismenus compositus;there are 24 families 32 genus 35 species of vascular plants grown under 5-year-old Eucalyptus plantation,the dominant species are Toona ciliata,Engelhardtia roxburghiana,Litsea glutinosa,Rhodomyrtus tomentosa,Ficus hirta,Clerodendrum cyrtophyllum,Oplismenus compositus,Dicranopteris dichotoma,Blechnum orientale.(2)For understory vegetation of Eucalyptus plantation,stand age has a limited effect on its species richness,but obviously affected its species dominance and evenness;with the increase of stand age,species diversity of shrub layer and herb layer under Eucalyptus plantation both decease obviously,and shrub layer shows a greater decrease than herb layer.In general,stand age had limited effect on the species compositions of understory vegetation of Eucalyptus plantation,but obviously affected its structure and distribution and species diversity.