丹霞地貌桫椤群落结构特征及其多样性的垂直变化

Composition Characteristics of Alsophila spinulosa Community and Vertical Change on Species Diversity in Danxia Landform

为了探讨丹霞地貌区桫椤群落物种的多样性,利用物种丰富度指数、物种多样性指数和物种均匀度指数对习水长嵌沟景区内桫椤群落物种的多样性进行了测定和分析。结果表明:样地为亚热带常绿阔叶混交林的桫椤+贵州琼楠-粗糠柴-线柱苣苔群丛;样地内共有植物82种,其中乔木31种,灌木31种,草本17种,木质藤本3种,隶属39科56属;整个样地共有乔木317株,其中桫椤有153株,重要值为0.531 3,属于乔木层的优势种,是整个群落的建群种;灌木层和幼苗层的植株很少。90%的植株高度集中在9m以下,3～6m的植株最多;整个群落中随着树高的增加,植株的数量呈减小趋势;胸径级总的变化趋势是随着胸径等级的增加植株数量呈下降趋势。丰富度指数和Shannon-wiener指数乔木层显著大于灌木层和幼苗层,Simpson指数和均匀度指数为乔木层>灌木层>幼苗层,但是差异不显著。随海拔梯度的变化乔木层的丰富度指数始终大于灌木层和幼苗层,灌木层的几个多样性指数的变化趋势总体一致,呈现出减小→增大→减小→增大的变化;海拔620m处乔木层的Shannon-wiener指数和均匀度指数小于灌木层;海拔770m处灌木层的SW指数、SN指数、PW指数和R指数都为最低值,SW灌=0,SN灌=0,PW灌=0,R灌=0.5;海拔670m和770m处SW指数和R指数变化趋势相反。海拔670m和770m的相似性最大,CJ=0.394 7,相似性最小的是620m和770m,CJ=0.183 3。

In order to study the species diversity of A.spinulosa community in Danxia Landform,an investigation of A.spinulosa community was conducted in Chang-Qian-Gou scenic spot of Xishui,Guizhou Province.Species richness index,Shannon-wiener index,Simpson index and Pielou＇s evenness index were used in this investigation and analysis.The results showed that the sample plot was a association of subtropical evergreen broadleaf mixed forest： Ass.Alsophila spinulosa＋Beilschmiedia intermedia-Mallotus philippinensis-Rhynchotechum obovatum.The results indicated that the sample plot was made of 82 plant species,including 31 species in tree layer,31 species in shrub layer,17 species in herb layer,and 3 woody climbers,belonging to 56 genera and 39 families.There were 317 trees in this sample plot,including 153 A.spinulosa that important value was 0.5313.A.spinulosa was the dominant species in tree layer,and constructive species in whole plots.The numbers of plants in shrub layer and seedling layer were very little.The height of 90% of plants was at a concentration of 0 ~ 9 m,and the most plants were in the height of 3 ~ 6 m.The numbers of plants decreased as height classes raised;the number of plants decreased as diameter classes raised in a general tendency.The species richness index and Shannon-wiener index of tree layer was significantly greater than shrub layer＇s or seedling layer＇s.The tendency of Simpson index and Pielou＇s evenness index are as follows： tree layershrub layerseedling layer,but no significant differences compared with each other.The Species richness index of tree layer was always greater than shrub layer＇s or seedling layer＇s with the increase of altitude.The general change of these diversity indices of shrub layer with the increase of altitude tends to be uniform,show that： decreasing→increasing→decreasing→increasing.The Shannon-wiener index and Pielou＇s evenness index of tree layer at 620m was less than shrub layer＇s.The Species richness index,Shannon-wiener index,Simpson index and Pielou＇s evenness index of shrub layer at 770m was the least,,SW shrub=0,SN shrub=0,PW shrub=0,R shrub=0.5,and the tendency was reversedbetween Shannon-wiener indexand Species richness index of shrub layer at 670m and 770m.The Jaccard coefficient was the largest between 670m and 770m,CJ=0.394 7,and the least was between 620m and 770m,CJ=0.1833.