广西猫儿山植物群落物种组成、群落结构及树种多样性的垂直分布格局

Changes in floristic composition, community structure, and tree species diversity of plant communities along altitudinal gradients on Mt.Mao'er, Guangxi, China

沿海拔梯度设置 16个样地 ,对广西猫儿山植物群落物种多样性的垂直分布格局进行了初步研究。结果表明 :(1) 16个样地中共调查到乔木 4 4科 79属 184种 ,其中常绿阔叶树 12 1种、落叶阔叶树 6 1种、针叶树 2种 ;(2 )随着海拔的上升 ,整个乔木层以及不同生活型的最大树高均呈显著下降趋势 ,而乔木树种的最大胸径、胸高断面积之和以及立木密度都呈现出先增大后减小的趋势 ;(3)物种丰富度在海拔 135 0m以下变化不明显 ,但 135 0m以上随着海拔的升高明显下降。在研究的海拔范围内 ,物种丰富度呈非常显著的单峰分布格局 ,最大的丰富度出现在中海拔群落中 ;(4 )α多样性沿海拔梯度的变化趋势与物种丰富度相似 ,但没有后者显著。Shannon Wiener指数(H′)和海拔之间有明显的负相关性 ,均匀度Pielou指数 (E)在取样范围内并没有随着海拔梯度的变化表现出明显的规律 ;(5 ) 135 0m以下的相邻群落之间的Jaccard指数 (CJ)大于 135 0m以上相邻群落之间的Jaccard指数 ,最小值出现在中海拔的植被过渡带。Cody指数也有类似的趋势 ,原因在于物种丰富度的变化 ;(6 )在本研究的海拔范围内 ,海拔比坡度和坡向对群落的结构特征、物种丰富度以及α多样性的影响更大。而在局部尺度上 ,人为干扰以及小地形而导致的生境异质性对群落?

We analyzed changes in species diversity of plant communities on Mt. Mao'er using data from 16 plots, which were investigated along an altitudinal gradient at 100 m intervals. Each tree (DBH> 3.3 cm) was identified and recorded. Major results were summarized as follows: (1) A total of 184 tree species from 79 genera in 44 families, among which 121 were evergreen broadleaved, 61 were deciduous broad-leaved and 2 were coniferous, were recorded. (2) Maximum height of tree layer and of different life forms decreased significantly with increasing altitude; however, maximum DBH, basal area and stem density were highest at mid-altitudes. (3) Species richness did not change greatly below 1350 m but decreased sharply with an increasing altitude, with a peak at 1350 m. (4) Alpha diversity correlated with altitude in a similar but less significant fashion compared with species richness. Diversity (H′) correlated negatively with altitude, while evenness (E) did not change notably with altitude. (5) Similarity (C J) between neighboring plots below 1350 m was larger than that above 1350 m, and the minimum similarity occurred in the transitional zone between different vegetation types. Species turnover (Cody index) paralleled patterns of community similarity (C J). (6) In the study region, altitude seemed to be the primary determinant of community structure, species richness and alpha diversity, rather than slope and aspect. Spatial heterogeneity resulting from human disturbance and micro-landform appeared to determine these characteristics at a local scale.