人为干扰对川西碧峰峡山矾次生林群落结构和物种多样性的影响

为探讨人为干扰对川西碧峰峡山矾(Symplocos sumuntia)次生林群落结构和物种多样性的影响,对其群落结构、物种组成和物种多样性特征进行了研究。结果表明,在总面积为7200 m~2的12块样地中共记录到维管束植物151种,隶属于58科98属,以樟科(Lauraceae)、山矾科(Symplocaceae)、蔷薇科(Rosaceae)等为主。单因素方差分析表明,不同强度人为干扰对山矾次生林群落径级、高度级结构影响的差异不显著(P0.05),群落乔木层径级为单峰型结构,高度级结构分布呈倒“J”型,群落天然更新能力强。受不同人为强度干扰的山矾次生林群落各层次物种组成和优势种数量不同,乔木层优势种数量差异显著,且轻度干扰中度干扰重度干扰;灌木层和草本层中,中度干扰的优势种数量最多,轻度干扰次之,重度干扰的最少。总体上看,人为干扰对山矾次生林群落乔木层、草本层物种多样性水平具有负面影响,群落Shannon-Wiener多样性指数(H)、Simpson优势度指数(H′)、物种丰富度指数(S)和均匀度指数(J_(sw))随人为干扰强度的增加而降低,物种多样性水平呈下降趋势;中度干扰下灌木层的物种多样性有增加的趋势。总体上物种多样性指数表现出灌木层乔木层草本层的规律。

Effects of Human Disturbance on Species Diversity and Community Structure of Symplocos sumuntia Secondary Forest in Bifengxia in Western Sichuan

To understand the community structure and species diversity of Symplocos sumuntia secondary forest of Bifengxia in western sichuan under human disturbances, the community structure, composition of species and species diversity character of Symplocos sumuntia community were studied. The results showed that there were 151 vascular species, belonging to 58 families and 98 genera, in 12 plots with total area of 7200 m², in which Lauraceae, Symplocaceae and Rosaceae were dominant. One-Way ANOVA analysis showed that there were not significant difference (P>0.05) in diameter class and height class of tree layer under different human disturbance. And the diameter class structure of tree layer was single peak type, its height class structure conform to inverse J-shape, which suggested strong capacity of natural regeneration. The species composition and number of dominant species in each layer were different under human disturbances. The number of dominant species in tree layer had significant difference under disturbances with in order of slight disturbance > middle disturbance > severe disturbance, while the number of species in shrub layer and herb layer was in order of middle disturbance > slight disturbance > severe disturbance. The diversity indexes, such as S, H, H'', and J_sw, decreased with the increament of human disturbance, indicating a decrease of species diversity. There was negative relationship between human disturbance and species diversity in tree and herb layer, while the species diversity increased in shrub layer at middle disturbance. As a whole, these indexes were in the order of shrub layer > tree layer > herb layer.