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作 者 ：马旭东,张苏峻,苏志尧*,区余端,刘刚

期 刊 ：生态学报 2010年 30卷 19期 页码：5151~5160

关键词：车八岭国家级自然保护区；微地形；群落结构；多响应置换过程(MRPP)；典范对应分析(CCA)；

Keywords:Chebaling National Nature Reserve, microtopography, community structure, multi-response permutation procedures (MRPP), canonical correspondence analysis (CCA),

摘 要 ：以车八岭国家级自然保护区南亚热带常绿阔叶林2 hm2样地调查数据为基础，根据样方排列、海拔梯度变化及水分梯度理论潜在值从低到高的趋势将样地划分为5条样带，在由山脊至山谷的微地形变化范围内对群落结构进行全面分析，探讨群落内部结构变化规律及其影响因子。研究结果表明，海拔、坡位、坡向、坡度等山地微地形条件对群落结构及物种分布影响显著。从山脊至谷底变化过程中，各样带平均树高、平均胸径以及较大高度级和胸径级的物种个体比例减少，物种多样性呈现增加趋势。多响应置换过程（MRPP）分析表明各样带之间物种组成存在极显著差异（P<0.0001），且样带主要物种及密度发生明显变化。通过物种与地形因子的典范对应分析（CCA）知，在同一区域内，物种随地形因子表现出不同的分布趋势，米锥（Castanopsis carlesii）、甜锥（Castanopsis eyrei）、石栎（Lithocarpus glaber）等喜光的阳性树种在上坡位分布较多，枫香（Liquidambar formosana）、樟叶槭（Acer cinnamomifolium）等喜温暖湿润气候的物种则在下坡位样带为优势物种。揭示了山地常绿阔叶林群落特征对微地形变化的响应，对于区域生物多样性保护和植被恢复具有重要的理论和实践意义。

Abstract:Microtopographic factors have a great effect on species composition and diversity patterns of forest communities. Understanding the relationship between microtopographic factors and species patterns will have significant implications for forest conservation and sustainable management. Based on field data collected within a 2-hm2 permanent plot (50 subplots) in the lower subtropical evergreen broadleaved forest in Chebaling National Nature Reserve, Guangdong, China, variations in community structure in response to microtopographic changes were analyzed in five transects from the ridge to the valley that were divided according to sample plot layout, elevational difference, and moisture potential gradient. With contiguous grid quadrat sampling method, species were censused by height, abundance, and percent cover for the understory layer and by height and diameter at breast height (DBH) for the tree layer. Microtopographic attributes including elevation, slope position, aspect and slope degree were also recorded on a subplot basis. The results showed that microtopographic factors had a strong influence on community structure and species distribution. Transect-based mean height and DBH and the proportion of individuals belonging to larger height and DBH class decreased from the ridge to the valley, while species diversity increased gradually. Multi-response permutation procedures (MRPP) indicated that species composition among various transects varied significantly (P < 0.0001), and the presence of dominant species and their density also differed greatly. Although tree density varied, both Castanopsis carlesii and Styrax suberifolia were dominant species on all transects. Canonical correspondence analysis（CCA）further confirmed that species had an obvious distribution trend with topographic condition. Photophilous species including Castanopsis carlesii,Castanopsis eyrei,and Lithocarpus glaber tended to distribute on the upslope, while species adapting to warm and humid habitats such as Liquidambar formosana, and Neolitsea chuii became dominant on the valley transects. The Castanopsis eyrei distribution reflected habitat conditions of a higher elevation, whereas the position of Liquidambar formosana and Acer cinnamomifolium in the CCA ordination diagram had an obvious shorter distance to the centroid of downslope. Species including Castanopsis carlesii and Styrax suberifolia, which were widely distributed in the sample plots, occupied important positions in the center of the diagram, indicating the variation in distribution was not obvious with the change of environmental gradient. This study elaborated the response of community composition and structure of a montane evergreen broadleaved forest to microtopographic changes, and will have significant implications both theoretically and in practice for regional biodiversity conservation and vegetation restoration.

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