桂西南蚬木群落优势树种分布与环境因子的关系

蚬木(Excentrodendron hsienmu)是广泛分布于桂西南喀斯特山地的优良用材树种,了解影响蚬木群落物种分布的主要环境因子,对蚬木资源的有效保护具有重要意义。该研究基于桂西南蚬木群落的样地调查,测定了样地中乔木树种的重要值以及海拔、坡度、坡向、土壤养分等8个环境因子,采用Pearson相关分析研究了地形与土壤等环境因子间的相互关系,运用典范对应分析(CCA)方法对群落主要树种与环境因子间的关系进行了排序。结果表明:调查共记录到胸径≥1.0 cm、树高≥1.5 m的立木共176种,隶属于50科128属;群落乔木层以蚬木占绝对优势,主要伴生种有广西澄广花(Orophea anceps)、金丝李(Garcinia paucinervis)、割舌树(Walsura robusta)、苹婆(Sterculia nobilis)。相关分析显示海拔与土壤有机质、全氮间呈极显著正相关;除土壤pH之外,其余土壤肥力因子间均呈极显著正相关。CCA分析显示全钾、全磷对群落优势种的分布影响最为显著,坡向、坡度对优势种分布也具有重要作用。该研究结果揭示了影响蚬木群落物种分布的主要环境因子,为该区域的植被恢复措施提供了科学依据。

Relationship between the spatial distributions of dominant arbor species and environmental factors of Excentrodendron hsienmu community in Southwest Guangxi, China

Revealing the relationships between plant distributions and environmental factors is one focus of plant community ecology.Excentrodendron hsienmu is the endemic species in tropical limestone area,and the second national key protected plant of China,and it widely distributes in the karst mountains of Southwest Guangxi,China.Exploring factors effecting the domiant arbor trees distribution has significant implication for effectively protecting the E.hsienmu population in the study area.Important value of the main arbor species and eight environmental factors were measured based on field surveys in the karst mountains of Southwest Guangxi.And then,correlation analysis was used to detect the relationships between topographic and soil factors.Canonical correspondence analysis (CCA) was used to explore the effects of environmental factors on the distribution of dominant arbor species.A total of 176 woody plant species with diameter at breast height ≥1.0 cm,and tree height ≥1.5 m were recorded,belonging to 50 families,128 genera.E.hsienmu was absolutely dominant in tree layer,while Orophea anceps,Garcinia paucinervis,Walsura robusta,and Sterculia nobilis were the main accompanying species.Correlation analysis showed elevation was very significantly positively related to soil organic matter and total nitrogen.Except for soil pH,relationships between all soil factors were markedly positive.Result of CCA revealed that soil total potassium had the most significantly effect and the soil total phosphorus had the second on the distribution patterns of dominant arbor species,while slope aspect and degree also played important roles in the spatial patterns of them.This study revealed the main factors influencing on the spatial patterns of dominant arbor trees of E.hsienmu community,and provides scientific information for the vegetation restoration in the study area.