山西太岳山脱皮榆群落的生态梯度分析及环境解释

Ecological Gradient Analysis and Environmental Interpretation of Ulmus lamellosa Communities in the Taiyueshan Reserve, Shanxi

为了解释山西太岳山脱皮榆(Ulmus lamellosa)群落中物种的分布情况与该群落环境因子之间的相互关系,采用TWINSPAN数量分类和典范对应分析(CCA)与环境因子的变量分离进行讨论。结果表明,TWINSPAN将60个调查样方划分为7种群丛类型,体现了该脱皮榆群落主要以乔木脱皮榆和草本披针叶苔草(Carex lanceolata)为优势种。7种群丛类型与CCA排序结果一致,CCA排序第1轴主要体现了坡位和海拔;坡向与第2排序轴存在显著相关性。Monte Carlo检验结果表明,影响脱皮榆群落物种分布最主要的环境因子是海拔。在环境分离变量解释方面,环境因子解释了39.60%,空间因子解释了7.95%,空间因子与环境因子交互作用解释部分占10.89%。而其中不能解释的部分占41.56%。在该研究区,海拔对植物的分布有较好的解释力,其次是坡位和坡向。

Many practices in afforestation and Ulmus lamellosa forest management were implemented for addressing the issues of tree species selection, planting regimes and development of structure. However, little is known about the ecological gradient and its relation with environment. We aimed to determine the factors controlling plant distribution and the importance of topography in determining local-scale spatial patterns of plants. The occurrence and distribution of plants were investigated on 60 plots in the Taiyue Mountain Reserve, Shanxi. Association types were classified by two-way indicator species analysis（TWINSPAN） and the relationship between the distribution and abundance of species and environmental gradients was analyzed by the canonical correspondence analysis（CCA） ordination method. Forward selection and Monte Carlo permutation tests were used to select the factors important in determining the plant distribution. The 60 survey plots were classified into seven groups characterized by the dominant tree species. The results of CCA ordination reflected the relationship between association structure and selected environmental variables. The distribution of 60 plots in CCA ordination was consistent with the results of TWINSPAN. Forward selection and Monte Carlo testing suggested that slope, slope position and elevation were the most important factors determining plant distribution. The effects of environmental factors, spatial factors and their interaction on the total variation of the U. lamellosa community pattern were quantitatively partitioned and showed that the contribution rates were 39.60%, 7.95%, 10.89% for environmental factors, spatial factors and their interaction, respectively, and 41.56% for other undetermined factors. Other unmeasured factors such as human activities and random events could play a role in determining the occurrence and distribution of herbaceous plants on the forest floor. Species coexistence was controlled by both niche differentiation and unified neutral theory of biodiversity.