Altitudinal distribution pattern and its driving factors of plant diversity in the middle section of the eastern slope of the Taihang Mountain
摘要: 太行山东西坡因地形等因素差异呈现不同的生物多样性, 本文聚焦于太行山东坡中段, 研究了植物多样性在海拔梯度上的分布格局及其主要影响因素。根据样方调查数据, 研究了维管植物α多样性和β多样性的垂直分布格局, 由此描述了植物群落的垂直梯度演替特征; 应用植被净初级生产力(MODIS NPP)数据产品, 分析了垂直梯度植物丰富度与净初级生产力(NPP)和环境因子之间的关系; 运用数量分类学方法, 研究了主导群落优势物种垂直分布的环境因素。结果表明: 太行山东坡中段维管植物群落α多样性垂直分布出现两次峰值, 基本符合“中间高度膨胀”理论。植物多样性垂直分布与太行山区产水量和NPP垂直格局相一致。β多样性相似性指数在物种丰富度峰值区达到最低, 说明此区段群落间差异性大, 群落间演替速率增大, 致使群落物种多样性增加。植被NPP与物种丰富度呈现一致的垂直分布格局, 二者显著正相关。RDA和CCA排序分析表明, 影响优势物种垂直分布的主要环境因素是海拔、温度和降水, 与坡度、坡面等地形因子相关性不显著。综合研究结果, 太行山东坡中段维管植物垂直分布格局是群落垂直演替进程、环境因素和人为干扰协同作用的结果。Abstract: Due to global climate change, altitudinal distribution patterns of biodiversity and factors influencing biodiversity have changed dramatically. To clarify the elevational distribution pattern of plant diversity and the main influencing factors in the middle section of the eastern slope of the Taihang Mountain, the alpha and beta diversities of vascular plant communities were studied along the elevational gradient using the quadrat survey method. In the middle section of the eastern slope of the Taihang Mountain, the succession characteristics of plant communities along the elevational gradient were investigated. Additionally, the main factors influencing the altitudinal distribution pattern of plant diversity were studied. The possible mechanisms of plant altitudinal distribution patterns were discussed by exploring the relationships between plant diversity and environmental factors. The results showed that the distribution of the alpha diversity of vegetationa had two peaks along the elevational gradient, which was in line with the theory of “diversity peaks at the intermediate altitude”. By studying the correlation between plant diversity, water yield, and net primary production of vegetation along the altitudinal gradient, it was demonstrated that the distribution pattern of plant diversity on the elevational gradient was consistent with the vertical distribution pattern of water yield and net primary productivity of vegetation in the study area. The similarity index (beta diversity) of plant communities on the altitudinal gradient reached the lowest value in the peak area of species richness, indicating that there were significant differences among the plant communities within this height range, and that the replacement rate of plant species between communities increased, which led to an increase in plant species richness. The altitudinal distribution of net primary production of vegetation showed a consistent pattern with plant species richness in the study area, and there was a significant positive correlation between them. CCA and RDA analyses revealed that the main environmental factors influencing the distribution of plant diversity on the elevational gradient were altitude, temperature, and precipitation; and no significant correlation was found with topographic factors such as slope and aspect. Comparing the ordination results of CCA and RDA analyses, the results were found to be consistent, which proved that both the linear and unimodal models were suitable for the ordination study of plant species distribution in this region. Using the Monte Carlo permutation test, the significance of the explanatory quantity of environmental factors on species distribution was analyzed. The results showed that the ordination results can comprehensively explain the effects of various environmental factors on species distribution. Based on the comprehensive research results, it was concluded that the altitudinal distribution pattern of the vascular plants in the middle section of the eastern slope of the Taihang Mountain was the result of the synergistic effect of the community altitudinal succession processes, environmental influence, and human disturbance.
图 2 太行山东坡中段维管植物群落丰富度和种群密度(a)、α多样性(Shannon-Wiener指数)(b)、相似性指数(Sørensen和Jaccard指数)(c)和群落更替速率(Cody指数)(d)的垂直分布
Figure 2. Altitudinal variations of the species richness and density (a), alpha index (Shannon-Wiener index) (b), similarity index (Sørensen and Jaccard indexes) (c) and succession rate (Cody index) (d) of vascular plant communities in the middle section fo the eastern slope of the Taihang Mountain
图 4 太行山东坡中段植物群落优势物种RDA和CCA排序图
sit1-sit16: 取样点1到取样点16。T: 温度; prec: 降水; ele: 海拔; asp: 坡向; slo: 坡度; N: 土壤全氮含量; P: 土壤全磷含量; K: 土壤全钾含量; C: 土壤全碳含量; por: 土壤孔隙度。Rubia: 茜草属; Ailanthus: 臭椿属; Populus: 杨属; Ziziphus: 枣属; Pinus: 松属; Potentilla: 委陵菜属; Thalictrum: 唐松草属; Ampelopsis: 蛇葡萄属; Saussurea: 风毛菊属; Spiraea: 绣线菊属; Artemis