Altitudinal distribution pattern and its driving factors of plant diversity in the middle section of the eastern slope of the Taihang Mountain

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.