喜马拉雅山脉种子植物海拔梯度分布格局及其影响因素

Elevational patterns of seed plants and the driving mechanisms in the Himalaya

喜马拉雅山脉为全球生物多样性的热点研究地区,探究该地区植物海拔梯度格局及其影响因素对揭示生物多样性形成和保护具有重要意义。本研究收集整理喜马拉雅山脉11886种种子植物以及不同生长型植物(7918种草本、2587种灌木和1388种乔木)的海拔分布范围,使用最优回归模型拟合得出喜马拉雅山脉种子植物物种丰富度与谱系多样性随海拔升高主要呈现单峰形曲线,所有物种、乔木、灌木、草本植物的多样性分别在约2000、1000、1600和3000 m的海拔处达到最大值。层次分割和偏回归分析结果表明,气候和地形因素共同决定着物种的海拔梯度格局,其中年均温和年均降水量对物种海拔分布的影响较大,比表面积和地形异质性对物种海拔分布的影响较小。相较于所有物种与草本植物,乔木和灌木分布格局的构建更多受到气候与地形因素交互作用的影响。

The Himalaya is an important biodiversity hotspot on earth,which is of great significance to study the elevational gradients in plant diversity and its influencing factors for further revealing the formation of biodiversity and conservation.In this study,we measured the elevational range of 11886 seed plant species and different growthforms(7918 herbaceous species,2587 shrub species,and 1388 tree species)in the Himalaya.Using the optimal fitted regression models,we found that species richness and phylogenetic diversity of seed plants in the Himalaya mainly showed unimodal curves with the increases of elevation.The species richness and phylogenetic diversity of all species,trees,shrubs and herbaceous species reached the maximum value at the elevation of about 2000,1000,1600 and 3000 m,respectively.The results of partial regression and hierarchical partitioning analysis showed that climate and topography together drove the elevational gradient in plant diversity.Among these,mean annual temperature and annual precipitation contributed greatly to the elevational pattern,while surface area ratio and topo⁃graphic heterogeneity had little influence.Compared with all species and herbaceous species,the elevational gradi⁃ents of trees and shrubs plants were affected to a greater extent by the interaction between climate and topography.