罗霄山脉种子植物区系及其南北分化特征

本文基于野外调查和文献资料整理, 对罗霄山脉种子植物区系及其自北向南5条中型山脉之间的区系过渡性特征进行了系统分析。结果表明: (1)该区域内野生种子植物有179科1,107属4,314种; 区系表征科主要以亚热带山地为现代分布中心。科的区系组成为: 单型科25科, 寡种科61科, 单型属465属, 寡种属432属, 呈现出区系特征上的孑遗性, 也显示出本地区系成分与典型热带成分及典型温带成分间存在密切交流。(2)科的地理成分共分为10个类型, 以热带性成分占明显优势, 热带性科83科及温带性科40科分别占非世界性科总数的67.48%和32.52%; 属的地理成分包括15个分布区类型, 以温带成分占优势, 温带性属534属及热带性属484属分别占非世界性属总数的52.46%和47.54%。属分布区类型以泛热带分布、热带亚洲分布、北温带分布、东亚分布为主, 体现出本地区与古热带植物区系及温带第三纪植物区系的紧密联系。(3)罗霄山脉5条山脉间区系组成呈现出明显的南北分异特征, 自北向南热带属与温带属比值逐渐增大, 北段幕阜山脉温带性成分明显占优势, 与华中区系关联密切, 而南段万洋山脉、诸广山脉热带性属较占优势, 分布有丰富的华南区系成分。罗霄山脉地区是重要的区系交流通道, 历史时期的气候波动是本地区现代区系分布格局形成的主要原因。

Floristic characteristics and north-south differentiation of seed plants in the Luoxiao Mountains

This paper studied the flora of seed plants in the Luoxiao Mountains and revealed the transitional characteristics of five moderate mountains flora from north to south. The results indicated that 4,314 wild seed plants belonging to 1,107 genera and 179 families are distributed in the Luoxiao Mountains. (1) The Luoxiao Mountains flora consists of 25 families and 465 genera which distribute only one species, 61 oligotypic families and 432 oligotypic genera, presenting the relict of flora and intimate exchange between local floristic components and typical tropical and temperate components. (2) The families geographical areal-types were classified into 10 types, included 83 tropical families and 40 temperate families, accounting for 67.48% and 32.52%, respectively of the non-widespread families. The genus areal-types were classified into 15 types, including 484 tropical genera and 534 temperate genera accounting for 52.46% and 47.54%, respectively of the non-widespread genera. The distribution patterns of genera are abundant with pantropic areal-type, tropical areal-type, North temperate areal-type, and East Asia areal-type, which reflect that the flora of the Luoxiao Mountains, the paleo-tropical flora and temperate tertiary flora are strongly interrelated. (3) The floristic compositions amongst five mountains in the Luoxiao Mountains have marked spatial heterogeneity from north to south, which the R/T value, i.e ratio of tropical genera to temperate genera, increases gradually. The Mufu Mountains experienced stronger temperate elements, which are related to Central China flora, while the Wanyang Mountains and the Zhuguang Mountains contain stronger tropical elements. Climate fluctuations may be the main reason for the formation of the modern floristic distribution pattern in the region.