广西乐业大曹天坑维管植物地理成分及区系基本特征

大曹天坑维管植物种类相对较丰富,种群类型多样化,开展天坑内植物区系及地理成分分析研究,对天坑生物多样性的保育及区系研究具有重要意义。调查结果表明:大曹天坑共分布蕨类植物13科19属27种;种子植物有85科155属209种;单子叶植物9科22属28种,双子叶植物76科133属181种。从科属的分布区类型分析可知,其泛热带分布及其变型的科、属所占比例都是最大的,优势种群比较多,其他热带分布也有相当大的比例。温带地理成分的科属在本区系中也具有较大比例,北温带分布仅次于泛热带分布,带有明显的温带区系成分。本区系具有较明显的温带区系向热带区系过渡的特点以及热带北缘的区系性质,但整体特有成分程度相对低。

Geographical Constituents and Basic Floristic Characteristics of Vascular Plants in Dacao Tiankeng of Guangxi Leye

Vascular plants in Dacao tiankeng are relatively abundant in species and the population types are diversified.Carrying out the analysis of flora and geographical components is of great significance to the biodiversity conservation and flora research in tiankeng.The investigation results show that ferns in Dacao tiankeng are distributed in 13 families,19 genera and 27 species.Seed plants are distributed in 85 families,155 genera and 209 species.Monocotyledons are distributed in 9 families,22 genera and 28 species.Dicotyledons are distributed in 76 families,133 genera and 181 species.It can be known from the areal type analysis of family and genus that the pantropical areal types and their variations account for the largest proportion of families and genera.There are more dominant populations,and other tropical areal types also have a considerable proportion.Families and genera of temperate geographical components also have a large proportion in this region,and the areal type in northern temperate zone is second only to the pantropical areal type,with obvious temperate components.The results show that this region has a more obvious characteristic of transition from temperate zone to tropical zone and the floristic nature of the northern margin of tropical zone.However,the overall degree of reflecting the endemic components is relatively lower.