赣北云居山植物区系地理探讨

A STUDY ON THE FLORISTICS OF MT. YUNJUSHAN IN NORTH JIANGXI

本文探讨了云居山植物区系的起源和演化,对种子植物科、属、种的各个分布类型进行了统计分析,并与其它地区植物区系作了对比研究。该区系具有热带亲缘、温带衍生的性质;区系相当古老,残遗植物众多;地理成分复杂,特有类群丰富;区系联系广泛,间断分布多样;华东特征明显,南北区系过渡。该区系尤以华东成分最多,是华东区系的重要组成部分,与华中区系联系密切,具有中亚热带向北亚热带过渡的特点。

Mt. Yunjushan is located at the northeast end of the Jiulingshan Mts. in north Jiangxi province, which has an ancient geological history. Since the Mesozoic period, it has kept in conditions of relative stabilization and advantageous physiography. Its flora didn't suffered danger by the glacier during the Quaternary. This paper studies on the origin and evolution of the flora in geological period. Based on statistics and analysis of families, genera and species in the present flora and comparison of related regions, the flora features can be summarized as follows: 1) Mt. Yunjushan flora has the nature of the tropical consanguinity and the temperate derivation. The studies show that the tropical families are dominanting and the temperte species have the highest percentage (45.32%). The flora may be origined chiefly from an ancient tropical type during the Mesozoic and the Tertiary in ancient lands of S. China. Secondly, it may be derived from local elements and penetrated from N. temperate elements during the Quaternary. 2) The floristic origin is ancient, the flora is very rich in ancient and relic plants as well as in monotypic and oligotypic primitive types. 3) The floristic elements are complex and the endemic elements are rich. A total of 1349 species were collected from this small area (200km2) represeuting 645 genera and 144 families of Spermatophyta, of which include 3 families, 18 genera and 469 species of endemic in China, especially rich of the ancient and relic taxa. 4) The flora has extensive connection and the disjunct distribution is various. The statistical analysis of 15 distribution types in genera (Table 2) shows that the flora is related to most parts of the world, such as Trop. Asia and Trop. America disjunct 11 genera, Trop. Asia and Trop. Australis disjunct 23 genera, E. Asia and N. America disjunct 52 genera, etc. 5) The flora has obvious characted of the flora in E. China, and is transited from South to North in subtropical flora. The statistics of species shows that it has abundant elements in E. China, with 48 species of endemic in E. China. And that is very closely related to the adjacent flora of Mt. Huangshan and Mt. Dabie. Therefore, it is one of the important parts in the flora of E. China. The area is the north border of many strict tropical or subtropical plants, such as Alpinia, Helicia, Rapanea and others; It is also the south verge of some strict temperate elements, such as Cerddiphyllum, Staphylea, Myosotis, and so on. Hence, the flora has a transitive character from mid-subtropics to north subtropics in China.