武陵山区蕨类植物研究

武陵山区蕨类植物资源丰富,现知有644种(包括变种),分属116属, 46科;蕨类区系属热带-亚热带山地类型;属的地理成份有12种类型,与日本、印度-马来西亚有密切关系;武陵山区蕨类区系属我国西南区系,与华中华东区关系密切,华南、华北区次之;蕨类垂直分布分四带。

STUDY ON THE FERNS AND FERN ALLIES OF THE WULING MOUNTAINS

Wuling Mountain range is situated at northern latitude 27°04'~30°21' and east longitude 107°52'~111°27'.The total area of Wuling Mountain range district is about 84000sq.km.According to our collecting material from 1986 to 1992, the pteridophyte flora consists of 644 species (including varieties), 116 genera and 46 families.1.The numbers of families, genera and species.In the fern flora of Wulingshan, the principal families are as follows:Dryopteridaceae, Which has 164 species, comprising about 24.9% of the total; Polypodiaceae, with 84 species, Athyriaceae, with 79 species, Thelypteridaceae, with 52 species.These 4 families provide about 58.9% of the total species.Of the rest, 5 families have 21-33 species, 8 families have 6-14 species, 15 families have 2-5 species, 14 families have only one species.Among the 116 genera of Wulingshan, the following genera have the high number of species:Dryopteris (50 species), Polystichum (44 species), Arachniodes (34 species), Athyrium (33 species), Asplenium (33 species), Pteris and Selaginella (23 species), Coniogramme and Cyrtomium (21 species).7 genera include 10-16 species, 21 genera include 5-9 species, 36 genera include 2-4 species, 43 genera have only one species.2.Geographical elements.The geographical distribution of genera in the Wulingshan pteridophyte flora can be divided into 12 elements (or types).The major element is Asian, with a total of 35 genera, constituting about 34.3% (excluding cosmopolitan genera).There are 116 genera in the Wulingshan pteridophyte flora, 76 genera have a tropical-subtropical distribution, 24 genera temperate distribution, the genera with tropical-subtropical distribution represent 74.5% (excluding the cosmopolitan genera).The Wulingshan flora clearly belongs to tropical-subtropical montane one.The fern-flora of Wulingshan and Japan is closely related (there are 108 genera in common).They bear some resemblance to the Indo-Malaysian flora and have the least similarity to those of America and Australasia etc.The major elements of the Wulingshan pteridophyte flora are those of Southwest China.This flora has much in common with that of East China and Middle China, with some similarity to that of South China and North China, it has least resemblance to the floras of the Northeast and the Northwest.The endemic species of Wulingshan fern-flora, are 29 species, comprise about 4.5% of the total species.3.The vertical distribution of pteridophytes.The vertical distribution of pteridophytes in Wulingshan may be divided into four zones:(1) The evergreen broad-leaf forest zone (below the alt.of 1000-1300m.).(2) The evergreen and deciduous broad-leaved mixed forest zone (alt.the of 1000-1500m.).(3) The deciduous broad-leaved forest zone (alt.the of 1500-1900m.).(4) The grassland and bush zone (alt.over 1900m.).