西藏羽藓科植物的地理分布及区系成分的初步分析

关于西藏苔藓植物的研究,过去报道甚少,据有关资料,W.Mitten(1859)整理鉴定了T.Thomson(1847-1849)在西藏西部及其邻近地区所采标本,发表了66种藓类,其中至今仍隶属于或已调入羽藓科的植物计23种,其后尚有E.S.Salmon(1900),V.F.Brotherus(1948,1929)有过报道。

A PRELIMINARY ANALYSIS ON THE GEOGRAPHICAL DISTRIBUTION ADN BRYOFLORAL ELEMENTS OF THUIDIACEAE FROM XIZANG(TIBET)

All species of family Thuidiaceae from Xizang (Tibet) areexamined and 11 genera with 28 species are reported. In accordance with a further analysis of vegetation, geo-graphical and vertical distribution of Thuidiaceae from Xizang, it may be tentatively divided into following three regions, 1. The region of southern slopes of the Himalayas. Whereunder flourish about 10 genera and 25 species as dominant elements. 2. The region of eastern Xizang. There are 7 genera and 12species. 3. The region of southern Xizang. Where there are 5 genera and 6 species. The different vertical distribution spectra of Thuidiaceae from Xizang, the author has recognized 4 distinct altitudinal zones as follows:1. The evergreen broad-leaved and deciduous broad-leaved forest zone (800-3000m. alt.). There are 23 species. 2. Subalpine coniferous forest zone (3000-3500m.). There are 17 species. 3. Alpine shrub-meadow zone (3500-4900m.). There are 12 species. 4. Till desert zone. Only 1 species distributed in this zone. The bryoflora of Thuidiaceae in Xizang consists of the following geographical elements:(1) Holarctic elements:8 species, approximating to 28.6% of the total number of Thuidiaceae in Xizang. (2) East Asiatic elements (including Sino-Japanese, Sino-Himalayas elements.); These species total up to 13 species, being 46.4% of all the Thuidiaceae in Xizang. (3)Old world tropic elements:2 species, approximating to 7.1%of all the Thuidiaceae in Xizang. (4). Endemic elements:2 species, approximating to 7.1% of all the Thuidiaceae in Xizang. (5) cosmopolitan elementas:3 species, approximating to 10.7%of all the Thuidiaceae in Xizang.