甘肃省白龙江流域蕨类植物的多样性

白龙江流域位于甘肃南部，青藏高原东北边缘，地形复杂，气候条件多样，蕨类植物种类繁多。据调查蕨类植物有２６３种，隶属于３４科，７６属，分别占甘肃省蕨类总科数的１００％，总属数的９７．４％，总种烤的８７．６９％。本区地还发现有１６个特有种和３６个新纪录种。

The Diversity of pteridophytes of Bailongjiang River Basin in Gansu

The Bailongjiang River basin lies in the south of Gansu province and the northeast edge of Qinghai-Xizang plateau in China, where topography is complex, climatic conditions are various, and ptedridophytes are relatively abundant on species. According to that have been investigated, there are of 263 species pteridophytes and of which 16 are endemic and 36 are first recorded, which belonging to 40families and 76 genera, having a percentage of 87.96% of total species and 100% of total families, and 97.43% of total genera of the pteridophytes from Gansu respectively; The most of pteridophytes are distributed in the lower reaches of Bailongjiang River basin (including Wudu and Wengxian counties etc.), where rainwate is plentiful, climate belongs to northern subtropical moist zone and vegetational form belongs to evergreen and deciduous broad-leaved mixed forest, and it is suitable environment for the living of pteridophytes, that not only there are rich pteridophyte species but also complex floristic composition which are mainly the ones of temperate zone and include many the ones of tropica and subtropical zones. The pteridophyte flora has a close contact with thoses of tropical and subtropical zones. The study show that the center of diversity of pteridophytes in Gansu is in the lower reaches of Bailongjiang River basin.