Study on the flora of lycophytes and ferns of Siyetun Nature Reserve in Sinan County, Guizhou

Siyetun Nature Reserve is located in western part of Tongren City, and its geographic position is at longitude E 107°52′~108°28′and latitude N 27°32′~28°10′, with a total area of about 2230. 5 km2 . It has subtropical warm and humid monsoon climate, with an average annual temperature of 17. 3℃ and annual rainfall of about 1100 mm. The floristic composition and biogeographic features of lycophytes and ferns in the Siyetun Nature Reserve were analyzed according to field investigation, literature search and study of the col-lected specimens. Our results were as follows:(1) 19 families including 44 genera and 87 species(including the subspecies ) were found in the Siyetun Nature Reserve and the dominant families were Pteridaceae, Dryopteridaceae, and Polypodiaceae;(2) The floristic composition and biogeographic features are complicat-ed. The temperate species are dominant and account for 60. 92% of the total species. Among the temperate elements, 40 species were the East-Asia taxa, accounting for 45. 98%. Among the total taxa, 29 species are of tropical elements and five species are of cosmopolitan, indicating that the flora in this area have some relationship with the tropical and subtropical taxa. There are 10 species unique for China, demonstrating that the reserve has regional particularity;(3) Most areas in Guizhou Province are located in the transitional zone of plant biogeography and this is also true for the Siyetun Nature Reserve, where most genera (54. 55%) of lycophytes and ferns contain only one single species.