关键词: 同一系数, 同一系数

Abstract: To understand the distribution and characteristics of wild pteridophyte resources in North China, find out similarity of ferns between different districts, and provide scientific basis for introduction of ferns, this paper adopted the literature statistics combined with field investigation method, and analyzed the relationship between the fern flora in North China according to the similarity coefficient calculation formula proposed by Sprenson. The results showed that the distribution of 146 species of pteridophytes (including 9 varieties and 2 forms), belonged to 24 families, 44 genera. The ratio of fern families, genera and species in North China to the total ferns in China, respectively, was 38.10% , 19.30% and 4.87% . Dominant families were Athyriaceae, Dryopteridaceae, Aspleniaceae, et al. There were 8 dominant families that contained more than 10 kinds of ferns, which included 24 genera and 108 species, accounting for 73.97% of the total number in the area. Dominant genera were Asplenium, Selaginella, Equisetum, et al. There were 5 dominant genera that contained more than 10 kinds of ferns, which included 54 species, accounting for 36.99% of the total number in the area. Fern species in North China was not rich, but the geographical composition was diverse, temperate components were the dominant, tropical composition only occupied a certain proportion. The unigeneric and monotypic genus were more, and the advantage phenomenon was obvious. Most of ferns were lithophytes, next were native plants, and hydrophytes and epiphytes were few. The species similarity of different districts was big; the similarity coefficient of Beijing and Hebei was 81.8%.