河北围场早中新世藓类化石的植物地理学意义

摘要

Based on the study of fossils and modern distribution of mosses Leptodictyum riparium, Drepanocladus subtrichophyllus, Am⁃blystegium varium from the Guangfayong section, Weichang area, Hebei Province, the authors found that these mosses first appeared in Weichang area in the Early Miocene (22.1Ma), and they were possibly derived from Eastern Asia of Laurasian. Then, the mosses spread eastward to North America through Beringia and westward to Western Europe along Eurasia. Until the Holocene, they were mainly distributed in the North Hemisphere. Mosses of Leptodictyum riparium and Amblystegium varium further spread southward to South America and Australia since the Holocene, and gradually formed modern distribution framework, and the geographical distribu⁃tion framework of Drepanocladus trichophyllus was formed in Holocene. The phytogeographical significance concerning origin and spread of these mosses is discussed in this paper.%对河北省围场地区广发永剖面藓类植物薄网藓Leptodictyum riparium、似叶镰刀藓Drepanocladus trichophyllus和多姿柳叶藓Amblystegium varium的古地理及其对应的现代植物地理分布研究显示，这些植物最早出现于早中新世的围场地区，可能起源于该时期的古北大陆，东亚为起源中心。之后向东通过白令陆桥扩散到北美，向西沿欧亚大陆扩散至欧洲西部，至全新世时主要分布在北半球。全新世后，薄网藓与多姿柳叶藓进一步向南扩散，分别由北美及亚洲东部扩散到南美洲及澳大利亚地区，逐步形成现在的分布格局；毛叶镰刀藓则在更新世就已形成与现代相近的分布格局。该研究确立了3种藓类植物的地理起源、地史分布及迁移路线。