古地中海植物区系在青藏高原隆起后的演变和发展

青藏高原植物区系是第三纪古地中海退却,青藏高原成陆以后开始发展演变而来的。化石资料表明,在早第三纪时青藏高原具有同特提斯早第三纪喜暖的樟叶林一致的植物区系;在第三纪中期以后由于古地中海气候逐步旱化而逐步消失;在横断山及喜马拉雅和东亚其它地区得以保存和发展。新第三纪以后由于古地中海气候变得干旱,原暖湿植物区系逐步被现代旱生的地中海植物区系所取代。一些代表类群：黄花木属、沙冬青属、Anagyris、钩毛草属、无心菜属、铁筷子属,绿绒蒿属,芒苞草科,马桑属、高山栎组、沙棘属等类群分布区和地理分布格局的形成,说明了这些旱生的地中海成分随着青藏高原的隆升进一步分化形成了中亚成分、地中海-西亚-中亚成分、旧世界温带成分、北温带成分、中国喜马拉雅成分等,并形成了一些间断、残遗和特有的分布现象。因此,古地中海植物区系是现代青藏高原植物区系的一个重要源头。通过分析也进一步论证了第三纪早期沿古地中海东西迁移路线和在此路线分别同热带亚洲、非洲和南美洲进行的南北迁移可能是青藏高原同欧洲、北美、南半球等间断分布格局形成的一条重要途径。

QINGHAI-TIBET PLATEAU UPLIFT AND ITS IMPACT ON TETHYS FLORA

The flora of Qinghai-Tibet Plateau started in late Cretaceous or early Tertiary. Paleobotanical data had showed that there were same or similar flora in Qinghai-Tibet Plateau to Tethyan Tertiary evergreen flora in that time. Along with the gradual climate change of the Tethys, which  had become aridity since Neogene, the evergreen flora was gradually replaced by semiarid or arid flora of the Tethys and only preserved and developed in E Asian and Indo-Malaya. Analysis of some representative groups:Piptanthus, Ammopiptanthus, Anagyris, Arenaria, Kelloggia, Coriaria, Hippophae, Velloziaceae, Meconopsis, Helleborus and sclerophyllus oaks in Qinghai-Tibet Plateau, showed that the uplift of the Qinghai-Tibet Plateau caused the semiarid or arid flora of Tethys evolved to adapt to different environment and differentiated into different elements,i.e. C Asian, Mediterranean-W Asian and C Asian, the temperate of Old World, North Temperate and Sino-Himalayas and others, as well as some disjunction, endemic and relic distribution. Furthermore, the analysis also demonstrated the dispersal pathway of Tethys flora along Tethys to and from east and west, and to from north and south, to Tropical Asia, Africa and South America in early tertiary, which was one of the main reasons causing modern disjunction between Qinghai-Tibet Plateau and Old World Temperate, as well as W America, Africa, S America and tropical Asia.