---

作 者 ：田宝霖 王士俊 李承森 陈贵仁

期 刊 ：植物学通报 2000年 17卷 专辑期 页码：21-33

关键词：华夏植物群；起源中心；演化中心；迁移；绝灭率；演化；

摘 要 ：讨论了华夏植物群的起源中心和演化中心，发现了华夏植物群各时期的不同演化中心及其移动路线，对华夏植物群的起源及演化机制通过对鳞木类及科达植物解剖构造的分析，提出华夏植物群的起源与演化的机制是植物界在当时对环境的适应中的随机优势不同和地理隔绝独立演化发展而形成。对华夏植物群各时期的属、种数，新增种数，新增百分率，绝灭种数和绝灭百分率等进行了统计，提出来华夏植物群在其存在的88 Ma时间中，共发生了8次绝灭事件，平均每11 Ma发生一次。多数具有周期性，其中，有4次绝灭率较小，为正常的绝灭beckground extinction,有两次较大绝灭，其绝灾率为50％—60％，反映了华夏植物群在发展、演化中的较大的更新、更替。晚二叠世早、晚期之间华夏植物群发生衰退事 件，是一个非周期性绝灭事件，可能与古气候转干旱有关。华南区、华北区还有所不同，其绝灭率分别达到62％—90％。华夏植物群在二叠纪末绝灭。对于华夏植物群的绝灭机制认为是华夏植物群在晚二叠世晚期尤其是接近二叠纪末，已经衰退至对环境变化适应无力阶段，加上火山作用等地球本身事件和可能有地外突发事件的发生，触动和促发了其最后的绝灭。

Abstract:This paper discusses the origin center and the evolution center of the Cathaysian Flora. The authors discover that there are different evolution centers in different geological ages in China, and discuss their moving line through different geological ages. By analysing the anatomic stmcture of the fossil plants of Lycopods and Cordaitales, the authors suggest that the main mechanics of the origination and the evoluion of Cathaysian Flora is the result of the different tochastic dominances in adaptation to the external environments and the geographical separation and isolately developing from the Euramerican Flora. In this paper, the authors also make some works on statistics by counting up the number of the genus, species, extincted species, newly increased species, the percentage ratio of the newly increased species in different geological ages and discover that the Cathaysian Flora happened 8 time extinction events during its exisfing period in Carboniferous and Permian (88 Ma). In average, there happened 1 time extinction event per 11 Ma. Most of the extinction events happened periodically. Among them, 4 extinction events with smaller extinctional percentage ratio,can be called as normal extinction or background extinction, their extinction percentage ratio only reached up to 10.3% -16.2%. 2 of the 8 extinction events were larger, their percentage ratio of extinction reached up to 50%-60%, that refleeted the larger renewal and replacement of the composition of Cathaysian Flora. The rest 2 events happened at the boundary line of late and early Permian and at the end of Pemaian were serious. The former is a nonperiodical extinction event that might be related to the climate into arid changing in the world. In South China and in North China the percentage ratio of extinction reached up to 62% and 90% separately. Cathaysian Flora extincted totally at the end of Permian. As to the mechanics of the total extinction of Cathaysian Flora, the authors suggest that the Cathaysian Flora had become into a powerless stage before the big evironment changing happened in the late Late Permian, especially at the end of Permian. Besides, there happened series of the terrestrial events, such as, at the turn of Permian-Triassic period widely distributed the volcanic activities, and it is very possible that there abruptly happened an extraterrestrial event, certain celestrial bodies collided the earth accidently that stirred up and improved the total extinction of Cathayrion Flora.

---