新生代全球变化与中国古植物区系的演变

Global change in Cenozoic and evolution of flora in China

新生代是地质历史最年轻的一个时代 ,当时全球板块运动和岩浆活动强烈而频繁 ,中生代开始的大陆漂移活动继续进行 ,并于早第三纪末开始喜马拉雅运动 ,古地中海逐渐封闭 ,经过一系列的板块碰撞和洋底扩张 ,晚第三纪时地壳构造的基本轮廓和古地理面貌逐渐接近现代。受地壳运动的控制 ,全球新生代气候波动明显 ,早第三纪总体比较温暖 ,晚第三纪气候发生明显分异 ,气温显著下降 ,第三纪末期开始有冰川活动 ,一直持续到更新世末期 ,期间发生多次冰期和间冰期 ,全新世气候逐渐转暖。受上述全球变化的影响 ,我国新生代植物区系纵向演变和横向分异明显 ,早第三纪植物区系主要是纬向分带 ,从古新世到渐新世 ,我国植物区系主要分为北方区和南方区 ;晚第三纪初 ,由于喜马拉雅运动使青藏高原及东部的横断山脉地区持续抬升 ,逐渐形成独立的高原植物区。总体来说 ,晚第三纪植物区系和植被类型逐渐接近现代。第四纪由于青藏高原继续强烈抬升 ,激发了东亚季风 ,使我国的植物区系经向分带更加明显 ,植物区系和植被类型与现代已基本一致 ,到了全新世晚期 ,植物区系的演变除了受全球变化的影响外 。

Global plate movement and magma activities appeared frequently and dramatically in the Cenozoic Era,which is the youngest one in the river of geological history. Continents drifted ceaselessly at the beginning of the Mesozoic Era. Himalaya Mountain began to rise in the Early Tertiary Period. Meanwhile,the ancient Mediterranean was isolated gradually. After a series of plate collision and ocean bottom expansion,the fundamental outline of the earth’s crust structure and ancient landforms were formed and close to the shape of contemporary ones. Under the control of the Crust movement,global climate fluctuated significantly in the Cenozoic Era. It was relatively warm in the Early Tertiary Period,but the temperature decreased dramatically in the Late Tertiary Period due to distinct climate differentiation. Glacier activities also occurred at the end of the Tertiary Period,and continued till the end of the Pleistocene Epoch. Several Glacial and Interglacial Terms appeared alternatively from the Late Tertiary Period to the Late Pleistocene Epoch. Until in the Recent Epoch,global climate became to be warm again,gradually. Under the influence of the global climate changes mentioned above,the flora of China evolved progressively on both the direction of longitude and latitude in the Cenozoic Era. The Early Tertiary flora of China differentiated mainly along the latitudinal direction. Started from the Paleocene Epoch,the flora of China was divided into two types: North and South classes. The Qinghai Xizang Plateau in West China and Hengduan Mountain in East China elevated continuously due to Himalaya movement. Thus,the unique plateau flora was formed in the Late Tertiary Era. At the Quaternary Period,the Qinghai Xizang Plateau kept rising. It resulted in the formation of East Asia monsoon climate and the longitudinal differentiation of the flora of China. Consequently,the flora of China and vegetation types in the Quaternary Period became similar to modern flora and vegetation types. After the late Recent Epoch,the evolution of the flora of China was not only shaped by global climate changes,but also by the accelerating human activities.