摘要
本文根据古植物学资料及与现代植物区系的对比分析来研究植物区系的演变和来源，文中论述了自白垩纪以来各时期华北植物区系的演变发展过程，认为华北现代种子植物区系有４个来源，即主要是本地起源和演化发展的，其他来自中国西南和南方亚热带—热带地区，中亚一地中海区和欧亚草原，东北亚和西伯利亚温—寒地区。
The flora of North China (excluding Qingling Mts.) includes about 151 families, 914 genera, and 3 925 species of seed plants. A comparison of paleobotanical material and present day flora provided information on their evolution and sources. The evolution of North China's flora and vegetation since the Cretaceous may be divided into the following five periods: 1. In the Early Cretaceous, floras were dominated by ferns and gymnosperms comprised mainly of Lygodiaceae, Ephedraceae, Cycadaceae, Ginkgoaceae and the genus Brachyphyllum of coniferae, etc. A few of the angiosperms that appeared initially are Tricolpollenites, Quercoitites type of family Fagaceae and Salixpollenites of family Saliaceae, etc. The vegetation was arid tropical subtropical in aspect. 2. During the Late Cretaceous, angiosperms increased greatly, becoming about equal in number to ferns and gymnosperms. They are mainly composed of Exesipollenites, Gothanipollis, Plicapollis , etc. and formed a subtropical mixed forest and scrub vegetation. 3. In the Paleogene, floras were dominated by angiosperms and hydroherbs such as Potamogeton . The earlier ferns and gymnosperms were greatly depleted or became extinct. However, the coniferae developed including the families Pinaceae, Taxodiaceae, and the genus Podocarpus . The vegetation was a subtropical forest landscape. 4. In the Neogene, angiosperms increasingly flourished with a great number of Amentiferae, temperate elements, and herbs. The differentiation between the northern and southern parts of North China became obvious. The vegetation is a warm temperate mixed needle and broad leaved forest and deciduous broad leaved forest in the north, and a warm temperate subtropical evergreen broad leaved forest in the south. The xerophilous deciduous broad leaved forest and steppe appeared in the late Neogene. By then, the present flora and vegetation were basically formed. 5. In the Quaternary, climatic fluctuations induced plants to migrate and reassemble resulting in warm temperate forest and open forest steppe alternating during glacial and interglacial periods and in the increase in herbs and the expansion of steppe. After the late glacial, the flora and vegetation were similar to that of the present because of a warming climate. The sources of the present flora of north China may be recognized as taking four paths. It is mainly of autochthonous origin with evolution from the Paleogene to the present like various ancient woodplants, temperate and subtropical or tropical elements. Herbs occurred mostly since the Neogene. Besides, many species are from subtropical tropical regions of southwest and south China, especially from Henduan Mts. Some are from the Central Asia Mediterranean and Europe Asia steppe as well as northeast Asia and the Siberian temperate cold area due to the expansion of steppe as the climate became cold during the Neogene and the Pleistocene.
出处
《地理学报》
EI
CSCD
北大核心
1999年第3期213-223,共11页
Acta Geographica Sinica
关键词
植物区系
演变
来源
华北地区
flora, change, source, North China floristic region
