华东天目山脉、黄山山脉、大别山脉竹类植物区系分析,兼论区系的起源与扩散

华东天目山脉、黄山山脉、大别山脉竹类植物较为丰富,分别有10属/75种(含种下等级)、8/49、7/30.通过对属、种的分布型分析,前二者竹类植物区系属于典型的华东区系,起源的时间不迟于早第三纪的始新世;而大别山脉虽仍属华东区系的范畴,因渗入了不少华中区系的成分,已具有某些经向过渡性特征,且起源的时间较晚.这3个山脉的竹类植物区系均具有显著的亚热带性质.天目山脉不仅是刚竹属Phyllostachys和短穗竹属Brachystachyum的分化变异中心,也极有可能就是它们的起源中心,但它们自此地起源后的散布方式有所不同,刚竹属在我国亚热带为四周放射状顺序渐进,扩散的范围颇广;短穗竹属存在东西南北4条散布路线,但向各方扩散的距离相差甚远.这些山脉与华东其他地区竹类植物区系联系密切,与华中竹类植物区系也有一定的联系,但与华南、西南等地竹类植物区系联系微弱.从地理位置和区系组成来看,黄山山脉的竹类植物区系来源于天目山脉,大别山脉的竹类植物区系又来源于黄山山脉,前者都是在后者扩展的基础上融合了其他区系的一些成分后发展而成,大别山脉又是北方秦岭以东广大丘陵平原地区竹类植物区系的发祥地.

Analysis of Bamboo Floras in Tianmushan, Huangshan and Dabieshan Mountains in East China, with Special Reference to Their Origin and Dispersal

Three bamboo floras of East China were investigated in Tianmushan Mountains (on the border between Zhejiang and Anhui Provinces), Huangshan Mountains (in the south of Anhui), and Dabieshan Mountains (in the border area of Henan, Hubei and Anhui Provinces), which include 10 genera with 75 species, 8 genera 49 species, and 7 genera 30 species, respectively. Areal type analysis of genus and species elements indicates that the bamboo floras in three mountains are markedly subtropical in nature and can be recognized as important part of bamboo flora of East China, however, the flora of Dabieshan Mountains reveals a transitional character having certain amount of elements of Central China. Based on a priliminary inference made from geologic history, modern distribution pattern of bamboos and principle of historical phytogeography, the bamboo floras of Tianmushan Mountains and Huangshan Mountains originated not later than the Eocene epoch of the Paleogene period, and earlier than that for Dabieshan Mountains. Most of the species of genera Phyllostachys and Brachystachyum, with primitive taxa, have been found in Tianmushan Mountains where geochronology is quite age-old and relatively stable in geological structure, which shows the mountains can be considered as differentiation centre and possible origin centre of these two genera. Phyllostachys extended it distribution area radially from the origin center to subtropical China, while Brachystachyum had four distribution routes: the east route ran to E and SE Zhejiang, the south to the eastern part of Nanling Mountains, the west to Jiangxi, and the north to E Anhui. The relationships among the three bamboo floras are discussed.