川西与藏东南地区杜鹃花属植物及其分布的比较研究

Comparative study on Rhododendron and its distribution in W-Sichuan and SE-Tibet

通过青藏高原的川西地区与藏东南地区杜鹃花属植物类群及其数量、地理分布型与垂直分布格局的研究,借助比较生物学的研究方法,揭示这两个重要区域分布的杜鹃花属植物类群及其分布格局的异同。结果表明:青藏高原东部区域的川西地区杜鹃花属植物具有较原始类群多、较高分类等级多、大类群多并与我国东部和狭义横断山联系较广泛的区系特征,类群及其特有种的垂直分布重心较低;而青藏高原南缘区域的藏东南地区具有较进化类群多、较低分类等级多、小类群多、特化强烈并主要与狭义横断山有较密切联系的区系特征,类群及其特有种的垂直分布重心较高,且两地间近缘类群垂直替代现象明显。有关特征和现象与白垩纪晚期杜鹃花属起源地的温润气候、第三纪渐新世前后高原漫长的渐进抬升和第四纪高原的迅速隆升及其多次冰川的进退等三个地质历史节点和事件具有密切关联并相互对应。从而揭示了在共同的生物地质历史背景下,我国杜鹃花属植物地理区系及其垂直分布特征由东至西的趋异化过程与性质,并据此提出了在幅员广阔的中国—喜玛拉雅这个现代杜鹃花属植物分布中心内,可勾勒出三块具有明显分异的核心分布区,即川西—滇东北区、滇西北—滇西区、藏东南—藏南区。

Pattern of Rhododendron and its group quantity,geographical distribution type and vertical distribution were studied by the comparative biology between the both areas of W-Sichuan and SE-Tibet of Qinghai-Tibet plateau. The results showed that there were characteristics of Rhododendron for more original,large groups and high-class in taxology in W-Sichuan where there was a wider relationship between E-China and Mt. N-Hengduans,and a lower vertical distribution for the groups and endemic species. And the results also showed that there were those for much younger,smaller,endemic and low-class groups in SE-Tibet where there was a major relationship between Mt. N-Hengduans and a higher vertical distribution for them. Phenomena of the vertical substitution is obvious between the close groups of Rhododendron in both of the two areas. For the above characteristics and phenomena we can conclude these closely relation and correspond to three historical nodes and events about the warm-moist climate in the last Cretaceous Period,the gradual raise of Tibet Plateau in a long time before or after Oligocene in the Tertiary Period and the rapid raise of the plateau with the glacier happen in the Quaternary Period. Thereby it is opened out that the course and characters dissimilate in the flora and their vertical distribution of Rhododendron from the east to the west China under the common background of the bio-geology. And base on it,three different core areas can be drawn,W-Sichuan-NE-Yunnan,NW-W-Yunnan and SE-S-Tibet in the modern distribution center of Rhododendron in the wide Sino-Himalaya flora region.