广西地质、地理和植物区系起源与发展

THE PALEGEOLOGY,PALEGEOGRAPHY AND DEVELOPMENT OF FLORA IN GUANGXI AREA

广西地质发展史约从８亿年前的晚元古代开始，当时仅有海生的藻类植物区系繁衍于广西深海——半深海海域中．陆地植被的兴起已到了志留纪末（约５亿年前），出现于云开大山，西大明山——大瑶山隆起的近海湿润地区，主要植被是由北面江南古陆和西部康滇古陆南移入侵的各种裸蕨类植物．志留纪末至泥盆纪时，广西结束了地槽沉积的历史，大部分地区成为陆地，这时华北古陆植被成分如节蕨、石松、真蕨等组成的蕨类森林已分布到广西境内．到晚古生代末期（石炭、二叠纪），广西植被以较为进化的孢子植物（如真蕨类）为主，在此时期也孕育了前裸子植物的原始分子．广西中生代植被及植物区系成分早期以蕨类和裸子植物为主；中期以裸子植物为主；晚期（侏罗纪至白垩纪初）则开始出现较多的被子植物．在整个古生代和中生代的植被演化过程中，广西植物区系始终与华夏植物区系保持着密切的联系．广西现代地形特征基础是在中生代末至新生代初（距今约０．６５亿年）的一系列地壳运动后奠定的，到新生代晚期在广西（特别是桂南一带）已经形成了以樟科、壳斗科、胡桃科、芸香科、大戟科、棕榈科等为优势的热带——亚热带植物区系景观．广西现代植被及植物区系的雏形是在第四纪经历了气候环境的干湿交替变化及冷暖（冰?

There has been about 8 billion years since the Flora existed in Guangxi Autonomous Region when the unicell alga ( Trematospharium etc.) lived in deep semideep sea in south China. The continental Flora origined in the end of the silurian(about 5 billion years ago), it was discovered in moisture area of the Yunkai Moutain and the Westdamin dayiao Moutain,which located in the near sea. The vegetable elements is the various Psilophytes migrating fromJiangnan Landmass(northern) and Kangdian Landmass(western). From the end of Silurian tothe Devornian,ended the maring deposit,the most of Guangxi rise to land and the Pteridium forest living in North China had distributed to Guangxi. In the end of later Palaeozoic (Carboniferous and Permian), the floristic elements were the more evolutionary sporal plants(e.g. Archaeopteris) and the Pteridospermae(e.g. Cathaysiopteris), Spermatophytes(e.g. Ginkgophyllum and Ullmannia). The orginal elements of the “Pre angiosperm” would be origined from this Spermatophytes. In the early Mesozoic, the vegetable and Flora in Guangxi was the Pterids and Gymnophytes,in middle Mesozoic the Gymnophytes, and in late jurassic and upper cretaceous, appeared more angiospermae. It was about 65 million years ago in the end of the Mesozoic and the beginning of Phanerozoic, the mordern topographyic characters in Guangxi has been built in a series of the crustal movement. In the late Phanerozoic, the major component of Flora in South Guangxi has formed by Louraceae,Fagaceae,Juglandaceae,Rutaceae,Euphorbiaceae,Palame etc., which made the embryonic landscape of Guangxi Flora.