晚古生代瓢叶目植物的古生态学探讨

NOTES ON THE PALAEOECOLOGY OF LATE PALAEOZOIC NOEGGERATHIALES

对已知瓢叶目植物生态信息较为全面的观察分析表明 ,华夏植物群中瓢叶目植物的生态条件与欧美植物群较为相似。很可能 ,瓢叶目植物在欧美植物区和华夏植物区均可发育于水分充足的低地植物群和排水条件较好的高地植物群。对华夏植物群中某些低地群落的植物古生态样方统计分析结果显示 :一般情况下 ,瓢叶目植物的属种数量与植物群落中其它类群数量相比所占份额较少 (分异度不高 ) ,而它的个别种的数量则在群落中占据的比重较大 ,甚至占据优势地位 (丰度较高 )。从群落结构来看 ,瓢叶目植物所在的群落往往具有较好的分层结构。瓢叶目和某些楔叶纲、真蕨和种子蕨纲植物共同构成群落的林下层植被。群落的中、高层通常是石松纲和科达纲 。

A comprehensive analysis on the palaeoecology of Noeggerathiales indicates that the ecological condition of this group of plants from Cathaysian and Euramerican floras may be similar. It is very possible that Noeggerathiales from both Cathaysian and Euramerican floras could live in wet lower land or arid upland. Palaeoecological sample statistics on certain lower land Cathaysian floras containing noeggerathialean plants indicates that generally in a community, the quantity of genera and species (diversification) of noeggerathialean plants is relatively very limited. However, the number of a particular species (abundance) is usually very high, sometimes even taking the predominant position in the community. As far as the structure of the community is concerned, the community usually has well defined forest layers. Noeggerathiales together with some shenophyllaleans, ferns and seed ferns comprise the understory of a forest. The middle and upper layers may be composed of Lepidodendron, Cordaites, Calamites and some tree ferns or seed ferns.