Karbonské tropické pralesy

Carboniferous tropical forests by Stanislav Opluštil.

The onset of the Late Paleozoic Ice Age at the begining of late Carboniferous (Pennsylvanian) times about 319 My ago resulted in the growth of glaciers coupled with an eustatic fall in sea-levels of about 100 m. The resulting emergence of vast areas of continental shelf previously occupied by shallow seas expanded the areas of coastal lowlands, and those around the equator were soon covered by tropical forests. For the first time in earth history, tropical forests spread across an area of similar size to the present-day tropical rain forests. In contrast to the modern-day tropical forests, the Pennsylvanian tropical forests were dominated by primitive spore-producing pteridophytes, accompanied by several and now extinct groups of early seed plants such as pteridosperms and cordaites. A typical part of this tropical vegetation was the peat-forming wetland forests commonly refered to as the Coal Measure Forests, dominated in early to middle Pennsylvanian times by giant and bizzare arborescent lycopods (Lepidodendron, Lepidophloios, Sigillaria), replaced by tree ferns (Psaronius) in Late Pennsylvanian times.

After flourishing for about 12 My, this ecosystem started to collapse at the start of Late Pennsylvanian times due to aridisation of the climate and locally also tectonic proceses. By the end of Pennsylvanian times, about 300 My ago this, tropical forest completely diasappeared from western and central Pangea (an area now forming a central parts of North America and Europe), although it continued to flourish in eastern Pangea (now eastern China) until well into Permian times.

The reconstruction of these spectacular early tropical forests, including the habits of the extinct plants, is based on fragmentary and drifted fossil remains, and is very complicated. The best data are provided by sites where vegetation was buried in growth position by volcanic ash, which preserved the structure and composition of the forest. Such localities are, unfortunately, very rare. However, there are a number of such sites in western Bohemia, Czech Republic, where investigations have revealed the existence of several types of peat-forming forests, ranging from low-diversity assemblages composed of about five or six shrubby species, to diverse forest dominated by tree lycopods.