Tiering on Land – Trees and Forests (Late Palaeozoic)

Abstract The first regional‐scale forests appeared in mid‐Carboniferous times, c . 325 million years ago (Ma). Known as the coal swamps, they extended over large parts of tropical Pangaea and lasted for about 40 million years. The dominant plants of the swamps were arborescent lycopsids, sphenopsids, ferns, pteridosperms and cordaitanthales. Many were very fast‐growing plants and resulted in thick peat deposits being formed, which have subsequently changed into economically important coals. Changes in the geographical extent of these tropical swamps correlated with the waxing and waning of the Late Palaeozoic Ice Age polar ice sheet, and the carbon sequestration caused by the swamps may have been affecting global climates. The development of the swamps coincided with a major global diversification in insects and may also have been home to some early terrestrial amphibians and reptiles. Key Concepts The coal swamps were the first regional‐scale forests to occur on Earth. The swamps occupied a broad belt of land in palaeotropical Pangaea during the late Carboniferous and early Permian (325–275 Ma). They were responsible for one of the highest rates of terrestrial carbon sequestration in Earth history. The size of the coal swamps was correlated with climate fluctuations during the Late Palaeozoic Ice Age. Insects and possibly of tetrapod vertebrates diversified during the time of the coal swamps.