Coal forests were the vast swathes of

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

s that covered much of the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

land areas during the late Carboniferous (

Pennsylvanian Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology) The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, in the International Commission on Stratigraphy, ICS geologic timesca ...

) and

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...

times.Cleal, C. J. & Thomas, B. A. (2005). "Palaeozoic tropical rainforests and their effect on global climates: is the past the key to the present?" ''Geobiology'', ''3'', p. 13-31. As vegetable matter from these forests decayed, enormous deposits of

peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...

accumulated, which later changed into

coal Coal is a combustible black or brownish-black sedimentary rock, formed as stratum, rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen ...

. Much of the

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...

in the peat deposits produced by coal forests came from photosynthetic splitting of existing

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

, which released the accompanying split-off oxygen into the atmosphere. This process may have greatly increased the oxygen level, possibly as high as about 35%, making the air more easily breathable by animals with inefficient respiratory systems, as indicated by the size of '' Meganeura'' compared to modern dragonflies. Coal forests covered tropical

Euramerica Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around (Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...

(Europe, eastern North America, northwesternmost Africa) and Cathaysia (mainly China). Climate change devastated these tropical rainforests during the Carboniferous period. The Carboniferous Rainforest Collapse was caused by a cooler drier climate that initially fragmented, then collapsed the rainforest ecosystem. During most of the rest of Carboniferous times, the coal forests were mainly restricted to refugia in North America (such as the

Appalachia Appalachia () is a cultural region in the Eastern United States that stretches from the Southern Tier of New York State to northern Alabama and Georgia. While the Appalachian Mountains stretch from Belle Isle in Newfoundland and Labrador, ...

n and

Illinois Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Roc ...

coal basins) and central Europe. At the very end of the Carboniferous period, the coal forests underwent a resurgence, expanding mainly in eastern Asia, notably China; they never recovered fully in Euramerica. The Chinese coal forests continued to flourish well into Permian times. This resurgence of the coal forests in very late Carboniferous times seems to have coincided with a lowering of global temperatures and a return of extensive polar ice in southern

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final st ...

, perhaps due to lessening of the

greenhouse effect The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ...

as the massive coal deposition process extracted

from the atmosphere.

Environment

The coal forests seem to have been areas of flat, low-lying swampy areas with rivers flowing through from higher, drier land. When the rivers flooded, silt gradually built up into natural

levee A levee (), dike (American English), dyke (Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually earthen and that often runs parallel to the course of a river in its floodplain or along low-lying coastl ...

s. Lakes formed as some areas subsided, while formerly wet areas became dry from silt buildups. When a forested area became dry enough to be set on fire by lightning, the resulting forest fire left charcoal, the fusain component of coal.

Plant life

There seems to have been a rich and varied flora, with sets of species for each type of growing condition. The most varied flora seems to have been leave vegetation, with many species of trees, bushes, creepers, etc. Thickets of ''

Calamites ''Calamites'' is a genus of extinct arborescent (tree-like) horsetails to which the modern horsetails (genus '' Equisetum'') are closely related. Unlike their herbaceous modern cousins, these plants were medium-sized trees, growing to heights of ...

'' seem to have favored the edges of lakes and waterways.

Lycopsid Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching s ...

genera specialized in various roles: ''Paralycopodites'' as a pioneer on newly silted lakes shallow enough for land vegetation to start; ''Diaphorodendron'' later when the ground had become

y. Other species specialized in re-settling land which had been briefly deforested by flooding: ''Synchysidendron'' and ''Lepidodendron'' in mineral-soil areas and ''Lepidophloios'' in peat areas. ''Cordaites'' may have favored drier areas of the swamp. One author thinks that '' Sigillaria'' favored the intermediate areas between levee habitat and swamp habitat. In the later part of this period tree ferns tended to take over from lycopsid trees. Some of the characteristic plants of the coal forests were: *'' Sigillaria'' *''

Lepidodendron ''Lepidodendron'' is an extinct genus of primitive vascular plants belonging to the family Lepidodendraceae, part of a group of Lycopodiopsida known as scale trees or arborescent lycophytes, related to quillworts and lycopsids (club mosses). T ...

'' *''

'' * pteridosperms

British coal forest fossils

Genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial ...

recorded in Great Britain include: * Pteridosperm leaves: Alethopteris, Callipteridium, Cyclopteris (leaf bases), ?Desmopteris, Dicksonites, Eusphenopteris, Fortopteris, Hymenophyllites, Karinopteris, Laveinopteris, Linopteris, Lonchopteris, Lyginopteris, Macroneuropteris, Margaritopteris, Mariopteris, Neuralethopteris,

Neuropteris ''Neuropteris'' is an extinct seed fern that existed in the Carboniferous period, known only from fossils. Major species include ''Neuropteris loschi''. See also *Coal forest *''Macroneuropteris ''Macroneuropteris'' is a genus of Carbonifer ...

, Odontopteris, Palmatopteris, Paropteris, Reticulopteris *Pteridosperm spore organs: Aulacotheca (male), Boulaya, Potoniea (male), Whittleseya (male) *Pteridosperm seeds: Gnetopsis, Hexagonocarpus, Holcospermum, Lagenospermum, ?Polypterocarpus, Rhabdocarpus, Trigonocarpus *Fern fronds: Aphlebia, Bertrandia, Corynepteris, Crossotheca, Cyathocarpus, Lobatopheris, Oligocarpia, Pecopteris, Polymorphopteris, Renaultia, Sphyropteris, Sturia, Zeilleria * Tree-fern leaves: Caulopteris *Tree-fern stems: Artisophyton, Megaphyton *

tree stems and leafy shoots: Cyperites,

, Ulodendron *Lycopsid tree stems: Asolanus, Bothrodendron, Cyclostigma, Lepidophloios, Sigillaria, Sublepidophloios, Syringodendron (de-barked) *Lycopsid reproductive parts: Flemingites, Lepidodostrobus, Lepidodostrobophyllum (sporophylls), Sigillariostrobus *Lycopsid (herbaceous) stems: Lycopodites, Selaginellites * Sphenopsid leaves:

Annularia ''Annularia'' is a form taxon, applied to fossil foliage belonging to extinct plants of the genus ''Calamites'' in the order Equisetales. Description ''Annularia'' is a form taxon name given to leaves of ''Calamites''. In that species, the leav ...

, Asterophyllites *Sphenopsid stems:

*Sphenopsid reproductive parts: Bowmanites, Calamostachys, Macrostachya, Palaeostachya * Cordaite leaves: Cordaites *Cordaite stem pith case: Artisia (pith cast) *Cordaite seeds: Cordaicarpus *Cordaite cones and seeds: Cordaitanthus *May be

progymnosperm The progymnosperms are an extinct group of woody, spore-bearing plants that is presumed to have evolved from the trimerophytes, and eventually gave rise to the gymnosperms, ancestral to acrogymnosperms and angiosperms (flowering plants). They ...

: leaves: Noeggerathia *

Conifer Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ex ...

leaves: Walchia *Seeds: Carpolithus, Cornucarpus, Samaropsis

Palaeontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

s have described many species for some of these genera, e.g. (in Britain): ''Sigillaria'' 33, ''Lepidodendron'' 19, ''Alethopteris'' (pteridosperm leaves) 11, ''

'' 8. Some easily identified species occur over a wide area but only for a small part of the coal-forming period, and are thus useful as

zone fossil Index fossils (also known as guide fossils or indicator fossils) are fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, ...

Animal life

Animals inhabiting the coal forests were

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s (particularly insects),

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% ...

, labyrinthodont amphibians, and early reptiles. An example of plant-eating was evidenced by tree

lycopsid Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching s ...

tracheids found in an '' Arthropleura'''s gut. Amphibians were widespread, but once the coal forests fragmented, the new environment was better suited to reptiles, which became more diverse and even varied their diet in the rapidly changing environment.

References

External links to reconstruction images of coal forest

Coal forest.
Department of Earth and Environmental Sciences, The Open University. Retrieved January 6, 2012.

Burpee Museum of Natural History (March 2000). Retrieved January 6, 2012. *{{cite web, url=http://www.ucmp.berkeley.edu/carboniferous/carboniferous.php, title=The Carboniferous Period, work=Geologic time scale, publisher=University of California Museum of Paleontology, accessdate=January 6, 2012
Image from Das Rektorat der WWU Münster.
Westfalische Wilhelms-Universitat Munster. Retrieved January 6, 2012. Carboniferous paleogeography Carboniferous life