Pennsylvanian uplands were forested by giant cordaitalean trees

doi:10.1130/G20371.1

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Pennsylvanian uplands were forested by giant cordaitalean trees

Journal Article•DOI•

Pennsylvanian uplands were forested by giant cordaitalean trees

Howard J. Falcon-Lang¹, Arden R. Bashforth²•Institutions (2)

University of Bristol¹, Memorial University of Newfoundland²

01 May 2004-Geology (Geological Society of America)-Vol. 32, Iss: 5, pp 417-420

TL;DR: The discovery of a new Pennsylvanian (Bolsovian) plant assemblage in southwest Newfoundland confirms this hypothesis and allows the architecture of these upland trees to be reconstructed in detail.

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Abstract: The precise timing of when upland terrains first became forested is highly controversial. Pennsylvanian palynoflora and megaflora transported into marine highstand deposits imply that emergent topographic highs may have supported cordaitalean forests. The discovery of a new Pennsylvanian (Bolsovian) plant assemblage in southwest Newfoundland confirms this hypothesis and allows the architecture of these upland trees to be reconstructed in detail. The assemblage includes several hundred calcareously permineralized stumps, trunks, and branches, and represents the remains of shallowly rooted cordaitalean trees that were ≤48.5 m high when mature. The fossils occur in alluvial conglomerates that constitute a 10-km-diameter outlier on the margins of the paleoequatorial Variscan foreland. The paleogeographic setting together with plant taphonomic inferences strongly indicate that these giant trees were transported from nearby upland alluvial plains and deposited in an elevated intermontane basin. This interpretation is supported by analysis of rootstock morphology, which implies tree growth in thin soils consistent with an alluvial gravel substrate. This improved understanding of Pennsylvanian upland forests has important implications for geochemical modeling of the global carbon cycle.

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Journal Article•DOI•

Palaeozoic tropical rainforests and their effect on global climates: is the past the key to the present?

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Christopher J. Cleal¹, Barry A. Thomas²•Institutions (2)

Cardiff University¹, Aberystwyth University²

01 Jan 2005-Geobiology

TL;DR: Wetland forests, known as coal forests, extended over large areas of the palaeotropics during the Late Carboniferous and the Permian Periods as discussed by the authors.

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Abstract: Wetland forests, known as coal forests, extended over large areas of the palaeotropics during the Late Carboniferous and the Permian Periods. They were initiated during the Serpukhovian Age as a response to lowering sea levels having exposed large areas of continental shelf. They expanded dramatically during the late Bashkirian Age, but then contracted by over one-half during the Kasimovian Age. The estimated loss of carbon sink probably resulted in an annual increase in atmospheric CO2 of about 2–5 ppm, and coincided with clear evidence of global warming in both the northern and southern high latitudes. A return to cooler conditions in very Early Permian times coincided with an expansion of the palaeotropical coal forests in the Far East, but this was short-lived and most of the rest of the Permian was a time of global warming. The Palaeozoic evidence clearly confirms that there is a correlation between levels of atmospheric CO2 and global climates. However, care must be taken in extrapolating this evidence to the present-day tropical forests, which do not act as a comparable unsaturated carbon sink.

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171 citations

Cites background from "Pennsylvanian uplands were forested..."

...The muddy lake-margins supported swards of sphenophytes adapted to the unstable substrates (Gastaldo, 1992; Pfefferkorn et al ., 2001), whereas cordaite forests grew on the drier habitats on the margins of the forests (Falcon-Lang, 2003a; Falcon-Lang & Bashforth, 2004)....
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Journal Article•DOI•

Wetland-Dryland Vegetational Dynamics in the Pennsylvanian Ice Age Tropics

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William A. DiMichele

01 Feb 2014-International Journal of Plant Sciences

TL;DR: Lower-diversity worlds such as the late Paleozoic, with a rich spectrum of environmental variations, offer insights into relationships between organisms and environments that expand understanding of these phenomena and enlarge their sense of what is possible or probable as the authors look to the future.

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Abstract: Premise of research. The Late Paleozoic Ice Age was the last extensive pre-Pleistocene ice age. It includes many climate changes of different intensities, permitting examination of many and varied biotic responses. The tropical Pennsylvanian Subperiod, usually visualized as one vast wetland coal forest, in fact also was dominated, periodically, by seasonally dry vegetation that, in turn, covered most of the central and western Pangean supercontinent. Equatorial wetland and dryland biomes oscillated during single glacial-interglacial cycles. This recognition changes understanding of the Coal Age tropics; examination of their spatiotemporal patterns indicates that these vegetation types responded differently to global environmental disturbances and long-term trends and points to potentially different underlying controls on evolutionary histories of their component lineages.Methodology. This study is based on the published literature and on examination of geological exposures and fossil floras, mainly from N...

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147 citations

Cites background from "Pennsylvanian uplands were forested..."

...10A, 10B), from scrambling forms (Rothwell and Warner 1984), to small trees (Cridland 1964), to large, woody trees of tall stature (Falcon-Lang and Scott 2000; Falcon-Lang and Bashforth 2004, 2005; Šimůnek et al. 2009; Césari and Hünicken 2013)....
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...10A), ranging upward of 50 m in height (Falcon-Lang and Scott 2000; Falcon-Lang and Bashforth 2004)....
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...In the Early and early Middle Pennsylvanian, such areas, dominated by cordaitaleans, are documented mainly in Atlantic Canada in central Pangea (Falcon-Lang and Scott 2000; Falcon-Lang 2003b, 2006; Falcon-Lang and Bashforth 2004; Dimitrova et al. 2011; Bashforth et al. 2014)....
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Journal Article•DOI•

Cyclic changes in Pennsylvanian paleoclimate and effects on floristic dynamics in tropical Pangaea

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William A. DiMichele¹, C. Blaine Cecil², C. Blaine Cecil¹, Isabel P. Montañez³, Howard J. Falcon-Lang⁴ - Show less +1 more•Institutions (4)

National Museum of Natural History¹, United States Geological Survey², University of California, Davis³, Royal Holloway, University of London⁴

01 Aug 2010-International Journal of Coal Geology

TL;DR: Wetland floras narrowly define perceptions of Pennsylvanian tropical ecosystems, the so-called coal Age as discussed by the authors, and the importance of seasonally-dry vegetation has suffered from conceptual and terminological confusion.

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138 citations

Cites background or result from "Pennsylvanian uplands were forested..."

...Chaloner (1958) coined the term “Neves effect” to explain the occurrence of cordiatalean pollen in marine sediments, suggesting that rising sea level brought plants of higher elevation, better-drained areas into proximity of marine environments during transgressions (Falcon-Lang, 2004b)....
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...Paleosols also document a range of climatic conditions from those where rainfall exceeded evaporation to conditions of rainfall seasonality (Besly and Fielding, 1989; Falcon-Lang, 2004b; Driese and Ober, 2005)....
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...The coal beds in east-central Pangaea (western Europe) through to the Tethyan border regions, suggest that the latitudinal climate gradient was at a continental scale....
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...Not all such basins were open to the sea, such as the Variscan orogenic basins of central Europe (e.g., Opluštil and Cleal, 2007), but they were nonetheless of low enough elevation during aggradation, probably near sea level, to avoid subsequent erosional obliteration....
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...Many of these basins are part of the Variscan Foreland Complex, which stretched from eastern Europe through eastern North America (Rast, 1984; Calder, 1998; Falcon-Lang et al., 2004, 2006; Opluštil and Cleal, 2007)....
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Journal Article•DOI•

Pennsylvanian tropical rain forests responded to glacial-interglacial rhythms

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Howard J. Falcon-Lang¹•Institutions (1)

University of Bristol¹

01 Aug 2004-Geology

TL;DR: In this paper, a sequence-stratigraphic analysis of megafloral and palynofloral assemblages within the Westphalian D-Cantabrian Sydney Mines Formation of eastern Canada is presented.

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Abstract: Pennsylvanian tropical rain forests flourished during an icehouse climate mode. Although it is well established that Milankovitch-band glacial-interglacial rhythms caused marked synchronous changes in Pennsylvanian tropical climate and sea level, little is known of vegetation response to orbital forcing. This knowledge gap has now been addressed through sequence- stratigraphic analysis of megafloral and palynofloral assemblages within the Westphalian D–Cantabrian Sydney Mines Formation of eastern Canada. This succession was deposited in a low- accommodation setting where sequences can be attributed confidently to glacio-eustasy. Results show that long-lived, low-diversity peat mires dominated by lycopsids were initiated during deglaciation events, but were mostly drowned by rising sea level at maximum interglacial conditions. Only upland coniferopsid forests survived flooding without significant disturbance. Mid- to late interglacial phases witnessed delta-plain progradation and establishment of high-diversity, mineral-substrate rain forests containing lycopsids, sphenopsids, pteridosperms, cordaites, and tree ferns. Renewed glaciation resulted in sea-level fall, paleovalley incision, and the onset of climatic aridity. Glacial vegetation was dominated by cordaites, pteridosperms, and tree ferns; hydrophilic lycopsids and sphenopsids survived in paleovalley refugia. Findings clearly demonstrate the dynamic nature of Pennsylvanian tropical ecosystems and are timely given current debates about the impact of Quaternary glacial-interglacial rhythms on the biogeography of tropical rain forest.

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124 citations

Cites background from "Pennsylvanian uplands were forested..."

...…with Pennsylvanian maximum flooding surfaces across Euramerica (Davies and McLean, 1996; Falcon-Lang, 2003a) and may record a distal signature from cordaite-conifer– dominated upland floras that survived the deglaciation-driven flooding of lowland environments (Falcon-Lang and Bashforth, 2004)....
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...This allochthonous assemblage was likely fluvially transported from upland forested regions (Falcon-Lang and Bashforth, 2004)....
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Journal Article•DOI•

Incised channel fills containing conifers indicate that seasonally dry vegetation dominated Pennsylvanian tropical lowlands

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Howard J. Falcon-Lang¹, W. John Nelson, Scott D. Elrick, Cindy V. Looy², Philip R. Ames, William A. DiMichele³ - Show less +2 more•Institutions (3)

Royal Holloway, University of London¹, University of California, Berkeley², National Museum of Natural History³

01 Oct 2009-Geology

TL;DR: The authors showed that xerophytic woodchian conifers were temporally dominant in the Pennsylvanian tropical lowlands of the United States, and that seasonally dry vegetation dominated instead.

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Abstract: The idea that the Pennsylvanian tropical lowlands were temporally dominated by rainforest (i.e., the Coal Forest) is deeply ingrained in the literature. Here we challenge two centuries of research by suggesting that this concept is based on a taphonomic artifact, and that seasonally dry vegetation dominated instead. This controversial finding arises from the discovery of a new middle Pennsylvanian (Moscovian) fossil plant assemblage in southeast Illinois, United States. The assemblage, which contains xerophytic walchian conifers, occurs in channels incised into a calcic Vertisol below the Baker Coal. These plants grew on seasonally dry tropical lowlands inferred to have developed during a glacial phase. This xerophytic flora differs markedly from that of the typical clubmoss-dominated Coal Forest developed during deglaciation events. Although preserved only very rarely, we argue that such xerophytic floras were temporally as dominant, and perhaps more dominant, than the iconic Coal Forests, which are overrepresented in the fossil record due to taphonomic megabias. These findings require the iconography of Pennsylvanian tropical lowlands to be redrawn.

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124 citations

Cites background from "Pennsylvanian uplands were forested..."

...While this explanation may account for some of these fossils (Falcon-Lang and Bashforth, 2004), an alternative possibility is that the xerophytic assemblages record continent-wide changes in lowland vegetation driven by the onset of tropical aridity during glacial phases (Falcon-Lang, 2004)....
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...Pennsylvanian wood with these properties is characteristic of juvenile cordaitaleans (Falcon-Lang and Bashforth, 2004) and mature wood of conifers....
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References

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Journal Article•DOI•

Tree Rings and Climate

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Raymond S. Bradley, Harold C. Fritts

01 Feb 1978-Arctic and alpine research

4,668 citations

Book•

Tree Rings and Climate

[...]

Harold C. Fritts

11 Nov 2012

TL;DR: In this paper, a summary of basic dendrochronology, especially its application to Beams from these activities that various statistical methods such as they are covered, is given.

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Abstract: This classic title, originally printed in 1976, contains a lucid description and summary of basic dendrochronology, especially its application to Beams from these activities that various statistical methods such as they are covered. They are basically recording a highly, localized analyses possible therefore. Trees grow all places on natural forces. The dendroclimatology that has quickly made climate record initial. This climate remains a glossary of greatest hits to compensate for more than previously estimated. Our study actually does none of natural warm period then sealed to calibrate growth.

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4,206 citations

Journal Article•DOI•

Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events

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Thomas J. Algeo¹, Stephen E. Scheckler²•Institutions (2)

University of Cincinnati¹, Virginia Tech²

29 Jan 1998-Philosophical Transactions of the Royal Society B

TL;DR: This model provides a framework for understanding links between early land plant evolution and coeval marine anoxic and biotic events, but further testing of Devonian terrestrial-marine teleconnections is needed.

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Abstract: The Devonian Period was characterized by major changes in both the terrestrial biosphere, e.g. the evolution of trees and seed plants and the appearance of multi-storied forests, and in the marine biosphere, e.g. an extended biotic crisis that decimated tropical marine benthos, especially the stromatoporoid-tabulate coral reef community. Teleconnections between these terrestrial and marine events are poorly understood, but a key may lie in the role of soils as a geochemical interface between the lithosphere and atmosphere/hydrosphere, and the role of land plants in mediating weathering processes at this interface. The effectiveness of terrestrial floras in weathering was significantly enhanced as a consequence of increases in the size and geographic extent of vascular land plants during the Devonian. In this regard, the most important palaeobotanical innovations were (1) arborescence (tree stature), which increased maximum depths of root penetration and rhizoturbation, and (2) the seed habit, which freed land plants from reproductive dependence on moist lowland habitats and allowed colonization of drier upland and primary successional areas. These developments resulted in a transient intensification of pedogenesis (soil formation) and to large increases in the thickness and areal extent of soils. Enhanced chemical weathering may have led to increased riverine nutrient fluxes that promoted development of eutrophic conditions in epicontinental seaways, resulting in algal blooms, widespread bottomwater anoxia, and high sedimentary organic carbon fluxes. Long-term effects included drawdown of atmospheric pCO2 and global cooling, leading to a brief Late Devonian glaciation, which set the stage for icehouse conditions during the Permo-Carboniferous. This model provides a framework for understanding links between early land plant evolution and coeval marine anoxic and biotic events, but further testing of Devonian terrestrial-marine teleconnections is needed.

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571 citations

"Pennsylvanian uplands were forested..." refers background in this paper

...…relate to a significant event in the ‘‘greening of the Earth’’ (Falcon-Lang and Scott, 2000), but also because the colonization of upland environments would have exerted an enormous impact on continental weathering rates and hence on the global carbon cycle and climate (Algeo and Scheckler, 1998)....
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Journal Article•DOI•

Origin and evolution of gymnosperms

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Robert A. Price, Charles B. Beck

01 Nov 1989-Taxon

327 citations

"Pennsylvanian uplands were forested..." refers background in this paper

...…the presence of a septate Artisia pith cavity, pycnoxylic wood referable to Dadoxylon materiarium Dawson, and branches bearing the helically arranged bases of large leaves (Rothwell, 1988); 127 specimens are sufficiently well preserved to identify from which part of the tree they were derived....
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Book•

Ecology of the southern conifers

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Neal J. Enright, Robert S. Hill

01 Jan 1995

229 citations

"Pennsylvanian uplands were forested..." refers background in this paper

...Mature cordaitaleans appear to have had a sparse canopy topping an unbranched lower trunk similar to Araucaria araucana (Enright and Hill, 1995)....
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