Response of Late Carboniferous and Early Permian Plant Communities to Climate Change

Abstract

Late Carboniferous and Early Permian strata record the transition from a cold interval in Earth history, characterized by the repeated periods of glaciation and deglaciation of the southern pole, to a warm-climate interval. Consequently, this time period is the best available analogue to the Recent in which to study patterns of vegetational response, both to glacial-interglacial oscillation and to the appearance of warm climate. Carboniferous wetland ecosystems were dominated by spore-producing plants and early gymnospermous seed plants. Global climate changes, largely drying,forced vegetational changes, resulting in a change to a seed plant-dominated world, beginning first at high latitudes during the Carboniferous, reaching the tropics near the Permo-Carboniferous boundary. For most of this time plant assemblages were very conservative in their composition. Change in the dominant vegetation was generally a rapid process, which suggests that environmental thresholds were crossed, and involved little mixing of elements from the wet and dry floras. The US Government has the right to retain a nonexclusive, royalty-free licence in and to any copyright covering this paper. Key Words ecosystem stability, glaciation, biome, coal, extinction s Abstract Late Carboniferous and Early Permian strata record the transition from a cold interval in Earth history, characterized by the repeated periods of glaciation and deglaciation of the southern pole, to a warm-climate interval. Consequently, this time period is the best available analogue to the Recent in which to study patterns of vegetational response, both to glacial-interglacial oscillation and to the appearance of warm climate. Carboniferous wetland ecosystems were dominated by spore-producing plants and early gymnospermous seed plants. Global climate changes, largely drying, forced vegetational changes, resulting in a change to a seed plant-dominated world, beginning first at high latitudes during the Carboniferous, reaching the tropics near the Permo-Carboniferous boundary. For most of this time plant assemblages were very conservative in their composition. Change in the dominant vegetation was generally a rapid process, which suggests that environmental thresholds were crossed, and involved little mixing of elements from the wet and dry floras.

Delayed fungal evolution did not cause the Paleozoic peak in coal production

“…Such cordaitalean abundance would have elevated the lignin input to peat in these horizons; however, the derived coals are not thicker or more widespread than the earlier or later lycopsid-dominated coals. Furthermore, during the Kasimovian/Gzhelian transition of the Pennsylvanian, Euramerican communities lost most arborescent lycopsids and transitioned to dominance by nonwoody, Psaronius marattialean ferns (34,(45)(46)(47). Stems of these trees had multiple primary xylem cylinders in a parenchyma matrix with a peripheral sclerenchyma zone.…”

Palaeoecology of Macroneuropteris scheuchzeri, and its implications for resolving the paradox of ‘xeromorphic’ plants in Pennsylvanian wetlands

“…Macroneuropteris scheuchzeri was extant during a time of glaciallydriven alternations between humid and more seasonal climates across tropical Pangaea, and the amplitude and mode of these climatic alternations changed through the studied interval (DiMichele et al, 2001;Falcon-Lang, 2004;Fielding et al, 2008b;Rygel et al, 2009). Prior to, and during the early phases, of its range (beginning in the Atokan; early to mid-Moscovian), the tropics were dominantly subjected to humid-to-perhumid climates, meaning that they were relatively wet year-round, even during the more seasonal portions of glacial-interglacial cycles, when peat was not forming (Cecil et al, 2003;Cleal and Thomas, 2005;Cleal et al, 2009).…”

“…Major compositional and structural changes took place in wetland tropical landscapes across the Desmoinesian-Missourian boundary (Middleto-Late Pennsylvanian: Falcon-Lang et al, 2011a). Considerable evidence (e.g., Phillips and Peppers, 1984;Schutter and Heckel, 1985;Cecil, 1990;Winston, 1990;DiMichele et al, 2001;Fielding et al, 2008aFielding et al, , 2008bHeckel, 2008;Rygel et al, 2009;Bishop et al, 2010) suggests a shift in the climate cycle to increased overall dryness (greater seasonal dryness during both the drier intervals and wetter intervals of glaciogenic cycles) at this time, a change reflecting a period of intensified global warming and ice melting in the south polar regions. Beginning at the time of this major climatic shift, the distributional pattern of this species documents continued ecological confinement to the wettest, swampy environments of the Late Pennsylvanian, particularly those associated with some clastic influx.…”

No Major Stratigraphic Gap Exists Near the Middle-Upper Pennsylvanian (Desmoinesian-Missourian) Boundary in North America

“…During interglacial phases (late transgressive to highstand systems tracts), climate was largely humid to subhumid, and tropical forests were dominated by lycopsids, pteridosperms, and tree ferns (DiMichele and Phillips, 1994;DiMichele et al, 2001DiMichele et al, , 2007. In contrast, at intervals approaching glacial maxima, climate was relatively drier and more seasonal, dominated by a variety of gymnosperms that included cordaitaleans, pteridosperms, and conifers (Falcon-Lang et al, 2009; Falcon-Lang and DiMichele, 2010).…”