Consequences of extinction in tropical peat-forming vegetation of the Middle to Late Pennsylvanian (Westphalian-Stephanian)

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5818553

DiMichele, W A ^[1]; Phillips, T L ^[2]

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1. Smithsonian Inst., Washington, DC (United States). Dept. of Paleobiology
2. Univ. of Illinois, Urbana, IL (United States). Dept. of Plant Biology

Peat-forming environments (coals) were major landscape elements of the Pennsylvanian tropics. Mires reached a pantropical zenith during the 9 Ma of the Westphalian when long intervals of similar vegetation were separated by short intervals of rapid change. Differences between successive vegetation types primarily reflect different proportions of several major habitat-specific subfloras within which species turnover occurred. A hierarchy of organizational levels is suggested in which biotic interactions helped structure and constrain patterns of species replacement. Lycopsids were the framework trees of nearly all Westphalian mires; tree ferns and pteridosperm were important subdominants by the late Westphalian. Environmental changes, largely climatic, during the Westphalian-Stephanian transition resulted in extinction of most mire species, particularly trees. Tree ferns dominated Stephanian mires following a short transitional period of small-lycopsid and fern abundance. Tree ferns were cheaply constructed opportunists and their rise in abundance coincided with an increase in species numbers throughout tropical lowlands. Within mires there was an increase in physical size of plants from several major lineages. The structure and dynamics of Stephanian mires differed from the Westphalian; previously sharp distinctions between mires and other lowland floras diminished. The Westphalian to Stephanian vegetational changes suggest that ecosystems can display a brittle'' response to environmental change. Such threshold responses are a likely consequences of levels of extinction high enough to disrupt ecosystem fabric. The success of opportunistic lineages following loss of indigenous mire vegetation constitutes a secondary replacement, with establishment of a new equilibrium within hundreds of thousands of years.

• OSTI ID: 5818553
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
011000* -- Coal
Lignite
& Peat-- Reserves
Geology
& Exploration
AQUATIC ECOSYSTEMS
BIOLOGICAL EXTINCTION
BOUNDARY CONDITIONS
CARBONIFEROUS PERIOD
CLIMATIC CHANGE
COAL DEPOSITS
ECOSYSTEMS
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MATTER
MINERAL RESOURCES
ORGANIC MATTER
ORIGIN
PALEOCLIMATOLOGY
PALEONTOLOGY
PALEOZOIC ERA
PALYNOLOGY
PEAT
PLANTS
RESOURCES
SWAMPS
TERRESTRIAL ECOSYSTEMS
WETLANDS