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Titolo:
Evolutionary trends in safety factors against wind-induced stem failure
Autore:
Niklas, KJ; Speck, T;
Indirizzi:
Cornell Univ, Dept Plant Biol, Ithaca, NY 14853 USA Cornell Univ Ithaca NY USA 14853 v, Dept Plant Biol, Ithaca, NY 14853 USA Univ Freiburg, Bot Garten, D-79104 Freiberg, Germany Univ Freiburg Freiberg Germany D-79104 Garten, D-79104 Freiberg, Germany
Titolo Testata:
AMERICAN JOURNAL OF BOTANY
fascicolo: 7, volume: 88, anno: 2001,
pagine: 1266 - 1278
SICI:
0002-9122(200107)88:7<1266:ETISFA>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
LAND PLANTS; FUNCTIONAL-ANATOMY; FOSSIL PLANTS; BIOMECHANICS; LECLERCQIA; SPHENOPSIDS; LYCOPOD; ECOLOGY; GEN; NOV;
Keywords:
biomechanics; factors of safety; fossil plants; mechanical stability; wind-loading;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
64
Recensione:
Indirizzi per estratti:
Indirizzo: Niklas, KJ Cornell Univ, Dept Plant Biol, Ithaca, NY 14853 USA Cornell Univ Ithaca NY USA 14853 nt Biol, Ithaca, NY 14853 USA
Citazione:
K.J. Niklas e T. Speck, "Evolutionary trends in safety factors against wind-induced stem failure", AM J BOTANY, 88(7), 2001, pp. 1266-1278

Abstract

We explore the hypothesis that the safety factor against wind-induced stemfailure remained high during early land plant evolution despite an evolutionary increase in height with concomitant increases in wind-induced drag forces, bending stresses, and moments. This hypothesis was examined for 17 Paleozoic plant species assuming that each (1) existed in a densely packed community of conspecifics with equivalent height, (2) coped with the same wind profile (where ambient wind speed decreased toward ground level), but (3)had different within-canopy wind speeds depending on plant height and general morphology. Drag forces, stresses, and moments were computed, and a safety factor was calculated for each taxon using the quotient of its stem-tissue breaking Stress and maximum wind-induced bending stress. The highest factors of safety were calculated among the most ancient rhyniophyte and zosterophyllophyte species examined (e.g., Rhynia and Gasslingia), and, on average, decreased among the taller and geologically younger species. The tallest species examined (e.g., Archaeopteris and Diaphorodendron) had safety factors equal to or higher than those of some of their presumed ancestors (e.g., Psilophyton and Leclercqia). These trends were statistically more robust among rhyniophytes and their presumed descendants. Even though the results comply with the hypothesis, numerous limitations of our protocol exist (e.g., the requirement for reliable whole-plant reconstructions). These are discussed in terms of our theory Nonetheless. we believe our theory and protocol afford a reasonable opportunity to explore the effects of wind on early plant evolution.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/12/20 alle ore 10:07:12