Êtes-vous un étudiant de l'EPFL à la recherche d'un projet de semestre?
Travaillez avec nous sur des projets en science des données et en visualisation, et déployez votre projet sous forme d'application sur GraphSearch.
Concept
Fern spike
Résumé
In paleontology, a fern spike is the occurrence of unusually high spore abundance of ferns in the fossil record, usually immediately (in a geological sense) after an extinction event. The spikes are believed to represent a large, temporary increase in the number of ferns relative to other terrestrial plants after the extinction or thinning of the latter. Fern spikes are strongly associated with the Cretaceous–Paleogene extinction event, although they have been found in other points of time and space such as at the Triassic-Jurassic boundary. Outside the fossil record, fern spikes have been observed to occur in response to local extinction events, such as the 1980 Mount St. Helens eruption.
Extinction events have historically been caused by massive environmental disturbances, such as meteor strikes. Volcanic eruptions can also wipe out local ecosystems through pyroclastic flows and landslides, leaving the ground bare for new colonization. For a population to recover and thrive after such an event, it must be able to tolerate the conditions of the disturbed environment. Ferns have multiple characteristics which predispose them to grow in those environments.
Plants generally reproduce with spores or seeds, meaning those will be what germinates in a disaster's aftermath. But spores have advantages over seeds in the environmental conditions produced by a disaster. They are generally produced in higher numbers than seeds, and are smaller, aiding wind dispersal. While many wind-dispersed pollens of seed plants are smaller and farther dispersed than spores, pollen cannot germinate into a plant and must land in a receptive flower. Some seed plants also require animals to disperse their seeds, which may not be present after a disaster. These characteristics allow ferns to rapidly colonize an area with their spores.
Fern spores require light to germinate. Following major disturbances that clear or reduce plant life, the ground would receive ample sunlight that may promote spore germination.
Source officielle
À propos de ce résultat
Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.