Paléoécologie de la tourbière du lac Malbaie, dans le massif des Laurentides (Québec) : évaluation du rôle du climat sur l’accumulation de la tourbe
Microscopic (pollen, rhizopods, charcoal) and plant macrofossil analyses were carried out on three cores for a peatland in the Laurentian Highlands (Québec). The objectives were to reconstruct the developmental history and the past hydrological conditions of the peatland, and to infer paleoclimatic...
| Published in: | Géographie physique et Quaternaire |
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| Main Authors: | , |
| Format: | Text |
| Language: | French |
| Published: |
Les Presses de l'Université de Montréal
2000
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| Subjects: | |
| Online Access: | http://id.erudit.org/iderudit/004843ar https://doi.org/10.7202/004843ar |
| Summary: | Microscopic (pollen, rhizopods, charcoal) and plant macrofossil analyses were carried out on three cores for a peatland in the Laurentian Highlands (Québec). The objectives were to reconstruct the developmental history and the past hydrological conditions of the peatland, and to infer paleoclimatic conditions, notably for the moisture balance. The peatland was characterized by contrasting hydrological conditions between the sampling points during its history. Except for the late Holocene, no clear regional hydrological control was revealed by paleobotanical analyses. Peat inception began in a small pond around 10 300 cal. years BP in a shrub tundra, more than 2000 years after the ice retreat. The peat- land dynamics during the early Holocene likely reflects increased biological productivity caused by the continuous warming of the climate after initial harsh conditions. From 8000 to 3000 BP, a general decrease of the net peat accumulation rate for all cores is in part attributed to the activity of nitrogen fixing cyano- bacteria which promotes an important decomposition of the organic matter. An important vertical peat increment occurred during the last 3000 years probably in response to wetter and colder climatic conditions. Des analyses microfossiles (pollen, rhizopodes, charbons de bois) et des macrorestes végétaux ont été réalisées sur trois profils d'une tourbière du massif des Laurentides, au Québec. Les objectifs sont de reconstituer la succession de la végétation locale et les conditions hydrologiques qui ont présidé à l'accumulation de la tourbe en trois points d'échantillonnage, afin d'en inférer certaines conditions du climat, notamment sous l'angle du régime hydrique. Des conditions hydrologiques locales contrastées se sont établies entre les différents secteurs de la tourbière durant son développement. Sauf au cours de l'Holocène supérieur, les analyses paléobotaniques n'ont pas révélé d'influences hydriques claires de nature climatique sur l'accumulation de la tourbe. Le dépôt des premiers ... |
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