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Vegetation of the Continental Northwest Territories at 6 Ka BP

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Vegetation of the Continental Northwest Territories at 6 Ka BP Document generated on 09/28/2021 6:09 a.m. Géographie physique et Quaternaire Vegetation of the Continental Northwest Territories at 6 ka BP La végétation des Territoires du Nord-Ouest continentaux à 6 ka BP Die Vegetation der kontinentalen Nordwest-Territorien um 6 ka v.u.Z. Glen M. MacDonald La paléogéographie et la paléoécologie d’il y a 6000 ans BP au Canada Article abstract Paleogeography and Paleoecology of 6000 yr BP in Canada Pollen records are used to reconstruct vegetation in the continental Northwest Volume 49, Number 1, 1995 Territories at 6 ka (6000 14C yr BP). Picea glauca, P mariana, Larix laricina, Populus tremuloides, P. balsamifera, Alnus crispa and A. incana were present URI: https://id.erudit.org/iderudit/033028ar throughout their modern ranges in the Boreal and Subarctic Forest Zones by DOI: https://doi.org/10.7202/033028ar 6000 BP. Pinus banksiana, however, had not yet reached its present northern limits. Population densities of the dominant trees, Picea glauca and Picea mariana, were close to, or as high as, present. In the Mackenzie Delta region See table of contents the range limit of Picea glauca was approximately 25 km north of its modern location just prior to 6000 BP. In contrast, the northern limits of the forest in central Canada were similar to present. The tundra vegetation close to the edge Publisher(s) of the forest was similar to modern Low Arctic Tundra. Development of extensive Sphagnum peatlands had begun in the forested areas and the Les Presses de l'Université de Montréal adjacent Low Arctic Tundra. Palaeoecological information regarding vegetation at 6000 BP remains lacking for the northeastern half of the study ISSN area. Therefore, the nature of the vegetation in much of the area now occupied 0705-7199 (print) by Low Arctic and Middle Arctic Tundra remains unknown. Important 1492-143X (digital) vegetation changes that occurred following 6 ka include : (1) the advance of Pinus banksiana to its present northern range limits, (2) the retreat of the northern range limits of Picea glauca in the Mackenzie Delta region between Explore this journal 6000 and 3500 BP and (3) the rapid and marked increase in the population density of Picea mariana in the treeline zone of the central Northwest Territories at 5000 BP followed by a decline at 4000 BP. Cite this article MacDonald, G. M. (1995). Vegetation of the Continental Northwest Territories at 6 ka BP. Géographie physique et Quaternaire, 49(1), 37–43. https://doi.org/10.7202/033028ar Tous droits réservés © Les Presses de l'Université de Montréal, 1995 This document is protected by copyright law. Use of the services of Érudit (including reproduction) is subject to its terms and conditions, which can be viewed online. https://apropos.erudit.org/en/users/policy-on-use/ This article is disseminated and preserved by Érudit. Érudit is a non-profit inter-university consortium of the Université de Montréal, Université Laval, and the Université du Québec à Montréal. Its mission is to promote and disseminate research. https://www.erudit.org/en/ Géographie physique et Quaternaire, 1995, vol. 49, n° 1, p. 37-43, 4 fig., 1 tabl. VEGETATION OF THE CONTINENTAL NORTHWEST TERRITORIES AT 6 KA BP Glen M. MACDONALD, Department of Geography, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1. ABSTRACT Pollen records are used to RÉSUMÉ La végétation des Territoires du ZUSAMMENFASSUNG Die Vegetation der reconstruct vegetation in the continental Nord-Ouest continentaux à 6 ka BP La re­ kontinentalen Nordwest-Territorien um 6 ka Northwest Territories at 6 ka (6000 14C yr constitution de la végétation de la partie v.u.Z. Man benutzte Pollen-Belege, um die BP). Picea glauca, P mariana, Larix laricina, continentale des Territoires du Nord-Ouest Vegetation in den kontinentalen Nordwest- Populus tremuloides, P balsamifera, Alnus à 6 ka a été faite à partir des données Territorien um 6 ka ( 6000 14C Jahre v.u.Z.) crispa and A. incana were present through­ polliniques. Picea glauca, P mariana, Larix zu rekonstruieren. Picea glauca, P. mariana, out their modern ranges in the Boreal and laricina, Populus tremuloides, P. Larix laricina, Populus tremoluides, P. Subarctic Forest Zones by 6000 BP. Pinus balsamifera, Alnus crispa et A. incana balsamifera, Alnus crispa und A. incana banksiana, however, had not yet reached avaient déjà atteint leur répartition moderne hatten um 6000 v.u.Z. schon ihre moderne its present northern limits. Population den­ dans les zones des forêts boréales et Verteilung in den nôrdlichen und sities of the dominant trees, Picea glauca subarctiques à 6 ka. Pinus banksiana, tou­ subarktischen Waldgùrtelzonen erreicht. and Picea mariana, were close to, or as tefois, n'avait pas encore atteint sa limite Jedoch hatte Pinus banksiana noch nicht high as, present. In the Mackenzie Delta nordique. Les densités de population des seine gegenwârtigen nôrdlichen Grenzen region the range limit of Picea glauca was arbres dominants, Picea glauca et P. erreicht. Die Populations-Dichte der approximately 25 km north of its modern mariana, étaient aussi fortes ou presque vorherrschenden Baume, Picea glauca und location just prior to 6000 BP. In contrast, que maintenant. Dans la région du delta du Picea mariana war fast so hoch oder so the northern limits of the forest in central Mackenzie, Ia limite de Picea glauca était à hoch wie gegenwârtig. In der Gegend des Canada were similar to present. The tundra environ 25 km au nord de sa limite actuelle Mackenzie-Deltas war die Grenze von Picea vegetation close to the edge of the forest juste avant 6 ka. Par contre, la limite sep­ glauca kurz vor 6 ka etwa 25 km nôrdlich was similar to modern Low Arctic Tundra. tentrionale de la forêt dans la partie cen­ von ihrer modernen Position. Im Gegensatz Development of extensive Sphagnum trale du Canada était semblable à l'actuelle. dazu war die nôrdliche Grenze des Waldes peatlands had begun in the forested areas La végétation de la toundra située à proxi­ in Zentralkanada der gegenwârtigen àhnlich. and the adjacent Low Arctic Tundra. mité de la marge forestière était semblable Die Tundra-Vegetation nah an der WaId- Palaeoecological information regarding veg­ à celle de la toundra du bas Arctique mo­ grenze war der modernen Tundra der etation at 6000 BP remains lacking for the derne. Le développement de vastes tour­ niederen Arktis àhnlich. Die Entwicklung northeastern half of the study area. There­ bières à sphaigne était déjà commencé dans ausgedehnter Sphagnum-Torfmoore hatte in fore, the nature of the vegetation in much of les zones forestières et dans la toundra du den bewaldeten Gebieten und der the area now occupied by Low Arctic and bas Arctique adjacente. Les données angrenzenden Tundra der niederen Arktis Middle Arctic Tundra remains unknown. paléoécologiques sur la végétation à ~6 ka begonnen. Fur die nordôstliche Hàlfte des Important vegetation changes that occurred sont déficientes pour la partie nord-est de erforschten Gebiets gibt es keine following 6 ka include: (1) the advance of la région à l'étude. Dès lors, la nature de la palâoôkologische Information in Bezug auf Pinus banksiana to its present northern végétation dans la plus grande partie du die Vegetation um 6000 v.u.Z. Deshalb bleibt range limits, (2) the retreat of the northern territoire maintenant occupée par la toun­ die Art der Vegetation in einem groBen Teil range limits of Picea glauca in the Macken­ dra du bas Arctique et du moyen Arctique des heute von der niederen arktischen und zie Delta region between 6000 and 3500 est encore inconnue. Les grands change­ mittleren arktischen Tundra eingenom- BP and (3) the rapid and marked increase ments apportées à la végétation après menen Gebiets unbekannt. Zu wichtigen in the population density of Picea mariana ~6ka comprennent: 1) la remontée de Vegetationswechseln, die auf 6 ka folgten, in the treeline zone of the central Northwest Pinus banksiana jusqu'à sa limite septen­ gehôren: (1) das Vordringen von Pinus Territories at 5000 BP followed by a decline trionale actuelle, 2) le recul de la limite banksiana zu seiner heutigen nôrdlichen at 4000 BP. septentrionale de Picea glauca dans la ré­ Grenze, (2) der Rùckzug der nôrdlichen gion du delta du Mackenzie entre 6000 et Grenze von Picea glauca im Gebiet des 3500 BP et 3) l'augmentation rapide et pro­ Mackenzie-Deltas zwischen 6000 und 3500 noncée de la densité de la population de v.u.Z. und (3) die schnelle und deutliche Picea mariana dans la zone de la limite des Zunahme in der Populationsdichte von arbres du centre des Territoires du Nord- Picea mariana in der Zone der Baumgrenze Ouest à 5000 BP suivie d'un déclin à 4000 der zentralen Nordwest-Territorien um 5000 BP. v.u.Z., gefolgt von einer Abnahme um 4000 v.u.Z. Manuscrit reçu le 10 juin 1994 ; manuscrit révisé accepté le 8 septembre 1994 38 G.M. MACDONALD INTRODUCTION five months of the summer mean daily temperatures ex­ ceed 00C and July mean daily temperatures are generally In this paper pollen records from lake sediments and greater than 1O0C. peats are used to reconstruct key attributes of the vegeta­ tion of the continental Northwest Territories at 6 ka (6000 The Boreal Zone is characterised by closed forest with '4C years BP). These attributes are: (1) the general geo­ well drained sites dominated by Picea glauca, Pinus graphic distribution of tree species and important shrubs, banksiana, Populus spp. and Betula papyrifera and exten­ (2) the population densities of the dominant boreal conifers, sive lowlands dominated by Picea mariana and Larix laricina Picea glauca (white spruce), P mariana (black spruce) rela­ (larch) on Sphagnum peatlands and fens.
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