scholarly journals Determination de l age de l epinette noire (picea mariana) en sous-etage de peupliers faux-trembles (populus tremuloides) dans la foret boreale Quebec

1996 ◽  
Author(s):  
Annie Desrochers
Keyword(s):  
Populus Tremuloides ◽  
Picea Mariana ◽  
Epinette Noire

scholarly journals Histoire tardiglaciaire et postglaciaire de la végétation au mont Shefford, Québec

2011 ◽  
Vol 32 (1) ◽  
pp. 81-93 ◽  
Author(s):  
Pierre Richard
Keyword(s):  
Populus Tremuloides ◽  
Picea Mariana ◽  
Acer Rubrum ◽  
Myrica Gale ◽  
Donnant Lieu

L’analyse pollinique d’une cuvette tourbeuse au mont Shefford, Québec, révèle une première phase lacustre de 11400 à 4 200 ans environ avant l’actuel. Le site fut par la suite occupé par une tourbière à Ericacées et Myrique baumier (Myrica gale), puis par une aulnaie à Alnus rugosa et enfin, par une forêt dominée par l'érable rouge (Acer rubrum). La végétation régionale, après la déglaciation, fut d’abord représentée par un désert de type périglaciaire 11400 ans avant l’actuel (AA), puis par une toundra herbacée d'abord, arbustive ensuite, de 11 400 à 11 100 ans AA. L’afforestation s’est effectuée par des peuplements ouverts d’épinette (Picea mariana) et de peuplier faux-tremble (Populus tremuloides), donnant lieu à une pessière ouverte jusque vers 10 100 ans AA. Le domaine de la sapinière à bouleau blanc peut être proposé pour la végétation couvrant la période de 10 100 à 7500 ans AA, après quoi le domaine de l’érablière à tilleul s’est constitué et a dominé jusqu’à nos jours. Le diagramme du mont Shefford est proposé comme diagramme standard en raison du caractère particulièrement complet des séquences polliniques, les plus anciennes étant contemporaines de l’épisode de Saint-Narcisse (moraine frontale). Des aspects méthodologiques portant sur l’interprétation en termes de végétation sont discutés, et les principales zones d’assemblage pollinique du Québec méridional central sont présentées.

Understorey vegetation in boreal Picea mariana and Populus tremuloides stands in British Columbia

2003 ◽  
Vol 14 (2) ◽  
pp. 173-184 ◽  
Author(s):  
Hong Qian ◽  
Karel Klinka ◽  
Rune H. Økland ◽  
Pavel Krestov ◽  
Gordon J. Kayahara
Keyword(s):  
British Columbia ◽  
Populus Tremuloides ◽  
Picea Mariana ◽  
Understorey Vegetation

scholarly journals Vegetation of the Continental Northwest Territories at 6 ka BP

2007 ◽  
Vol 49 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Glen M. MacDonald
Keyword(s):  
Northwest Territories ◽  
Populus Tremuloides ◽  
Picea Mariana ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Arctic Tundra ◽  
Range Limits ◽  
Mackenzie Delta ◽  
Delta Region ◽  
Low Arctic

ABSTRACTPollen records are used to reconstruct vegetation in the continental Northwest 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 throughout their modern ranges in the Boreal and Subarctic Forest Zones by 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 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 of the forest was similar to modern Low Arctic Tundra. Development of extensive Sphagnum peatlands had begun in the forested areas and the adjacent Low Arctic Tundra. Palaeoecological information regarding vegetation at 6000 BP remains lacking for the northeastern half of the study area. Therefore, the nature of the vegetation in much of the area now occupied by Low Arctic and Middle Arctic Tundra remains unknown. Important 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 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.

Photosynthesis of black spruce, jack pine, and trembling aspen after artificially induced frost during the growing season

1998 ◽  
Vol 28 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Manuel Lamontagne ◽  
Hank Margolis ◽  
Francine Bigras
Keyword(s):  
Populus Tremuloides ◽  
Picea Mariana ◽  
Tree Species ◽  
Pinus Banksiana ◽  
Black Spruce ◽  
Recovery Period ◽  
Growing Season ◽  
Jack Pine ◽  
Trembling Aspen ◽  
Monitoring Period

Light-saturated photosynthesis following artificial frosts was monitored for black spruce (Picea mariana (Mill.) BSP), jack pine (Pinus banksiana Lamb.), and trembling aspen (Populus tremuloides Michx.). None of the species exposed to -9°C in May or to -6 and -9°C in August recovered within the 23- and 14-day monitoring periods, respectively. Black spruce and jack pine treated at -6°C in May recovered within 5 and 23 days, respectively. Black spruce treated at -3°C in August recovered within 10 days. Frosts were applied to the upper and lower canopies of mature black spruce and jack pine in June and to mature trembling aspen in July. For black spruce, the lower canopy did not recover whereas the upper canopy partially recovered over the 10-day monitoring period. For jack pine and trembling aspen, there were no differences in recovery between canopy levels. Jack pine treated at -5.5°C recovered within the 10-day monitoring period whereas at -8.5°C, it only partially recovered. Although recovery period varied with species, phenological state, and frost temperature, gradual recovery of photosynthesis over 5-21 days seems a reasonable modelling algorithm for boreal tree species when growing season frosts lower than -3°C occur. However, cooling rates in our experiments were greater than those that normally occur in nature.

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