La flore vasculaire alpine du plateau Big Level, au parc national du Gros-Morne, Terre-Neuve

• Published in: Géographie physique et Quaternaire
• Main Authors: Brouillet, Luc, Hay, Stuart, Turcotte, Pierrette, Bouchard, André
• Format: Text
• Language: French
• Published: Les Presses de l'Université de Montréal 1998
• Subjects: Big Level; Granito; Gros Morne National Park; Le Plateau; Crowberry; Newfoundland; Terre-Neuve
• Online Access: http://id.erudit.org/iderudit/004774ar; https://doi.org/10.7202/004774ar

The alpine flora of northeastern North America is well documented, with the exception of the Long Range Mountains of Newfoundland. The gneissic Big Level plateau is one of the largest high altitude plateaus of the Long Range Mountains. Among the alpine habitats encountered, the numerous snowbed communities contribute the most to vascular plant biodiversity with 73 of the 92 species observed in the alpine zone of the plateau. The 21 rare vascular plant species found on the plateau are all in habitats associated with snowbeds. These species represent about 20 % of all rare plants in Gros Morne National Park. Among these, three are southern range extensions from the northern tip of the island : Carex lachenalii, Salix argyrocarpaand Veronica wormskjoldii . The bio- geographic composition of the snowbed flora in the Gulf of St. Lawrence - New England area, with its circumpolar, cordilleran, northeastern North American and amphi-Atlantic elements, contributes to the exceptional floristic character of the plateau. The intensive grazing of peripheral Carex swards by the large caribou herd of the plateau represents an interesting ecological characteristic of these alpine snowbeds. Also exceptional is the presence of vast areas of hummocky heath with crowberry and Pickering's reedgrass ( Empetrum - Calamagrostis pick- eringii ). These hummocks are caused by frost disturbance on the gentle slopes of the eastern part of the plateau, and to our knowledge, this type of patterned ground has not been reported from the boreal zone of eastern North America; it is a witness of the severity of winters on the plateau. No other granito-gneissic plateau in eastern North America has such extensive or numerous snowbeds. La flore alpine du nord-est de l'Amérique du Nord est bien documentée à l'exception de celle des monts Long Range, à Terre-Neuve. Le plateau gneissique de Big Level est l'un des plus grands plateaux de haute altitude des monts Long Range. Parmi les habitats alpins qui s'y trouvent, les nombreuses combes à neige ...