ARCTIC The High Subarctic Forest-Tundra of Northwestern Canada: Position, Width, and Vegetation Gradients in Relation to Climate

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1991
• Subjects: Arctic; Canada; Great Slave Lake; Hudson; Hudson Bay; Northwest Territories; Yukon; Subarctic; subarctique*; toundra; Tundra
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.584.9213; http://pubs.aina.ucalgary.ca/arctic/Arctic45-1-1.pdf

ABSTRACT. A phytogeoclimatic study of the high subarctic region of Canada between Hudson Bay and the Cordillera at the northern Yukon-Mackenzie border was undertaken to provide a verifiable and quantitative synthesis of forest-tundra vegetation ecology. Three field seasons of vegetation and terrain studies provided ground truth for a grid of 1314 black-and-white air photos that cover Ca. 24 % of the forest-tundra and adja-cent low Subarctic and low Arctic. Air photos were analyzed for percentage cover of nine vegetation-terrain types, bedrock and parent materials, landforms, and elevations. The forest-tundra, as bounded by the 1 O: l and 1:lOOO tree:upland tundra cover isolines, spans an average 145 f 72 km (median 131 km) and increases in width from northwest to southeast. The transition from 101 to 1: lO treexpland tundra cover occupies one-fourth to one-half the area of the forest-tundra. Regional slope of the land probably accounts for much of the variation in width of the forest-tundra. Southern outliers of forest-tundra in the northwest are found mainly in areas of high elevation. Across much of the northwest, steep vegetation gradi-ents occur near the northern limit of trees. North of Great Slave Lake, steep vegetation gradients shift from the northern to the southern half of the forest-tundra and maintain this position eastward to Hudson Bay. The forest-tundra of the northwest receives roughly three-fourths the mean annual net radiation available to the southeast and central districts. Key words: air photos, boreal, climate, ecology, forest-tundra, high Subarctic, Northwest Territories, plant geography, tree line, vegetation RÉSUMÉ. On a entrepris une étude phytogéoclimatique de la zone de l’Extrême-Subarctique canadien comprise entre la baie d’Hudson et la cordil-lère, située à la frontière du Yukon-Mackenzie, en vue d’offrir une synthkse vérifiable et quantitative de l’écologie végétale de la forêt-toundra. Trois