Expansion récente du mélèze à la limite des forêts (Québec nordique)

Abstract

The contact between tamarack stands and tundra sites, located at the forest limit and at the tree line (Leaf River, Northern Québec), represents colonization ecotones where tree populations react to climatic change. At the forest limit, the ecotones are about 20 m wide and are supporting most of the young tamarack populations established from nearby forest seed bearers. Tamarack seedlings and saplings established mostly on moss carpets between 1940 and 1970 during the recent climatic warming. At the altitudinal and the latitudinal tree lines, seedling establishment was rather unimportant, considering the very low tamarack density and the absence of black spruce seedlings. The recent climatic warming had probably influenced the consolidation of preexisting tree populations more than the position of the tree line.