Tree Seed Populations at the Treeline in Riviere Aux Feuilles Area, Northern Quebec, Canada

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Abstract
Although relatively high densities of buried but nonviable seeds have been found in forest and krummholz stands at the forest line (black spruce, Picea mariana [Mill.] BSP., and tamarack, Larix laricina [DuRoi] K. Koch, forests) and at the treeline (tamarack) in the Riviere aux Feuilles area, the tree vegetation is not presently being renewed by a seed bank. The concept of a seedling bank appears more appropriate to explain the regeneration pattern of the northernmost tree populations of the forest-tundra in interior northern Quebec. The treeline is in equilibrium with the present climate, although tamarack seed regeneration is episodic. Tamarack seed production does not seem totally limited by the cooling trend of the 1970s, but seed germination is strongly climate-controlled, especially at the treeline where a low percentage of viable seeds has been observed, and where seedlings are rare. Insect predation causes high seed mortality, eventually reducing the tamarack seedling pool, particularly in forest stands.