Seedling establishment and climate change: the potential for forest displacement of alpine tundra (Mealy Mountains, Labrador, Canada)

Munier, Anne (2006) Seedling establishment and climate change: the potential for forest displacement of alpine tundra (Mealy Mountains, Labrador, Canada). Masters thesis, Memorial University of Newfoundland.

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Abstract

Loss of alpine habitat is of concern due to upslope migration of altitudinal treelines in response to climate change. The possibility of a rise in the tree-line of the Mealy Mountains of Labrador (Canada) was investigated by planting tree seeds and seedlings (Picea mariana, Abies balsamea, and Betula papyrifera) into experimental treatments along an elevational gradient in the tree-line ecotone. Treatments included passive warming with open top chambers; ground disturbance, and herbivore exclosures. Responses in seedling emergence, growth, damage sustained and mortality were monitored over one (A. balsamea, B. papyrifera) or two (P. mariana) growing seasons. Planted seedlings were able to establish and over-winter above present tree-line, but none were observed growing naturally. A lack of viable seeds may be limiting current tree-line migration, though seed viability improves with climate warming. While seedbed conditions and herbivory may eventually control the rate of seedling establishment, the results point to a strong possibility that tree-lines in the Mealy Mountains are capable of migrating upslope, with potentially significant changes or losses to the existing alpine habitat.

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