E-mail : joannie.savard.1@ulaval.ca

Alpine summit vegetation dynamics of the boreal forest
Direction :
Serge Payette


The boreal forest covers approximately 70 % of Québec’s surface, and is characterized by a mosaic of stands varying in density and age as a result of fire, the principal disturbance. Several mountain summits within the boreal forest that were once covered by forest are now covered by tundra vegetation. The flora of these tundra summits consists of an assemblage of arctic-alpine and boreal species, all in varying proportion according to site conditions such as altitude, latitude and time lapsed since the opening of the forest. The objective of this study is to establish an inventory of the arctic-alpine vegetation on the alpine summits of the boreal biome, with regards to latitude and the period of deforestation. The alpine vegetation will be analysed as a function of altitude, time since deforestation and opening of each tundra site, soil conditions, the surface occupied by the tundra on each summit as well its distance to the forest tundra and arctic tundra regions. This study takes place within the Monts des Éboulements, the Montagnes Blanches, the Monts Otish, as well as the Caniapiscau Reservoir and Lake Bienville area, between 70 °W and 72 °W. In each site, the frequency of each plant species will be calculated along two 75 m long transects. Charcoal will be sampled at the organic/mineral soil horizon interface in order to obtain radiocarbon dates of the fires from the pre-existing forests on each tundra summit studied. The soil characteristics will also be measured (pH, thickness of organic material, granulometry) to ensure similarities between sites. Both the age and size structure of the arborescent species occupying the tundra summits will be determined in order to evaluate their developmental stage (progressive or regressive) in function with environmental conditions. Two summits will be selected in each region along a latitudinal transect in order to evaluate the biodiversity of the tundra sites with regards to latitude and time since deforestation. The aim of this study is to evaluate the oldness and the resilience of the arctic-alpine species in function with current conditions and future climate change that will eventually favour a return of the boreal forest to the mountain summits.