520, ch. de la Côte-Sainte-Catherine Building
520, ch. de la Côte-Sainte-Catherine
Université de Montréal
Global climate change, particularly in the Arctic, is causing significant changes to vegetation and permafrost. Among other things, global warming has caused a gradual colonization of herbaceous tundra by shrub species. This change in vegetation cover causes significant changes in the energy balance of the surface and thus greatly influences the thermal and physical properties of the permafrost, and more particularly the ice-rich upper part of the permafrost (transient layer and intermediate layer). Knowing that the stability of ground ice allows biogeosystems to maintain their ecosystem functions over long periods of time, ground ice thawing can result in significant topographic and ecological changes. These very deep disturbances may trigger positive feedback to regional and global warming.
In parallel, a population explosion of Greater Snow Goose populations (Chen caerulescens atlantica) is observed at the circumpolar scale, which leads to an increase in herbivory pressure on the arctic vegetation. Bylot Island has one of the largest snow goose colonies in the world, counting more than 100,000 geese in the Qarlikturvik Valley during the summer season. The impact of the presence of these herbivores on the dynamics of arctic vegetation and underlying permafrost requires special scientific attention. The main objective of my project is therefore to evaluate the vegetation and permafrost conditions following an experiment on herbivory and fertilization of arctic vegetation on the long term (20 years), the longest experience of the kind carried out in the Arctic.
The study site is located on Bylot Island (Nunavut), in the southern plain of the island (Qarlikturvik Valley), where 52 plots are distributed within ice-wedge polygons of different types and colonized by vegetation.
The methodology will consist of a permafrost drilling campaign in the plots. Permafrost (sediment, carbon) and ice in the soil (volume, geometry, geochemistry, age) will be characterized in the laboratory. The permafrost cores will be preserved frozen and analyzed using a Ct-scan to obtain a digital archive.
The study will contribute to a collaborative project (FRQNT-team, principal investigator: V. Maire (UQTR), collaborators: G. Gauthier (ULaval), E. Lévesque (UQTR), L. Rochefort (ULaval), D. Fortier ( UdeM)). The expected results of the research are important for: 1) modelling global changes that currently do not take into account the importance of the ice-rich layers of permafrost; 2) understanding the impact of vegetation dynamics on ice permafrost aggradation and carbon stocks; and 3) understanding the ecosystem response to permafrost degradation given the fundamental control of ground ice over topography and hydrology.