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Understanding the functioning of terrestrial Arctic food webs is essential in a global change context. Many questions remain unclear about population dynamic of lemmings that are known to periodically fluctuate following 3 to 4 year cycles. Lemmings are essential prey in the diet of carnivores living in the Arctic, which brings forward an important debate about how their population density is controlled, whether it is by predation (top-down) or food availability (bottom-up). Primary productivity is low in tundra ecosystems and thus food availability has the potential to contribute to lemming population fluctuations, particularly during peak years. In Scandinavia and Alaska, overgrazing is considered a factor influencing population cycles. However, lemming populations in other arctic and subarctic areas appear to be controlled by predation.
The main goal of my study is to evaluate the indirect impacts of predation on lemming grazing in an experimental setup where predators are excluded. My work is focused on population of brown lemmings (Lemmus sibiricus) and collared lemmings (Dicrostonyx groenlandicus) living on Bylot Island, Nunavut. In absence of predation, we predict that lemming populations will reach densities high enough to have a strong and measurable effect on plants, which should not be the case in areas exposed to predation. This prediction will be tested by measuring grazing impact on vegetation using lemming exclosures inside an 8 ha area fenced since 2013 to exclude predators, and comparing it with the outside where predation occurs.
This project is especially important considering that climate change could affect trophic interactions in this fragile Arctic ecosystem. Environmental disturbances could potentially alter the amplitude of lemming cycles leading to an ecological disruption in the ecosystem. Results from this project could eventually contribute to improve the management of Nordic ecosystems through a better understanding of the trophic interactions.
Fauteux, D., Slevan-Tremblay, G., Gauthier, G., Berteaux, D., 2018. Life in the fast lane: learning from the rare multi-year recaptures of brown lemmings in the High Arctic. Arctic Science, 4(1): 146-151. DOI: 10.1139/AS-2017-0017.
Fauteux, D., Slevan-Tremblay, G., Gauthier, G., Berteaux, D., 2017. Feeding preference of brown lemmings (Lemmus trimucronatus) for plant parts of Arctic willow (Salix arctica). Polar Biology, 40(11): 2329–2334. DOI: 10.1007/s00300-017-2147-7.