Limited short-term impact of lemming grazing on vascular plants under experimentally reduced predation in the High Arctic
2025
Gilles Gauthier | Guillaume Slevan-Tremblay | Dominique Fauteux | Esther Lévesque
Population fluctuations of lemmings in the High Arctic appear to be driven by predator–prey interactions. However, lemming grazing can sometimes have a strong impact on the vegetation during population peaks, suggesting a possible role of plant–herbivore interactions. We use a large-scale experiment where predators were excluded to investigate whether predator reduction could have cascading effects on the vegetation through an increase in lemming densities in the Canadian Arctic. Morphological traits and biomass of Salix arctica and the biomass of Poaceae and Juncaceae were sampled inside and outside lemming exclosures. We detected signs of lemming grazing on the number of buds and catkins of S. arctica at snowmelt, and stem length, stem growth, and number of leaves during the summer but the impact was relatively small. We did not detect an impact of grazing on plant biomass during the summer. We also found limited evidence that the impact of grazing was higher in the predator exclosure even though lemming density increased up to two-fold. Our results suggest that the short-term impact of lemmings on vascular plants is relatively small and that an experimental increase in lemming density did not have a cascading effect on the plants consumed by these herbivores in the Canadian Arctic.
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