Supervised by:

Pierre Legagneux (Regular Member (Co-researcher))

Co-supervised by:

Dominique Fauteux (Associate Member)

Esther Lévesque (Regular Member (Co-researcher))

Research project description

Cascading effects of lemming predation on High Arctic tundra vegetation

Introduction

Numerous studies have shown that predation is the predominant factor leading to cyclical phases of decline in small northern herbivores. On Bylot Island, located in the Canadian High Arctic in Nunavut, a few studies have measured herbivory pressure from lemmings, whose populations cycle every 3-4 years, and it remained low and short-term, even after abundance peaks. This could possibly be explained by intense grazing shortened by heavy predation during these peaks. Predation could therefore, by trophic cascades, have a significant impact on the structure and composition of the tundra plant community on Bylot Island.

Objectives

The general objective of this project is to determine if there is a cascading effect of lemming predation on the tundra vegetation of Bylot Island, and if so, to quantify it. This is divided into two specific objectives, which are (1) to determine the medium-term effects of a 10-year reduction in predation on plant species consumed by lemmings and (2) to determine whether this is reflected in soil nutrients.

Study Sites

Data for the next study will be collected at Bylot Island, near the CEN station located in the Qarlikturvik Valley (73°N, 80°W) of Sirmilik National Park. More specifically, sampling will be done in trapping grids (mesic grid and predator exclosure), whose lemming density has been monitored for many years.

Material and methods

An experimental design with sampling in grazing with predation (or "normal") situations, grazing without predation (in a large anti-predator exclosure) and no grazing (small lemming exclosures) will be used. The 8.6-hectare predator exclosure, built in 2013, has doubled the density of lemmings each year, both in summer and winter, doubling the lemmings' grazing for 10 years continuously. For each of the treatments, the richness, diversity and biomass of vascular plants consumed by lemmings, the shape and growth rate of willows, and the cover of bryophytes will be measured. Nitrogen and phosphorus concentrations in the soil and the plants themselves will also be measured.

References

Bilodeau, F., Gauthier, G., Fauteux, D., & Berteaux, D. (2014). Does lemming winter grazing impact vegetation in the Canadian Arctic? Polar Biology, 37(6), 845‑857. https://doi.org/10.1007/s00300-014-1486-x Fauteux, D., Gauthier, G.,