Fire and Woodland Caribou
(Rangifer tarandus caribou):
An Evaluation of Range in Southeastern Manitoba

James A. Schaefer

Department of Zoology,
The University of Manitoba,
Winnipeg, Manitoba, Canada
R3T 2N2

 

1Present address: Dr. James Schaefer, Department of Biology, Trent University, Peterborough, Ontario, Canada K9L 7B8

 

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Fire and woodland caribou (Rangifer tarandus caribou): an evaluation of range in southeastern Manitoba. M.Sc. thesis, University of Manitoba. 144 pp.

 

Abstract

The effects of fire on the Aikens Lake population of woodland caribou were studied over a two-year period. Quantity, quality, and accessibility of forage were determined in recently-burned (5-year old) habitats, and compared to those in intermediate (37 year) and old-growth (90 - 160 year) condition. These measures were correlated to patterns of habitat utilisation by Aikens caribou over two winters.

Forage productivity was determined by harvesting current growth of vascular plants and biomass of lichens. Quality of forage was inferred from content of acid detergent fibre and published digestibility studies of Rangifer. Accessibility of forage was estimated from the Värriö Snow Index (VSI), and from intersection frequency of windfallen trees.

Burned habitats have suffered a decline in the quality and accessibility of winter forages due to the loss of Cladina lichens, the increase in snow thickness and hardness, and the accumulation of deadfalls. The oldest stands (160 years) showed decreased forage abundance but the most favourable nival conditions. Aikens caribou exploited the remnant lichen supply within the burn, but abandoned burned range in late winter; a synergistic effect between the accumulation of snow and deadfalls is implicated. This behaviour can be modelled with an index that combines VSI and deadfall frequency.

Taiga is not suitable for woodland caribou in its recently-burned and intermediate stages (up to 50 years following fire). Yet fire may be necessary to maintain optimal, long-term lichen resources. Woodland caribou adapt to the short-term detriments, which may not be fully realised until 5 years or more, by abandoning their range. Therefore access to alternative, lichen-rich stands is imperative.

 


 

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