Distribution of barren‐ground caribou during winter in response to fire

Abstract

Abstract. We investigated the influence of past fires on the large-scale distribution of barren-ground caribou (Rangifer tarandus groenlandicus) in the Northwest Territories, Canada, during winter. We used an information-theoretic approach and data describing fire history, vegetation, and predation risk to develop resource selection functions that explained caribou distribution on early-and late-winter ranges. We evaluated multiple sets of models constructed across years for all caribou (pooled models) and for individual caribou by period (early and late winter). Winter range habitats important to caribou were characterized by a high percentage of ground cover of lichen and herbaceous forage and a close proximity to lakes and rivers. Although caribou avoided areas densely populated with burns, there was considerable use of early-seral habitats as well as areas adjacent to the burn boundary. Disparate selection strategies among caribou highlight the importance of investigating both individual and global resource selection models. These results suggest that at some spatial and temporal scales, individual barren-ground caribou may be less averse to fire than previously thought.

Observed and predicted effects of climate change on Arctic caribou and reindeer

“…Caribou tend to select mature stands (>40 years old) containing relatively abundant lichen cover (Joly et al 2003) and avoid immature stands, although recent studies have found that there may be more individual variation in the use of these areas than previously thought (Anderson and Johnson 2014), and some individuals may take advantage of these areas for increased vascular forage (Joly et al 2003). Caribou may also use immature stands as habitat for movement (Rickbeil et al 2016) or possibly to reduce predation risk through enhanced visibility (Anderson and Johnson 2014). The effects of fire on caribou winter habitat, and associated avoidance by individuals, extend well beyond the short-term loss of vegetation due to the recovery time of lichen species.…”

“…Regardless of whether caribou populations rely on forage species other than lichens in the winter, what is supported by both recent (Joly et al 2009;Anderson and Johnson 2014) and older studies (Scotter 1964) is that during the winter barren-ground caribou select mature forest stands with productive lichen communities and avoid immature and recently burned stands. We believe that it is therefore a reasonable and precautionary approach to consider it likely that the reduction of abundant lichen forage on the winter range, whether through increased fire activity or altered community composition, can lead to negative effects on barren-ground caribou populations through changes in habitat use and behaviour or abundance.…”

“…Over time, research has led to opposing views on the significance of the effects of fire on migratory caribou (Bergerud 1974;Klein 1982), although at present there is general agreement in the literature that wildfire is detrimental to caribou winter range. At the population level, caribou tend to avoid recently burned areas (Thomas et al 1996;Joly et al 2003Joly et al , 2009Barrier and Johnson 2012;Anderson and Johnson 2014), with selection by caribou primarily determined by the reduction in mature habitat and available lichen forage. Caribou tend to select mature stands (>40 years old) containing relatively abundant lichen cover (Joly et al 2003) and avoid immature stands, although recent studies have found that there may be more individual variation in the use of these areas than previously thought (Anderson and Johnson 2014), and some individuals may take advantage of these areas for increased vascular forage (Joly et al 2003).…”

“…At the population level, caribou tend to avoid recently burned areas (Thomas et al 1996;Joly et al 2003Joly et al , 2009Barrier and Johnson 2012;Anderson and Johnson 2014), with selection by caribou primarily determined by the reduction in mature habitat and available lichen forage. Caribou tend to select mature stands (>40 years old) containing relatively abundant lichen cover (Joly et al 2003) and avoid immature stands, although recent studies have found that there may be more individual variation in the use of these areas than previously thought (Anderson and Johnson 2014), and some individuals may take advantage of these areas for increased vascular forage (Joly et al 2003). Caribou may also use immature stands as habitat for movement (Rickbeil et al 2016) or possibly to reduce predation risk through enhanced visibility (Anderson and Johnson 2014).…”

“…The effects of fire on caribou winter habitat, and associated avoidance by individuals, extend well beyond the short-term loss of vegetation due to the recovery time of lichen species. Most forage lichens require in excess of 50 years to reach relevant biomass for consumption (Maikawa and Kershaw 1976), with 60 to 80 years post-fire necessary to achieve the largest abundance of forage lichens (Thomas 1998;Anderson and Johnson 2014). In some cases, only 180 years after burning do primary forage lichen species (e.g., Cladina rangiferina, Cladina stellaris) reach maximum biomass (Collins et al 2011).…”