Introduction
Disturbances, both anthropogenic and natural, cause landscape-level changes to woodland caribou habitat in Canada’s boreal forest. The cumulative effects of disturbances have caused population decline in many regions, leading to listing of woodland caribou as ‘Threatened’ under Canada’s Species at Risk Act. The federal government released a recovery strategy for woodland caribou in 2012, emphasizing the need to limit disturbance in caribou ranges to less than 35% of the total area. The recovery strategy defined disturbances as anthropogenic features such as roads and cutblocks; and areas affected by forest fires within the last 40 years (EC 2012). The federal disturbance model makes little distinction between anthropogenic disturbances and recent burns, despite research suggesting these two disturbance types have different effects on caribou.
Anthropogenic disturbances increase the availability of young forest and deciduous plants, favourable for moose and white-tailed deer, which subsequently increase in abundance. The increased prey density in fragmented landscapes supports a larger wolf population and wolves take advantage of the increased movement rate afforded by linear features such as roads (James et al. 2004; Dickie et al 2016). These mechanisms have increased predation rate of wolves on caribou and are a primary cause of caribou population declines across portions of Canada’s boreal forest with industrial development.
However, much of the range of boreal woodland caribou has little industrial development, and the primary disturbance agent is large, stand-replacing forest fires. These fires often consume the forest floor and the ground lichens that caribou rely upon as a major source of food. Lichens are slow-growing and are generally assumed to take 40 years to fully recover after a fire. As a result, burns less than 40 years old are considered unsuitable habitat for caribou (EC 2012). However, in recent years some researchers have challenged the contention that fires contribute to caribou population declines, citing the ability of caribou to buffer the effects of fires by occupying large home ranges (Dalerum et al. 2007), and evidence of caribou occasionally making use of residual habitats within burn perimeters (Skatter et al. 2017). This has caused the federal recovery strategy to come under increasing scrutiny and has stimulated research across the Boreal Shield to disentangle the effects of forest fires on woodland caribou.
We hope to contribute to our knowledge of caribou-fire ecology by studying the influence of fires on ground lichens. After characterizing post-fire lichen recovery, we intend to map lichen abundance across the study area and use caribou telemetry locations to study caribou foraging behavior in a landscape with frequent forest fires. Forage resources are thought to be an important bottom-up mechanism regulating woodland caribou populations, and this study will improve our knowledge of caribou living in landscapes with frequent forest fires.
Objectives
1. Characterize post-fire recovery of ground lichens*
2. Map the distribution and abundance of ground lichens in a landscape with high fire disturbance
3. Investigate patterns in habitat selection with respect to availability of ground lichens
*Only Objective 1 will be addressed as part of this RENR 711 project.
Expected Results
Sampling was stratified by the two dominant upland ecosites found in the study area. Sparse conifer is characterized by very shallow soil with exposed bedrock and low diversity of herbaceous and shrubby vegetation (Figure 1). Dense conifer is characterized by deeper soils, higher tree density and a greater proportion of moss cover (Figure 2). I anticipate that ground lichens will be more abundant in sparse conifer due to greater sun exposure and less competition with mosses.
Ground lichens are notoriously slow-growing and are thus often associated with late-successional stands. However, based on previous studies, I expect significant amounts of ground lichens will be present in stands less than 40 years post-fire, and may provide adequate forage conditions for woodland caribou. Thus, I expect to find an earlier recovery threshold for lichens than the 40 years suggested by Environment Canada.
Disturbances, both anthropogenic and natural, cause landscape-level changes to woodland caribou habitat in Canada’s boreal forest. The cumulative effects of disturbances have caused population decline in many regions, leading to listing of woodland caribou as ‘Threatened’ under Canada’s Species at Risk Act. The federal government released a recovery strategy for woodland caribou in 2012, emphasizing the need to limit disturbance in caribou ranges to less than 35% of the total area. The recovery strategy defined disturbances as anthropogenic features such as roads and cutblocks; and areas affected by forest fires within the last 40 years (EC 2012). The federal disturbance model makes little distinction between anthropogenic disturbances and recent burns, despite research suggesting these two disturbance types have different effects on caribou.
Anthropogenic disturbances increase the availability of young forest and deciduous plants, favourable for moose and white-tailed deer, which subsequently increase in abundance. The increased prey density in fragmented landscapes supports a larger wolf population and wolves take advantage of the increased movement rate afforded by linear features such as roads (James et al. 2004; Dickie et al 2016). These mechanisms have increased predation rate of wolves on caribou and are a primary cause of caribou population declines across portions of Canada’s boreal forest with industrial development.
However, much of the range of boreal woodland caribou has little industrial development, and the primary disturbance agent is large, stand-replacing forest fires. These fires often consume the forest floor and the ground lichens that caribou rely upon as a major source of food. Lichens are slow-growing and are generally assumed to take 40 years to fully recover after a fire. As a result, burns less than 40 years old are considered unsuitable habitat for caribou (EC 2012). However, in recent years some researchers have challenged the contention that fires contribute to caribou population declines, citing the ability of caribou to buffer the effects of fires by occupying large home ranges (Dalerum et al. 2007), and evidence of caribou occasionally making use of residual habitats within burn perimeters (Skatter et al. 2017). This has caused the federal recovery strategy to come under increasing scrutiny and has stimulated research across the Boreal Shield to disentangle the effects of forest fires on woodland caribou.
We hope to contribute to our knowledge of caribou-fire ecology by studying the influence of fires on ground lichens. After characterizing post-fire lichen recovery, we intend to map lichen abundance across the study area and use caribou telemetry locations to study caribou foraging behavior in a landscape with frequent forest fires. Forage resources are thought to be an important bottom-up mechanism regulating woodland caribou populations, and this study will improve our knowledge of caribou living in landscapes with frequent forest fires.
Objectives
1. Characterize post-fire recovery of ground lichens*
2. Map the distribution and abundance of ground lichens in a landscape with high fire disturbance
3. Investigate patterns in habitat selection with respect to availability of ground lichens
*Only Objective 1 will be addressed as part of this RENR 711 project.
Expected Results
Sampling was stratified by the two dominant upland ecosites found in the study area. Sparse conifer is characterized by very shallow soil with exposed bedrock and low diversity of herbaceous and shrubby vegetation (Figure 1). Dense conifer is characterized by deeper soils, higher tree density and a greater proportion of moss cover (Figure 2). I anticipate that ground lichens will be more abundant in sparse conifer due to greater sun exposure and less competition with mosses.
Ground lichens are notoriously slow-growing and are thus often associated with late-successional stands. However, based on previous studies, I expect significant amounts of ground lichens will be present in stands less than 40 years post-fire, and may provide adequate forage conditions for woodland caribou. Thus, I expect to find an earlier recovery threshold for lichens than the 40 years suggested by Environment Canada.