Background information
Woodland caribou (Rangifer tarandus caribou) are listed as Threatened in Canada (Committee on the Status of Endangered Wildlife in Canada, 2002). Their habitat on the boreal plains of northern Alberta is heavily impacted by both natural and anthropogenic disturbances. Throughout their range, oil and gas development and forestry have greatly fragmented their habitat through the construction of seismic lines, well pads, and cutblocks (Latham et al. 2011). This fragmentation reduces their overall available habitat, and makes them more vulnerable to predation (Latham et al. 2011). In addition to human disturbances, the boreal forest is frequented by large, stand replacing fires. Several previous studies have looked the impact of fire on caribou habitat and forage resources (McMullin et al. 2011, Dunford et al. 2006), however these studies have not been applied to boreal plains habitats in northeastern Alberta.
Terrestrial lichens of the genus Cladonia are an important source of forage for woodland caribou, particularly during the winter when other food sources are scarce (Klein, 1982). These slow-growing lichens form large mats that can dominate the forest floor, but can take decades to reach that level of abundance. After a large fire, lichens are removed from the landscape, and caribou will avoid these burned sites until lichen mats have recovered (Environment Canada, 2012). Previous research suggests that the recovery threshold for Cladonia lichens after a fire is approximately 40 years (Environment Canada, 2012)
Understanding the recovery rate of lichen and quantifying the available biomass of forage lichens is key for identifying and managing woodland caribou critical habitat. The aim of our study is to quantify the rate of recovery of Cladonia lichens in upland jack pine stands within known caribou ranges in the boreal plains of northeastern Alberta. We look at lichen cover and biomass in stands of various age classes within our study area, and compare their total biomass over time. Additionally, caribou in our study area spend much of their time in peatland habitats (Dunford et al. 2006), so we survey available biomass in peatlands within known caribou ranges, and compare that total biomass to lichen biomass in upland stands. We establish conversion factors for cover:biomass ratios based on field measurements, and then apply these conversion factors at the transect level to estimate total biomass for each site. The larger scope of my project will be to apply these conversion factors at the landscape scale, using GIS and remote sensing techniques, to create a map of available forage resources for struggling caribou populations. While some work has been done to predict lichen abundance based on ecosite type and vegetation cover (Alberta Biodiversity Monitoring Institute, 2018), my study will provide a more accurate estimate of available biomass based on direct cover measurements from satellite imagery. This product can be used to help guide land use decisions and protected areas management, as well as fire management, as areas of high lichen biomass may be targeted for conservation.
Terrestrial lichens of the genus Cladonia are an important source of forage for woodland caribou, particularly during the winter when other food sources are scarce (Klein, 1982). These slow-growing lichens form large mats that can dominate the forest floor, but can take decades to reach that level of abundance. After a large fire, lichens are removed from the landscape, and caribou will avoid these burned sites until lichen mats have recovered (Environment Canada, 2012). Previous research suggests that the recovery threshold for Cladonia lichens after a fire is approximately 40 years (Environment Canada, 2012)
Understanding the recovery rate of lichen and quantifying the available biomass of forage lichens is key for identifying and managing woodland caribou critical habitat. The aim of our study is to quantify the rate of recovery of Cladonia lichens in upland jack pine stands within known caribou ranges in the boreal plains of northeastern Alberta. We look at lichen cover and biomass in stands of various age classes within our study area, and compare their total biomass over time. Additionally, caribou in our study area spend much of their time in peatland habitats (Dunford et al. 2006), so we survey available biomass in peatlands within known caribou ranges, and compare that total biomass to lichen biomass in upland stands. We establish conversion factors for cover:biomass ratios based on field measurements, and then apply these conversion factors at the transect level to estimate total biomass for each site. The larger scope of my project will be to apply these conversion factors at the landscape scale, using GIS and remote sensing techniques, to create a map of available forage resources for struggling caribou populations. While some work has been done to predict lichen abundance based on ecosite type and vegetation cover (Alberta Biodiversity Monitoring Institute, 2018), my study will provide a more accurate estimate of available biomass based on direct cover measurements from satellite imagery. This product can be used to help guide land use decisions and protected areas management, as well as fire management, as areas of high lichen biomass may be targeted for conservation.
Figure 1. Woodland caribou (Rangifer tarandus caribou) are reliant on lichens of the Cladonia genus for forage, particularly in winter months.
Objectives
Based on the knowledge gaps surrounding lichen recovery in Alberta's boreal forest, the goal of this study is to quantify available lichen biomass within caribou ranges. The first objective of the study is to understand the rate of regeneration of terrestrial forage lichens in upland jack pine stands, and to model which factors may be influencing this regeneration, such as canopy closure, vegetation cover, or ecosite type. The second objective is to model the relationship between cover and biomass in peatland habitats within our study area, in order to quantify the available biomass for foraging caribou. Our third objective is to map available lichen biomass using GIS and remote sensing techniques, in order to create a management tool for land-use planners.
Expected results
Following a large, stand-replacing fire, jack pine regenerates in very dense stands. Lichen is very slow growing and prefers open canopy stands. Based on the dense canopy of jack pines stands following a recent fire, it is expected that lichen biomass will be low in young, regenerating stands (Figure 2), but will increase as the stand ages and the canopy opens. As high lichen abundance is associated with late-successional stands, it is expected that lichen biomass will continue to increase with stand age. In peatlands, a variable water table can create wet conditions that are not conducive to lichen growth. However, telemetry data suggests that caribou spend much of their time in peatlands. It is expected that lichen biomass in peatlands will be high, to support higher levels of caribou foraging, but that lichen distribution will be patchy on the landscape, due to a fluctuating water table (Figure 3).
Figure 2. It is expected that lichen abundance in young, regenerating pine stands will be low due to a dense canopy.
|
Figure 3. Due to a fluctuating water table, but high caribou use, it is expected that in peatlands, lichen biomass will be high but have a patchy distribution.
|