Mapping Lichen Biomass

Reindeer lichens (Cladonia rangiferina, C. mitis, C. stellaris) are important winter food sources for woodland caribou, a threatened species in Alberta’s boreal forest. Federal caribou recovery rules use the 40-year post-fire disturbance rule, yet recovery dynamics for lichens are generally unknown – some may recover faster. Mapping winter caribou habitat and understanding post-fire changes in lichen habitat would provide valuable tools for management and recovery. A successful pilot project was initiated in 2017 under ideal visibility conditions, to test feasibility of using UAVs and remote sensing tools to map and quantify terrestrial lichens. This project built on that pilot, applying the same tools under less ideal visibility conditions, in wetland ecosites, and in the oil sands region. Objectives: (1) test methods to measure lichen biomass using remote sensing tools of LiDAR forest structure, multi-spectral satellites, unmanned aerial vehicle (UAV) multi-spectral imagery, and ground photography in wetland and upland sites and typify the oil sands region; (2) develop algorithms to scale ground and UAV measures to larger landscapes; and (3) relate patterns of disturbance history (especially fires of varying ages) to recovery rates of reindeer lichens using field and remote sensing data.

Overall, lichen abundance was highly variable between and within stands. Areas of mature forest were predicted to have more than 20 times the lichen biomass than recent disturbances. Biomass was predicted to be highest in areas of jack pine forest, and in particular in mature jack pine woodland stands that were characterized by having an open canopy (~2700 kg/ha). In contrast, lichen biomass was highly variable in peatlands and dependent largely on local canopy closure. Our preliminary map of predicted ground lichen biomass for the region may be useful for identifying areas of high value winter forage for caribou populations and directing future sampling and research efforts.