Historically, stand development in northern boreal and montane forests was initiated by forest fires. As young trees develop and age after stand initiation forest canopy structure goes through distinctive canopy closure and stand thinning phases. These changes in canopy structure are accompanied by changing temperature, moisture, and light gradients within the canopy and on the forest floor surface. This is a major factor in shaping the composition of forest lichen communities, both epiphytic and terrestrial. Mature and old-growth forest stands, in particular, develop distinctive lichen communities upon which wildlife species depend.
Mature pine forests in the southern Yukon support extensive terrestrial lichens mats used as a winter forage source by caribou.
Both mountain and woodland caribou rely on terrestrial and canopy lichens as a major food source during the winter period. In in many parts of western Canada, however, timber harvesting has reduced the availability of forage lichens for caribou within regional landscapes. Our research examines how alternative forest harvesting systems such as partial-cutting can maintain forest canopy structure required for caribou habitat, or even enhance conditions under which forage lichen growth occurs.
This research has been carried out in partnership with forest licences and land managers, using both operational and research harvesting blocks to address major questions about forest lichen growth and retention. This work provides guidance about required levels of canopy retention needed to maintain forage lichens, as well as addressing questions about best-practices harvesting design.
In shaded forest floor microsites feather-moss mats can infiltrate and replace terrestrial lichens.
Boudreault, C., D.S. Coxson, Y. Bergeron, S. Stevenson, and M. Bouchard. 2013. Do forests treated by partial cutting provide growth conditions similar to old-growth forests for epiphytic lichens? Biological Conservation 159:458–467. http://dx.doi.org/10.1016/j.biocon.2012.12.019
Stevenson, S.K. and D.S. Coxson. 2009. Effects of partial cutting on forage lichens for caribou in a subalpine forest: The Pinkerton Mountain silvicultural system trial revisited 10 years after harvesting. NRES Research Extension Note 3:11 pp. http://www.unbc.ca/assets/nres/nresi_ren_03_stevenson.pdf
Coxson, D.S. and S.K. Stevenson. 2007. Influence of high-contrast and low-contrast forest edges on growth of Lobaria pulmonaria in the inland rainforest, British Columbia. Forest Ecology and Management 259:86–97. http://dx.doi.org/10.1016/j.foreco.2007.07.008
Coxson, D.S. and S.K. Stevenson. 2007. Arboreal forage lichens in partial cuts – a synthesis of research results from British Columbia, Canada. Rangifer 17:155–165. http://dx.doi.org/10.7557/126.96.36.1992