Lobaria pulmonaria abundance as an indicator of macrolichen diversity in Interior Cedar–Hemlock forests of east-central British Columbia

Abstract

Orographic precipitation over interior mountains has resulted in the formation of the inland temperate rainforest, where certain stands are potentially antique and support a rich flora of epiphytic macrolichens. We documented macrolichen diversity across three age-classes in forests of the Interior Cedar–Hemlock biogeoclimatic zone (i.e., ICHwk3 subzone) east of Prince George, British Columbia. Our objectives were to report changes in lichen communities with stand age, identify potential indicators of antiquity, and investigate the functional role of dominant species in the ecosystem. We identified 41 taxa, including 4 alectorioid lichens, 21 foliose chlorolichens, and 16 old-growth-associated chlorolichens and cyanolichens. Older forests supported more species than young or mature forests. The abundance of Lobaria pulmonaria (L.) Hoffm. was strongly correlated with this increase in diversity and may therefore be an appropriate indicator of stand age in the ICH. The increase in L. pulmonaria and other N2-fixing cyanolichens with stand age may have significant implications for forest nitrogen budgets in the interior of British Columbia, where atmospheric nitrogen deposition is relatively low and biological N2 fixation accounts for nearly all of the nitrogen lost to forest harvesting. We hope that this greater understanding of lichen ecology across age-classes will promote sustainable stewardship of the remaining old-growth forests of inland British Columbia.Key words: macrolichen diversity, Interior Cedar–Hemlock zone, Lobaria pulmonaria, indicator species, cyanolichens, stand age.