Epiphytic macrolichen cover, richness and composition in young successional boreal forest: A comparison of fire and logging disturbance

Abstract

Epiphytic macrolichens are indicators of environmental quality and forest heath. Stand-replacing disturbances such as wildfire and harvesting may have different impacts on epiphytic macrolichens, but previous studies have confounded the effects of disturbance origin with those of stand age. It remains unknown whether epiphytic macrolichens respond differently to fire vs. harvesting. We examined the temporal dynamics of epiphytic macrolichen cover, richness, and composition as affected by disturbance origin, time since disturbance, and forest type over 33-year chronosequences in Ontario, Canada. Epiphytic macrolichens were absent 7. years after fire or logging, but their cover and richness thereafter increased with stand age for all overstory types in both fire and logged stand. While macrolichen cover and species richness did not differ in stands ≤15. years old between the two disturbance origins, post-logged stands had lower macrolichen cover in conifer and mixedwood stands, but similar species richness compared with post-fire stands after 33. years. More pronounced was the compositional difference of epiphytic lichens among overstory types, stand ages, and disturbance origins. Our results demonstrate that epiphytic macrolichen cover and richness increase with stand age and logging reduced macrolichen cover compared with fire. Furthermore, logging resulted in epiphytic macrolichen communities different from fire. The differences in macrolichen cover, richness, and composition between logging vs. fire could be attributed to several stand-level differences including initial stand composition, regeneration density, and tree species diversity.