Epiphytic lichen colonization in regenerating black spruce forest stands of clearcut origin

Colonization of young forest stands by epiphytic lichens is an important phenomenon for the maintenance of viable populations of epiphytic lichens in forest landscapes affected by periodic severe disturbances. We examined colonization of epiphytic species in regenerating black spruce stands in boreal forests of western Quebec. The number of thalli of each species were counted on branches sampled on young trees located in recently harvested stands, at different distances from adjacent mature forests (from 5 to 100 m). We sampled stands that were regenerated with two methods: stands that regenerated using advance regeneration that established in the understory before harvest and stands that were regenerated with post-harvest plantations. Lichens were also inventoried in two age classes: between 6 and 10 years and between 12 and 18 years after harvest. The results indicate that for the younger age class, the number of thalli on branches was superior in stands regenerated using advance regeneration for most epiphytic lichen species, whereas the difference between the two types of regeneration disappeared in the older age class. Distance from the adjacent stand had little influence on thalli number for most species, except for Bryoria spp. that disperse mainly through thallus fragments. These results suggest that most lichen species can colonize the microsites present in regenerating stands, independently from regeneration type. However, we underline that this result should be put in perspective because the forest matrix still contains a high proportion of virgin mature stands, and that diaspore sources (and colonization rates) could decline as these mature stands continue to be harvested and replaced by younger stands. (C) 2012 Elsevier B.V. All rights reserved.