Establishment success of lichen diaspores in young and old boreal rainforests: a comparison between Lobaria pulmonaria and L. scrobiculata

This study compares the success of vegetative diaspore establishment of the old forest lichens Lobaria pulmonaria and L. scrobiculata sown on Picea abies branches in boreal rainforests. The larger diaspores of L. pulmonaria (green algal photobiont) established more successfully, and showed a greater flexibility in ecological amplitude, than the smaller diaspores of L. scrobiculata (cyanobacterial photobiont). The establishment success apparently depended on species-specific differences in morphological and physiological traits of the diaspores. Both species established as well in young plantations as in old forests. Lobaria scrobiculata was most successful on short branches and small trees. In contrast, L. pulmonaria responded positively to trunk circumference in the old stands. The establishment success of both species decreases with increasing canopy openness, indicating that the soredia/isidioid soredia failed to establish on the most exposed branches. The probability of establishment did not change with bark-pH or with distance from the nearest stream. Despite a successful establishment in regeneration forests, the long-term survival in managed forests is still uncertain.