The retained aspen might also be easier to colonize by
wind dispersed spores simply because the surrounding forest that previously could have been a physical obstacle to dispersal now is removed. In the ISA we found 36 species to be characteristic of young forest. From information on lichen species ecology in the literature and our own field experience, we propose that Caloplaca cerina, C. flavorubescens, C. holocarpa, C. jemtlandica, Leptogium saturninum, Melanelia exasperata, Phaeophyscia ciliata, Physcia aipolia, P. tenella, Rinodina septentrionalis and Xanthoria parietina, all aspen specialists, were present in the old forest, but then higher up or in the crown, and had after logging migrated downwards. On SCH 900776 mw the other hand, the generalist species Bryoria spp., Catinaria atropurpurea, Cladonia coniocraea, C. fimbriata, Hypogymnia physodes, Lecanora expallens, L. circumborealis, L. pulicaris, PI3K inhibitor L. symmicta, Lecidea nylanderi, Ochrolechia androgyna, Parmeliopsis ambigua, P. hyperopta, Tuckermanopsis chlorophylla, Usnea
spp. and Vulpicida pinastri are probably new on the aspens, but could have existed in the forest on other tree species. Lecidea albofuscesens was the only species that indicated clearcuts, i.e. old forest. This species is known to grow in shady and moist environments (F. Jonsson, personal observation), and is evidently sensitive to the exposure after logging ( see Appendix for more details). We found 195 species, which was more than twice as much as we expected based on earlier reports. Another published study on the complete lichen flora (foliose, fruticose and crustose species) on aspens
trees was performed by Ellis and Coppins (2007) who found 273 species in 93 aspen stands in Scotland. Although the importance of aspen for lichen biodiversity has been emphasized earlier (e.g. Kuusinen, 1996 and Kouki et al., Amoxicillin 2004), our study clearly demonstrates the great diversity of the lichen community connected to aspen in boreal Northern Europe. Despite the high number of recorded species (85% of the regional species pool), new species should have been added successively with increasing sampling effort, and among these very likely a number of rare, red-listed ones. On the Red List for the counties of Västernorrland and Jämtland, where the study was conducted, there are 30 lichen species that could grow on aspen (Gärdenfors, 2010), i.e. 19 more than we found in our study. Aspens retained at harvest have a great potential to enrich future forest landscapes and to contribute to the persistence of biodiversity connected to this habitat. We found red-listed lichen species also in the young forest, and the total species richness was even higher on the aspens exposed for 10–16 years. This indicates that opening up of stands with aspens could be a positive conservation management action, for instance in connection with thinnings, but also in protected forests.