Occurrence of epiphytic macrolichens in relation to tree species and age in managed boreal forest

For the maintenance of biodiversity some epiphytic macrolichens have been u sed to identify forests with high conservation value, To understand what th ese macrolichens indicate, we studied the relationships of tree species and age with the abundance of a jet of 33 macrolichens (20 of them in use as i ndicator species) at 90 localities in a 150 km(2) area in south-central Swe den. We sampled the four most common tree species Scots pine Pinus sylvestris, N orway spruce Picea abies, birch Betula spp. and aspen Populus tremula for m acrolichens at 0-2 m from the base. Of the 33 target species we found 17, s ix of them were indicators in use for this region. In 30, out of 40 tested, cases there was a positive relation between lichen abundance and age of th e tree. On all tree species the number of the studied lichen species increased with age. The colonisation rate of the species was fastest on birch. All specie s occurring on birch were also found on at least one of the coniferous tree s. while aspen had six species nor found on other trees. Pine and spruce wi th a slow growth rate had more signal lichen species than fast growing tree s. We could not detect a competitive situation between common and rare species as the most abundant or largest lichens did not exclude other species, The length of the longest fruticose lichen was positively correlated with the number of species on the tree. Shade had a negative effect on the number of species. We conclude that the indicator macrolichens encountered in this Study showe d a preference for old trees or aspens. This result, and the low number of indicator species, points at the importance of promoting these trees for th e preservation of biodiversity in the boreal forest.