Importance of Forest Act habitats for epiphytic lichens in Finnish managed forests

Habitats of particular importance, as defined in the recent Forest Act of Finland, provide a new means to conserve forest biodiversity in managed forest landscapes. These “Forest Act habitats” should by definition contain populations of rare and red-listed species, but their species composition has not been studied. In this work, indicator and red-listed lichens were studied in private forests of southern Finland in three Forest Act habitat types (brookside forests, herb-rich forests, cliff-forests). Threatened species were found only in 9%, red-listed species in 29% and indicator species in 50% of the study sites. Populations of the target species were mainly very small, half of them on no more than one tree, and thus prone to extinction. Picea abies, Populus tremula and Sorbus aucuparia were the most important host tree species for indicator lichens. The Forest Act habitats appear to make only a limited contribution to the conservation of indicator and red-listed lichens. This is because delimited Forest Act habitats are small-sized sites and rarely harbour old forest stands. Moreover, even selective logging and felling of individual trees, which are generally permitted in Forest Act habitats, can decrease the persistence of epiphytic lichens. Thus, the biodiversity goals integrated in the Forest Act appear to be incompletely realized in current forestry practices.