Epiphytic lichens are important species in the forest ecosystem. The Swedish forestry model affects them by fragmenting large old continuous forests. These fragments could be used as islands in a test of MacArthur and Wilsons theory of island biogeography. This study investigates if island biogeographic factors such as area and distance from nearest continuous forest affects lichen diversity in forest fragments, In addition time since logging to investigate if the populations will reach equilibrium and also if differences in habitats such as forest volume affects lichen diversity in addition to island biogeography. The number of lichen species were examined in 15 boreal forest fragments north of Storuman municipality, Västerbotten.
According to the results, positive significant correlations were observed between the number of lichen species and island biogeographic variables in the area of the islands. No positive correlations could be observed between the number of lichen species and distance to the nearest continuous forest. There were also significant correlations between number of species and time since logging around the forest islands. However, there were positive correlations between the number of lichen species and forest volume, which tells us that more than island biogeographic factors that affect lichens in the form of habitat changes. This study indicates that in order to favor lichen diversity in forest landscapes it is important to maintain larger forest fragments with older trees. Clearly forest management agencies should consider the complex ecology of lichens when planning and performing forestry practices.