Effects of forest management on epiphytic lichens in temperate deciduous forests of Europe – A review

This review aims at summarizing literature on epiphytic lichens in relation with forest management in temperate deciduous forests of Europe, including suggestions for mitigating the impact of forestry and stimulating further research. The review is focused on environmental factors that directly depend on, or that are known to interact with forest management, such as tree (and forest) age and size, tree species composition, large scale factors (e.g. climate and air pollution), landscape context, and past forest history. The literature demonstrates the sensitiveness of epiphytic lichens to forestry: forest management, and especially the shelterwood system, is a source of threat for many forest-dwelling lichens. Several studies include explicit recommendations for mitigating the effect of forestry. The main ones are: (a) selective cutting should be preferred to the shelterwood system; (b) the negative effect of the shelterwood system could be mitigated by the extension of the rotation period and by the retention of groups of mature trees at the final harvest; (c) the creation of stands with intermediate canopy openness should be promoted; (d) logs and snags should be retained in production forests; (e) large old trees should be maintained in production forests and some of them left until dead and decomposed (“eternity trees”); (f) tree species diversity should be maintained in mixed stands; (g) forest fragments around existing species-rich oldgrowth remnants should be maintained, to create a network of set-aside areas; (h) indicator species could be used for a rapid assessment of forest sites worthy of conservation. However, some topics are still scarcely explored, such as the case of (a) coppice forests, (b) the evaluation of the landscape context and forest history, (c) dead wood-dwelling communities and the role of different types of dead wood for lichen conservation, (d) the effects of emerging infectious diseases, and (e) the use of indicator species to assess the conservation importance of forests. Other research approaches, that are still scarcely developed for lichens, may contribute further information for a more comprehensive understanding of the processes that are behind observed patterns of lichen diversity, such in the case of the evaluation of the role of species functional traits in determining the dispersal ability and the response of lichens to environmental factors.