%0 Articles %T Retention forestry and intensified biomass harvest: epiphytic lichen assemblages under opposing ecological effects in pine-dominated boreal forests %A Hämäläinen, Aino %D 2016 %J Dissertationes Forestales %V 2016 %N 218 %R doi:10.14214/df.218 %U http://dissertationesforestales.fi/article/2002 %X Intensive forestry has led to changes in the structure and function of boreal forests and to the endangerment of forest-dwelling species. Different management methods, such as retention forestry, have been developed to counter the negative biodiversity impacts, although forest use has intensified at the same time: for example, stumps and logging residues are commonly harvested for biofuel. This thesis examines the potential impacts of biofuel harvest, retention forestry and prescribed burning on epiphytic lichen assemblages in pine-dominated boreal forests. In addition, post-harvest dynamics of retention trees were studied to assess their capacity to support species diversity in the early successional forests. The study is based on a large, empirical dataset collected in eastern Finland from 24 study sites that were treated experimentally with a combination of retention harvest and prescribed burning, and, additionally, from 13 sites that represent different stages of forest succession. The results show that retention forestry has the potential to maintain pre-harvest legacies and support high lichen diversity on harvested sites: 85 lichen species, including Red-Listed species and dead wood specialists, were recorded on retained Scots pines (Pinus sylvestris L.) or their dead wood legacies 11 years post-harvest. However, the outcome of retention forestry is affected by post-harvest mortality rates and the fall patterns of the retained trees, which in turn differ depending on the retention tree volume, possible application of prescribed burning, and tree-level factors. Prescribed burning of harvested sites increased retention tree mortality rates and decreased epiphytic lichen richness 11–12 years post-fire. However, in combination with high retention volumes, burning created more diverse dead wood habitats than retention forestry alone. Thus, despite the initial negative effect, the application of prescribed burning on part of the harvested sites could eventually increase lichen diversity at the landscape scale. Scots pine stumps on harvested sites hosted 83 lichen species, and may be a valuable habitat resource for wood-dwelling lichens if dead wood volumes in the landscape are otherwise low. Therefore, large-scale stump harvest may decrease lichen diversity. Instead, fine woody debris was found to be a less valuable substrate for epiphytic lichens and could be harvested for biofuel without notable effects on lichen populations. This study shows that retention forestry can be used to enhance lichen species richness in managed forests, while stump harvest has the opposite effect by reducing lichens’ habitats. Prescribed burning decreases lichen species richness at the stand scale but may enhance it at the landscape scale, provided that burning is avoided on the most valuable, lichen-rich stands.