2020

Peura, Maiju

More sustainable silvicultural approaches are needed to stop the loss of biodiversity and ecosystem services. Most boreal forests are managed with rotation forestry, and continuous cover forestry has been suggested to be a method to reduce the negative impacts of forestry on nature. In the thesis, I studied the impacts of continuous cover forestry on biodiversity and ecosystem services in boreal forests in Finland. I used long-term forest simulations in commercial forest landscapes and empirical methods in streamside key habitats. Simulations showed that continuous cover forestry could be a cost-efficient method to retain ecosystem services and, for example, habitats of species dependent on deciduous trees or mature forest structure. However, at the landscape scale, diverse use of regimes from both continuous cover forestry and rotation forestry was the best in terms of both biodiversity and ecosystem services. Moreover, the amount of dead wood was low in both silvicultural approaches. Empirical studies, on the other hand, showed that the selective loggings of continuous cover forestry disturbed the natural features in streamside key habitats and therefore are not a sustainable method to manage these habitats. The area of unmanaged forests needs to be increased to stop the biodiversity decline. Scenario simulations revealed that from both ecological and economic perspectives, it could be effective to allocate strict protection and conservation measures in commercial stands jointly into specific landscapes. Together, the studies of my thesis suggest that increasing the share of continuous cover forestry in commercial forest landscapes could alleviate the negative impacts of forestry on biodiversity and ecosystem services. However, more protection, careful landscape-scale planning, and retention of essential biodiversity features, such as dead wood or key habitats, are still needed irrespective of the silvicultural approach. Moreover, both rotation forestry and continuous cover forestry can be done more or less intensively. Therefore, instead of strongly contrasting the approaches, more attention should be paid into the amount of harvested timber in commercial forests.