The tragedy of the science-policy gap - Revised legislation fails to protect an endangered species in a managed boreal landscape

Unsustainable use of forest resources poses a serious threat to biodiversity worldwide. This threat is particularly important in boreal biomes, where intensive production-oriented forestry is widely applied. Legislation is one of the key tools for preserving nature from anthropogenic damage. Designation of environmental legislation should be grounded on sound scientific evidence in order to be effective. We assess the impact of guidelines enforcing the Finnish ad-hoc legislation aimed at preserving breeding sites and resting places of the Siberian flying squirrel (Pteromys volans), a protected species in Finland and in the European Union under the Habitats Directive. Its habitat is under pressure from widespread forest clear-cutting practices. We collected data on site occupancy by breeding female flying squirrels from 81 sites spanning 12 years (2005-2016) and on relevant habitat variables around the site. Using generalized linear mixed models we quantified the predicted occupancy of breeding female flying squirrels in relation to the cover of breeding habitat around a site. We then compared the resulting habitat requirements of breeding females with the habitat that would be retained according to the initial national legislation guidelines and their proposed first revision. We show that both the initial and the proposed revision of the habitat protection guidelines allow the retention of breeding habitat patches of minimal size, which would yield a very low (less than 5%) predicted occupancy by a breeding flying squirrel female. The current revised guidelines are not science-driven and remain ineffective in safeguarding the species habitat from expanding forestry. These results expose the wide gap between science and policy for the implementation of environmental legislation, in this case the Habitats Directive, to protect species of conservation concern. There is an urgent need to fill the science-policy gap in order to achieve the preservation of biodiversity in a world under rapid transformation.