Sweden is an ideal case for such an analysis since the retention approach has been practiced in this country for more than two decades (Eckerberg, 1988, Götmark et al., 2009 and Gustafsson and Perhans, 2010), and an extensive and high-quality National Forest Inventory data-base exists that can be used for detailed analysis. Due to a long history of industrial forestry in North Europe, and especially in Sweden and Finland, production forests have become more even-aged and much less structurally diverse than intact forests. Amounts of dead wood, old trees and other properties of importance to biodiversity are much lower

compared with natural forest landscapes (Fridman Natural Product Library and Walheim, 2000, Peterken, 2001 and Josefsson and Östlund, 2011). The importance of incorporating old-growth elements in managed forests is increasingly being recognized

(e.g. Bauhus et al., 2009), and dead trees and old living trees are known to be of large importance to biodiversity, not the least to threatened species (e.g. Bernes, BIBF1120 2011). A multiscale model for forest conservation is applied in Sweden, implying that conservation actions are taken at different scale-levels from individual trees to areas embracing hundreds or thousands of ha. The highest level, up to 1000 ha or more, includes formally protected areas such as national parks and nature reserves. At the next, intermediate level (ca. 1–50 ha) there are both formally protected and voluntary set-asides through certification, many many of which are so called woodland key habitats (Timonen et al., 2010). Retention approaches represent the lowest scale level, implying that trees of importance to biodiversity and ecosystem function

are left unlogged, mainly at final felling operations, but also during thinning. Single living trees are retained, and tree patches may be left as ‘islands’ in felled areas or adjacent to non-felled stands, often as buffer strips along lakes, rivers, wetlands and near settlements. Standing and lying dead trees are also retained, and according to instructions they should not be harmed during logging operations. Dead wood is created, in Sweden primarily through artificially creating snags by cutting trees at a height of 3–4 m, but also by retaining living trees of which some or many will eventually become windthrown. The state is responsible for establishing nature reserves, while both the state and the forest owners protect also smaller areas. Retention requirements have been part of Swedish forest legislation since the 1970s, and were made well-known to landowners through the “Richer Forest” campaign by the Swedish Forest Agency in the beginning of the 1990s. They were further consolidated with the launch of a new forest policy in the mid 1990s in which environmental and production goals were assigned equal value (Bush, 2010).