, 1997). Tree retention practices have so far mainly been associated with clear-cutting forestry, and are Selleckchem A-1210477 today applied in North America, Europe and Australia (Gustafsson et al., 2012). Although the practices have been going on for a long time and on a large scale, little is known about potential positive effects on biodiversity. Tree retention has several aims. Structures left at harvest should (1) function as lifeboats by facilitating long-term survival of species from the previous old forest (Franklin et al., 1997), (2) contribute

to a more structurally diverse environment (Franklin et al., 1997), (3) act as stepping stones and thus increase dispersal possibilities of species (Franklin et al., 1997), (4) increase the amounts of old living trees and large dead trees in the early successional forest, and buy Dolutegravir thus be of importance to species adapted to such structures in the initial phases following natural disturbances (Gustafsson et al., 2010), and (5) sustain ecosystem functions like mycorrhiza formation and nitrogen retention (Gustafsson et al., 2010). Most research on biodiversity effects of retaining trees point

to positive responses compared to traditional clear-cutting (Rosenvald and Lõhmus, 2008) although retention levels are often found to be too low to benefit many species groups (Aubry et al., 2009). Deciduous trees are characteristic of intact boreal forest landscapes especially in the early stages of the forest succession (Esseen et al., 1997). One of the most common deciduous tree species is aspen,

present all around the circumpolar boreal forest belt, in Eurasia as Populus tremula L. and in North America as Populus tremuloides Michx. Old deciduous trees are one of the most important habitats for red-listed species in the PAK5 boreal forest ( Berg et al., 1994), and aspen is a hotspot for boreal forest biodiversity in both Eurasia ( Kouki, 2008) and North America ( Campbell and Bartos, 2001). Aspen has increased in frequency in recent years in Sweden ( Hellberg, 2004), mostly due to regeneration on abandoned agricultural land, and a change in forest management actions from clearing to protecting deciduous trees ( Larsson and Thor, 2010). Despite a general increase, aspen is decreasing in protected forests in Northern Europe, and regeneration on forestland is low due to browsing of saplings by moose and a lack of natural disturbances such as fire ( Kouki et al., 2004). Lichens are a species-rich group with more than 2400 species in Sweden (Gärdenfors, 2010). They are symbiotic associations between a fungus and a photobiont (green algae or cyanobacteria) that disperse sexually by fungal spores or by vegetative propagules with both the fungus and the photobiont (Budel and Scheidegger, 2008).