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Downed and standing deadwood (DW) is a key resource for maintaining forest biodiversity. Although extreme events such as windthrow and fires produce large quantities of DW, this substrate is often drastically reduced by logging activities. To elucidate the respecting consequences of salvage-logging, we assessed both quantity and quality of storm-derived DW (storms Vivian 1990 and Lothar 1999) in Swiss forests using a sample of 90 windthrow sites with C3 ha complete windthrow and at elevations ranging from 350 to 1,800 m a.s.l. The majority had been salvage-logged (SL) a few years after the windthrow. On each site, we recorded DW amount and quality on six circular sample plots 20 or 50 m 2 in size. DW volume on SL sites was surprisingly high, with 76.4 m 3 ha -1 on average 20 years after Vivian and 73.8 m 3 ha -1 10 years after Lothar. In comparison, DW volumes on unsalvaged sites, that is, with no post-windthrow intervention (NI), amounted to 270 m 3 ha -1 . A wide variety of wood decay stages and diameter classes (10 to C70 cm) was found on both NI and SL sites, suggesting considerable habitat diversity for DW-associated species irrespective of the treatment. The considerable amounts of DW left after salvage-logging distinctly exceed the minimum DW volumes in forest stands proposed by Müller and Bütler (Eur J For Res 129: 981-992, 2010) in a conservation context, which demonstrates the importance of wind disturbance for biodiversity. Further studies should quantify DW of individual tree species, since habitat requirements are speciesspecific.

Stand structures and stand stability in unmanaged Norway spruce forests in the Swiss mountains may decline and their protective function against natural hazards will thus be put at risk. They are being subjected to thinning operations to improve stability and, in the long-term, to transform them into mountain selection forests. On pairs of research plots – thinned and not thinned – we will closely follow the stand development. Preliminary results indicate that the best variables to describe the effectiveness of the applied treatment to the stand structures are the h/d ratio,the spatial distribution and the stand density index.

Two different selection forest stands not in their state of equilibrium are investigated and discussed with regard to the changes in selected structural parameters, the influence of site factors and management.