Assessing impacts of intensified biomass removal on deadwood in European forests

Deadwood is a key indicator for assessing policy and management impacts on forest biodiversity. We developed an approach to include deadwood in the large-scale European Forest Information Scenario (EFISCEN) model and analysed impacts of intensifying forest biomass removal on the amount and type of deadwood in forests of 24 European Union member states. In EFISCEN, deadwood consists of standing and downed deadwood, resulting from mortality, and stem residues from felling activities. To include deadwood in EFISCEN we developed mortality functions and re-estimated the model's increment functions. Further, we modelled the development of standing deadwood. Decomposition of downed deadwood and stem residues was modelled through the soil model YASSO. We used the extended model to analyse the impacts of a baseline scenario (no policy changes, a moderate increase in wood removals and no extraction of residues) and a bio-energy scenario (an increase of wood and residue removals to the maximum potential) on deadwood in 2030. In our baseline scenario the average amount of deadwood was 12.3 ton ha−1 in 2005 and increased by 6.4% in 2030. Intensified biomass removal could fully counteract this development and lead to a reduction of 5.5% in 2030 below the levels in 2005. The type of deadwood changed as well; residue removal led to a general decrease in the amount of smaller deadwood fractions (i.e. stem residues). Further, if felling levels are increased as in our bio-energy scenario, a decrease can be expected in the amount of standing deadwood and of large-diameter deadwood. We conclude that without additional management measures to protect deadwood, intensification of biomass removal could negatively affect deadwood-dependent species, which constitute an important part of biodiversity in European forests.