Large-scale forest disturbance and associated management shape bird communities in Central European spruce forests

In Central Europe, natural forest disturbance is increasing due to climate change and the legacies of past forest management. The resulting early successional forest stages shape habitat conditions and availability for forest-dwelling species. How disturbance, pre-disturbance forest management such as beech underplanting in conifer stands and post-disturbance management, such as salvage logging, shape biodiversity is poorly understood. In a large field study, we quantified how the large-scale loss of mature spruce plantations after natural disturbance affects bird diversity and abundance in Central Europe and how this is moderated by pre- and post- disturbance management. In a Bayesian community distance sampling approach, we conducted field surveys on 182 plots in a stratified design, comparing bark beetle and windthrow disturbances as well as two management treatments, (i) underplanting with beech before the disturbance occurred versus no underplanting and (ii) salvage logging versus no post-disturbance logging. We used undisturbed mature spruce plantations as a control. Bird diversity was higher in disturbed forests than in undisturbed spruce plantations and was affected little by management. Bayesian community distance sampling models revealed that responses were highly species-specific: shrub-associated birds profited from disturbance in general and reached highest densities where beech had been planted under the spruce canopy before the disturbance occurred, whereas open-habitat and farmland birds reached higher densities on salvage-logged sites. Only few typical species of coniferous forests persisted at disturbed sites. Synthesis and applications. With increasing forest disturbance, pre- and post-disturbance management can promote target bird species. Shrub-associated species can be promoted by underplanting, open habitat-adapted species by salvage logging and species depending on vertical structures by no intervention. For maximising biodiversity benefits at a landscape scale, underrepresented management practices (no intervention) should be promoted to ensure a balanced forest management and to maintain diverse post-disturbance bird communities.