The Potential for Long-Term Sustainability in Seminatural Forestry: A Broad Perspective Based on Woodpecker Populations

We assessed ecological sustainability of seminatural forestry by analyzing 80-year dynamics and the current distribution of all woodpecker species in Estonia. We found that, despite the clear-cutting-based forestry system, woodpeckers inhabited commercial seminatural forests in substantial numbers, including the species generally considered vulnerable to timber harvesting. The only negative trend, a drastic decline in the Green Woodpecker, paralleled the loss of seminatural, wooded grasslands and is mostly an issue for landscape planning and agricultural land use. Major silvicultural factors supporting other species in commercial forests include natural regeneration with multiple native tree species and deadwood abundance. In such context, the main role of protected areas is to provide ecological resilience; however, we estimated that the current strict reserves could further double their carrying capacities for woodpeckers through successional recovery and, perhaps, active restoration. The long time series used were instrumental in detecting unexpected dynamics and the impacts of climatically extreme years. We conclude that (1) seminatural forestry can serve as a basis for reconciling timber harvesting and biodiversity protection at the landscape scale, given appropriate attention to key structures and landscape zoning and (2) woodpeckers represent a biological indicator system for the sustainability of forest landscapes in Europe.