Effects of salvage logging on the soil microclimate of temperate European forests following Norway spruce dieback

In most managed forests, salvage logging is a common method of regaining forest natural and economic capital following disturbances. Nevertheless, trade-offs between management objectives and the ecological impacts of salvage logging can influence other forest restoration decisions. Following an episode of Norway spruce (Picea abies) dieback in 2018, we monitored soil temperature and soil water content, both key soil microclimate variables, to assess the impact of three commonly used post-disturbance treatments: immediate salvage logging (< 2 years), delayed salvage logging (3–4 years), and no salvage logging. Immediate logging had the greatest negative impact on soil temperature variables, with maximum daytime soil temperatures increasing by up to 3.5°C in the topsoil (10 cm) and diurnal temperature variation rising by up to 1.9°C. Increases were also evident in the subsoil layers (30 and 60 cm). Prolonging the time between disturbance and logging, however, mitigated these negative effects on soil temperature stability, providing soil microclimate readings similar to those at sites with no salvage logging and/or pre-disturbance conditions. In addition, delaying salvage logging, or opting for no salvage logging, resulted in an 8–11 % increase in soil water content compared to the control. These findings suggest that postponing salvage logging by approximately 3–4 years significantly reduces negative ecological impacts on soil microclimate and enhances the resilience of temperate forests in the face of potential large-scale disturbances under climate change.