*2.1. Study Area*

The study was carried out in the Janj (44◦08 N, 17◦16 E) and Lom (44◦27 N, 16◦27 E) old-growth forests in Bosnia and Herzegovina. Both forests are classified as forest association *Piceo-Abieti-Fagetum dinaricum*, and include a mixture of European beech (*Fagus sylvatica* L.), silver fir (*Abies alba* Mill.), and Norway spruce (*Picea abies* (L.) H. Karst) with a negligible share of other species [30]. These forests are located in the central part of the Dinaric Mountains in south-east Europe, approximately 90 km from the Adriatic Sea. The Norway spruce in this region is considered to be an endangered species due to climate warming [31], while the silver fir seems to be less vulnerable [30]. The investigated old-growth forests are situated in an altitudinal belt between 1260 and 1400 m above sea level. The mean annual temperature in the study area is around 5 ◦C, and the annual precipitation ranges between 1400 and 1900 mm. The bedrock is composed of dolomite and limestone in Janj and Lom, respectively, while brown soils prevail in both forests. Considering the high levels of live and dead wood [23,30] and the long history of forest protection [32,33], the core areas of Janj and Lom rank among the best-preserved old-growth forests in Europe. In addition, the core areas of Janj (57.2 ha) and Lom (55.8 ha) are surrounded by relatively large buffer zones (237.8 ha and 297.8 ha, respectively) in which only low-intensity salvage cutting has been performed.
