Age structure and disturbance dynamics of the relic virgin beech forest Uholka (Ukrainian Carpathians)

The Carpathian mountains harbour the largest areas of virgin European beech (Fagus sylvatica L.) forest. Understanding the growth dynamics of European beech under natural conditions without human intervention is crucial for close-to-nature management of beech forests in Europe. In this study we give an insight into the natural disturbance dynamics of the virgin beech forest Uholka, based on a structural analysis and a dendroecological reconstruction of its history. On four circular plots of 0.1 ha each, DBH and tree height of all living trees ⩾6 cm DBH were measured. Increment cores of all the 164 trees were taken for age estimation and growth pattern analysis. To identify significant growth releases and reconstruct the disturbance history a dendroecological approach, referred to as the boundary line method, was employed. The density of the living trees per plot ranged from 270 to 590 stems per ha and the volume from 525 to 1237 m3 per ha. The longest tree-ring series was 451 years long, however age estimation methods showed that beech could reach an age of up to 550 years. All four plots covered an age span of at least 300 years and can be characterised as uneven-aged with continuous tree establishment. Beech can survive long suppression periods of over 100 years and shows regularly distributed growth releases over the analysed period (1870–1999). The results suggest that stand dynamics in this forest are driven by periodic small disturbances, while larger events occur only rarely. The high percentage of rotten trees in the upper canopy indicates that individual trees are prone to windbreakage, which promotes these small-scale dynamics.

► We analysed the age structure of a virgin beech forest based on 164 increment cores.
► Beech can reach ages of up to 500 years, although old trees are prone to stem rot.
► Beech can survive long suppression periods of more than 100 years.
► Small-scale disturbances lead to continuous tree recruitment and structural diversity.