Om att bryta ihop och komma igen – skogsdynamik i Dalby Söderskog 1935-2019

This study aimed to quantify long-term dynamics in the 37-ha forest reserve Dalby Söderskog in southern Sweden during the period 1935–2019. Data from five vegetation surveys showed dramatic changes in the tree and shrub layers. An increasing dominance of Ulmus glabra during the first 50 years was broken by high tree mortality due to Dutch elm disease Ophiostoma novoulmi. Instead, Fraxinus excelsior gained dominance but is now heavily affected by ash dieback Hymenoscyphus fraxineus. This has left Fagus sylvatica as the most important canopy tree species, but long-term effects of Phytophthora species may become increasingly troublesome for beech. The opening of the canopy due to tree mortality from fungal diseases has created suitable conditions at the forest floor for regeneration of more light-demanding species, in particular Quercus robur, Corylus avellana and Crataegus spp., thereby moving the forest composition back towards a state prior to protection more than 100 years ago.