Vegetation dynamics 1946–2018 in an old-growth conifer forest

We analysed ground vegetation in 250 plots in 2018 in the old-growth Picea abies-dominated forest Säby Västerskog, SE Sweden as a follow-up of studies in 1946 and 1998 with the same layout of plots. The vegetation changes were not clearly directional: the species composition in 2018 was intermediate between that of 1946 and 1998, whereas in 1998 species richness was higher and with the unique presence of a number of species indicating small-scale disturbances. Vaccinium myrtillus increased in cover since 1946 and Avenella flexuosa decreased. This goes against regional trends, attributed to climate warming and changes in nitrogen deposition. Regional changes are overshadowed by fine-scale disturbances and micro-successions.

Methods
We analysed ground vegetation in 250 plots in 2018 in the old-growth Picea abies-dominated forest Säby Västerskog, SE Sweden as a follow-up of studies in 1946 and 1998 with the same layout of plots.

The plots were not  permanently marked but their position is recorded with GPS coordinates to make it possible to repeat the study. Plot size was 0.5 m2 in 1946, but changed to 1 m2 in 1998 and 2018. Cover was recorded in the Hult-Sernander-Du Rietz scale.

Vegetation changes were analysed by ordination and similarity in species composition. For a subset of species the cover changes are shown in maps for the three surveys.