Replication Data for: Changing species dominance patterns of Boreal-Arctic heathlands: evidence of biotic homogenization

This dataset contain coverage of vascular plants in plots from a range of sites in northern Fennoscandia. Main findings are presented in the following abstract: Heathlands are extensive systems often dominated by slow-growing and long-lived woody plants. These systems require longer-term studies to capture if and how they are changing over time. In 2020, we resurveyed species richness and cover of vascular plant communities in 139 heathlands along the coastline of northern Fennoscandia, first surveyed during 1965-1975. The first survey included six heathland types, each with dominance – a cover of 25% or more – of the dwarf shrubs Calluna vulgaris, Kalmia procumbens, Betula nana, Vaccinium myrtillus and Empetrum nigrum. The two latter heathland types made up 29% and 48% of all heathlands respectively. In addition to the dominant dwarf shrubs giving name to the heathland types, a few other species qualified as dominant. In the resurvey all the heathland types had Empetrum nigrum as the single dominant species except for the heathland formerly dominated by Betula nana. Most other species had low cover both at the time of the original survey and the resurvey. Also, the heathland types were species poor at the time of the original survey, with an average of eight vascular plant species per 4m2 and were found equally species poor in the resurvey. Species richness differed between heathland types only at the time of the original survey, and the ratio of species exchange between the two surveys was negatively related to the original cover of Empetrum nigrum. Here we provide a half-century perspective on vegetation change, during which several heathland types in northern Fennoscandia have changed to Empetrum-heathlands, reducing the diversity of heathland types across the Boreal to Arctic landscape. As a native plant, Empetrum nigrum cannot be considered invasive, but its allelopathic capacity has likely already modified these heathland ecosystems and will continue to do so, reducing ecosystem multifunctionality across the region.