Vegetation of open habitats in the Turku Archipelago (Finland): the GrassPlot dataset Fl_A sampled during the 21st EDGG Field Workshop

The 21st Field Workshop of the Eurasian Dry Grassland Group (EDGG) was conducted from 28 June to 6 July 2025 in the Turku Archipelago, Finland, and was the first Field Workshop ever held in Northern Europe. The research expedition aimed to survey the diver-sity of semi-natural pastures and meadows, rocky dry grasslands, sandy grasslands, coastal habitats, wooded pastures, heathlands, and wetlands in the region, focusing on vascular plants, bryophytes, and lichens. In total, we sampled 170 nested-plot series from 1 cm2 to 10 m2, and for a subset of 38 plots extended sampling to a seventh grain size of 100 m² (full “EDGG Biodiversity Plots”). Mean species rich-ness ranged from 2.9 species in 1 cm² to 51.6 species in 100 m², with bryophytes and lichens contributing increasingly higher fractions at larger grain sizes. Plots were preliminarily assigned to 14 vegetation classes, namely the Cakiletea maritimae, Calluno-Ulicetea, Festuco-Brometea, Honckenyo-Elymetea, Juncetea maritimi, Koelerio-Corynephoretea, Molinio-Arrhenatheretea, Nardetea strictae, Oxycocco-Sphagnetea, Phragmito-Magnocaricetea, Polygono-Poetea, Scheuchzerio-Caricetea, Sedo-Scleranthetea, and Trifolio-Geranietea. The collected plots can serve as a baseline for long-term monitoring; the final dataset will be integrated into GrassPlot (ID: FI_A), EVA and sPlot.