The GrassPlot dataset EU-R sampled during the 18th EDGG Field Workshop 2024 in the south-western inner-alpine valleys in France and Italy

The 18th Field Workshop of the Eurasian Dry Grassland Group (EDGG) was conducted from 1 to 11 June 2024 in the inner-alpine valleys of the south-western Alps in France and Italy. The Field Workshop was a continuation of a series of Field Workshops in the inneralpine valleys, using the standardised EDGG sampling methodology. The focus of the workshop was to survey the diversity of Festuco-Brometea and Sedo-Sclerantethea communities in the region including vascular plants, bryophytes, and lichens to fill data gaps for an up-to-date syntaxonomic classification of the inner-alpine dry grassland vegetation. The sampling campaign resulted in an extensive dataset, containing 241 10-m2 plots with 86 of them nested in 43 EDGG Biodiversity plots (nested plots of 0.0001 to 100 (-1000) m2). The dataset will be included in the GrassPlot database as dataset EU-R. The sampled plots were distributed across seven valleys in 36 municipalities and along an elevation gradient from 413 to 1860 m a.s.l. with a mean elevation of 1040 m a.s.l. As a first analysis, the mean vascular plant species richness at 10 m2 was 33.3 without significant differences between the valleys and ranged between 9 to 63. These values resemble those reported from previous Field Workshops in the inner-alpine valleys but are consistently lower compared to other Festuco-Brometea communities outside the Alps. We propose that the dataset presented in this report will contribute to explaining this pattern and to update the syntaxonomic classification of the dry grasslands of the European Alps.