In our paper ‘Self-facilitation and negative species interactions could drive microscale vegetation mosaic in a floating fen' we analyze the spatial distribution of poor and rich fen mosaic in a floating fen in Connemara, Ireland. Two distinct vegetation types were identified, Scorpidio-Caricetum diandrae (rich fen) and Erico-Sphagnetum magellanici (poor fen), of which we selected three vegetation plots: rich fen (n=3), poor fen (n=4) and poor fen patches within rich fen vegetation (n=3). In all plots we measured biogeochemical variables at different depths (+5, -10 and -50 cm). Next to that, geohydrological measurements were conducted in the floating fen. We found that geohydrological conditions likely drives the distribution of poor and rich fen species at a larger scale in the floating fen, due to the supply of minerotrophic groundwater. Interestingly, both poor and rich fen vegetation occurred in a mosaic, when electrical conductivity values at 50 cm depth were between 300 and 450 µS cm-1. Although environmental conditions were homogeneous at 50 cm, they differed markedly between rich and poor fen vegetation at 10 cm depth. Specifically, our measurements indicate that poor fen vegetation lowered porewater alkalinity, bicarbonate concentrations and pH. No effects of rich fen vegetation at 10 cm depth on biogeochemistry was measured. However, rich fen litter had a higher mineralization rate than poor fen litter, which increases the influence of minerotrophic water in rich fen habitat. These results strengthen our hypothesis that species can drive formation of vegetation mosaics under environmentally homogeneous conditions in a floating fen with positive intraspecific self-facilitating mechanisms and negative species interactions.

The data can be found in the following files, containing primary data: - VanBergen_etal_2019_primary_data_geohydrology - VanBergen_etal_2019_primary_data_biogeochemistry - VanBergen_etal_2019_primary_data_aerobic_mineralization