Environmental drivers of bryophyte distribution and habitat preference in <i>Sphagnum </i>peatlands of Eastern Canada

The concept of habitat niche describes species distribution, aids in analyzing community structure, function, and diversity in changing environments, and guides peatland restoration and conservation efforts. Information on peatland sedges and bryophytes is available for Western Canada, but the habitat niche of peatland bryophytes is minimally described in Eastern Canada. Using data from 1403 quadrats in 168 Sphagnum-dominated peatlands across three climatic regions, the habitat preferences of dominant bryophytes were characterized along several environmental gradients. Sphagnum magellanicum complex, S. capillifolium and S. fuscum were the most widespread bryophytes in the studied peatlands in terms of frequency, and when present, S. rubellum dominated coverage. Bryophyte species distribution is mainly controlled by water surface chemistry (pH, K, Na, Ca, SO 4 -2 , Al, Fe), macroclimatic conditions (total rain, seasonal aridity index, biotemperature) and shading by vascular plants. Seven ecological groups were identified with hierarchical clustering, pooling 37 bryophytes, 38 vascular plants and three ground covers (bare peat, litter, open water). Tree and lichen abundance were the main variables differing in Sphagnum-dominated peatlands across climatic regions in Eastern Canada. This understanding aids in preserving and restoring vital ecosystems, guiding informed decisions and proactive measures to mitigate climate change impacts on biodiversity and ecosystem functioning.