Patterns and determinants of lichen abundance and diversity across a subarctic to arctic latitudinal gradient

Abstract Aim Lichens are a major component of Arctic biodiversity. However, they appear vulnerable to climate change, as they are exposed to warmer temperatures and increased competition with vascular plants. Our study aims to evaluate lichen cover, species richness, functional diversity and community composition among the dominant vegetation types along a 640‐km latitudinal gradient, and to identify environmental determinants related to patterns in lichen communities. Location From subarctic (56°N) to arctic (62°N) Nunavik (Québec, Canada). Taxon Lichens. Methods We characterized macrolichen communities at the species level in 42 sites across a latitudinal gradient, and identified latitudinal trends in lichen cover, species richness and functional diversity. Using linear models and distance‐based redundancy analysis, we investigated the effect of climate, vegetation, topography and soil characteristics on lichen communities. Results Lichen cover and species richness were the lowest at high latitudes, while functional diversity increased with increasing latitude. Vegetation types and surficial deposits were strongly related to lichen cover and richness. However, these factors did not influence functional diversity, which was mainly driven by climatic conditions. Main conclusion Our results highlight the importance of vegetation structure in lichen communities and corroborate the negative relationship between vascular plant abundance and lichen abundance and species richness. While we found no influence of vegetation structure on lichen functional diversity, further studies using targeted functional traits are needed to accurately investigate the impact of ongoing changes in northern vegetation on ecosystem functioning.