Lichen communities across a subarctic region of Northern Quebec (Canada): conservation status, α- and β-diversity, and functional traits

Abstract

Conservation of lichens is impeded by knowledge gaps on their distribution and habitat requirements. This is a significant issue in vast, isolated and harsh environment regions such as subarctic regions, where lichen communities remain under documented. Lichen biodiversity assessments provide useful insights to better understand the functions supported by these ecologically important and sensitive species. This study aims i) to describe the conservation status of lichen communities and their α- and β-diversity components across a subarctic region in Northern Quebec (190 km2), ii) to describe their functional traits across the habitat types found in this region, and iii) to identify habitat types constituting lichen biodiversity hotspots. Lichens were sampled in 45 plots in habitats ranging from coniferous and deciduous forests to bogs, fens and rocky outcrops. A total of 115 species of largely macrolichens, calicioid lichens and allied fungi were identified, of which 18% currently have ranks of conservation concern at the provincial level, and 38% are newly reported for the region (~124,000 km2 around our study area). Richness across plots averaged 36 ± 9 species and plots richer in microhabitats often harbored more species (R2 = 0.22). Differences in species composition were identified among plots and habitat types through NMDS and perMANOVA analyses (R2 = 0.35; p < 0.001), both being supported by differences in microhabitat composition (Mantel r = 0.22 and perMANOVA R2 = 0.29, respectively; p < 0.001). Thirty-five species showed significant preferences for a habitat based on the Pearson’s phi coefficient of association. Our analysis on functional traits revealed significant patterns of association with habitat types, including i) saxicolous species with rocky outcrops, ii) epiphytic/epixylic species and vegetative reproduction traits (soredia, isidia) with coniferous stands, and iii) species belonging to the Parmeliaceae family with fens. Rocky outcrops represented the main lichen biodiversity hotspots in the region, while other habitat types were also important for maintaining total and complementary biodiversity. We are confident that our methodological approach including systematic sampling, full habitat variability representation, and the evaluation of complementary biodiversity components, can be effectively applied to fill gaps on lichen biodiversity in other underexplored regions across the globe.