Publications

Understanding the spatial distributions of rarity and diversity is crucial for both targeted conservation efforts and elucidating the mechanisms that underpin species richness patterns. Existing studies suggest local communities with greater species richness also hold higher numbers of low abundance species. Rarity hotspots at the global scale tend to be spatially divergent from species richness hotspots and differ among many taxonomic groups, but much less work has been done to understand rarity patterns at the regional scale. Here, we used a large-scale dataset of comprehensive lichen diversity from a global biodiversity hotspot in eastern North America to explore the relationships of rarity, species richness, and elevation, while also examining the key plot characteristics that support increased rarity within the system. We found a mid-elevation slump in lichen rarity, with increased rarity at low and high elevations, contrasting with the mid-elevation hump in species richness for lichens in the same system. Additionally, important plot-level predictors of rarity changed with elevation. Rocky, open habitats hosted increased levels of rarity at low elevations, and the highest, coldest plots at the high elevations also hosted increased levels of rarity. Our results illustrate a contrast between elevational patterns and important plot characteristics for lichen rarity and species richness, suggesting a need for separate, complementary conservation efforts to protect both areas with high species richness and areas with high numbers of rare species.