Publications

Abstract: The lichen biota of eastern North America is fairly well-documented with most taxa reported from terrestrial ecosystems. While some taxa are described as living near water bodies potentially subjected to inundation, no amphibious lichen communities have been described. To address this gap in our understanding of the region’s lichen ecology, thirteen rocky river sites in two river basins of central North Carolina, U.S.A. were explored for amphibious and riparian lichen biotas during periods of low water level, restricted to saxicolous species subjected to inundation, however infrequent. Specimens of encountered taxa were collected and their heights above water level were measured during field visits. Three communities were discerned from field observations in increasing height from low water level, here termed: Mesic Fluvial, Xeric Fluvial and Riparian. These communities are described in terms of species number and composition, height above water, functional traits and taxonomic class composition, as well as characteristic species both in open riverscour and shaded rocky riverbank habitats. From measured heights, two trimlines are described separating the three communities: Fluvial Trimline, often co-occurring with a band of deposited silt, and Riparian Trimline. With the use of nearby stream gage height data, percent inundation for the 2023 water year was estimated for the three communities as 3–10 months for Mesic Fluvial, 0.5–4 months per year for Xeric Fluvial, and < 1–3 months for Riparian lichens. Environmental variables were explored for relationships with the three communities, finding the most significant positive relationships between Mesic Fluvial species richness and several stream physical and water chemistry variables. Recommendations for future stream lichen surveys are offered.