Patterns in the occupancy and abundance of the globally rare lichen Erioderma pedicellatum in Denali National Park and Preserve, Alaska

To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.\ud This is the publisher’s final pdf. The published article is copyrighted by The American Bryological and Lichenological Society, Inc. and can be found at: http://www.abls.org/.We investigated habitat attributes related to the occupancy of the globally rare and endangered\ud epiphytic lichen, Erioderma pedicellatum, in a newly discovered (2009) population center in Denali National\ud Park and Preserve (DNPP), Alaska. We measured forest, tree and epiphytic lichen community\ud characteristics on eighty-five systematically selected plots in four study areas. We aggregated these data\ud at three spatial scales (tree, plot and study area) at which to compare E. pedicellatum occupancy (probability\ud of occurrence) and abundance to environmental covariates. We observed 2,035 E. pedicellatum thalli on 278\ud individual Picea glauca stems. The species occurred in 61% of the plots measured. Occupancy of E.\ud pedicellatum at the individual tree-scale was influenced by stem diameter, study area, live crown length, plot\ud P. glauca basal area, plot canopy cover and distance to open water. Our models for E. pedicellatum\ud occupancy at the plot-scale identified study area, P. glauca density, deciduous basal area (Betula neoalaskana\ud and Populus trichocarpa), and tall shrub cover ($ 200 cm in height) as significant covariates. Our estimates\ud of the DNPP population size increase the world population by at least tenfold to approximately 100,000\ud thalli. We suggest important topics for further research on E. pedicellatum