Niche Relationships Amongst Rhizocarpon Species at Jonas Rockslide, Alberta, Canada

Abstract

Twelve species of Rhizocarpon coexist with 94 other species of saxicolous lichens at Jonas Rockslide, Jasper National Park, Alberta, Canada. The position of each Rhizocarpon species in the community is assessed with respect to environmental factors and biotic relationships. Each species shows distinct correlations with measured environmental factors and a different set of interactions with other species. Rhizocarpon bolanderi and R. superficiale stand out as opposites with regard to their biotic associations and environmental correlations. Competition between pairs of Rhizocarpon species is predicted to vary in intensity, as some species pairs never occupy the same microenvironment, whereas others frequently occur in similar locations. Using thallus diameter as a measure, there is evidence of high recruitment rates into populations of the sub-genus Phaeothallus and lower recruitment rates in the sub-genus Rhizocarpon.