Rhizoplaca chrysoleuca as an Alternative Lichenometric Species: a Preliminary Investigation at the Lawn Lake Alluvial Fan, Rocky Mountain National Park, CO USA.

Lichenometry can be a useful tool to date past events when surface ages are unknown. As a method, lichenometry needs to overcome uncertainties in the understanding of lichen biology. Being fairly ubiquitous, Rhizocarpon geographicum is generally used for dating purposes. Other lichens can and have been used for studies, but are often used in conjunction with R. geographicum. This case study suggests that for areas lacking R. geographicum, Rhizoplaca chrysoleuca may be used as an alternate species if the substrate in question does not have substantial R. geographicum growth. While R. geographicum is well-studied, R. chrysoleuca is not, and growth curves have not been established to any extent close to those for R. geographicum. This study uses an alluvial fan in Rocky Mountain National Park created by a dam breach in 1982 as a preliminary baseline to establish a basic R. chrysoleuca growth curve. Age of the substrate is known and was previously unexposed inside a glacial moraine. Assuming lichen growth began soon after the exposure, and as R. chrysoleuca represents the majority species at the site, a basic growth curve can be established, at least in alpine environments. This initial assessment can potentially aid researchers using lichenometry in alpine environments and, more specifically, where sufficient R. geographicum is not present. [ABSTRACT FROM AUTHOR]