Lichenometric analysis using genus Rhizocarpon, section Rhizocarpon (Lecanorales: Rhizocarpaceae) at Mount San Lorenzo, southern Chile

Abstract

In this study we present preliminary results on the use of the lichenometric method for age estimation of moraine formation in the Mount San Lorenzo area (47°30' S, 72°21' W), southern Chile. We estimated lichen growth rates of individuals of genus Rhizocarpon, section Rhizocarpon, at two glacier-proximal sites for which independent age estimates were available. These two sites, Lake Shore and Moraine A, presented lichen mean annual growth rates of 0.33 mm and 0.15 mm, respectively. We applied these growth rates to two sites lacking previous dating control: Bedrock and Moraine B, and obtained minimum ages of 70 and 473 years, respectively. Our results allow us to confirm that there is a quantifiable relationship between Rhizocarpon size and age of the substrates in this environment. Based on this result we develop age estimates for sites of unknown age in Mount San Lorenzo. We discuss the factors that possibly determine the variability in the growth of Rhizocarpon in our study sites and compared them with those described in the literature. © Sociedad de Biología de Chile.