INVESTIGADORES
GARIBOTTI irene Adriana
congresos y reuniones científicas
Título:
Lichenometry in the Patagonian Andes: A study of Rhizocarpon geographicum growth rates in relation to climatic variations
Autor/es:
GARIBOTTI, I.A.; MASIOKAS, M.H.; VILLALBA, R.
Lugar:
Malargue, Mendoza
Reunión:
Simposio; Simposio Internacional PAGES; 2006
Institución organizadora:
PAGES
Resumen:
Although lichenometry has a large potential for dating glacier fluctuations during recent centuries, it has rarely been used in the Patagonian Andes. We evaluate the usefulness of Rhizocarpon geographicum for dating glacier deposits based on the development of lichenometric growth curves. Five glacier forelands, two in the north (41° S) and three in the south (49° S) sectors, were investigated along the Patagonian Andes. Lichen diameters were measured in surfaces previously dated using historical photographs and tree-ring methods. R. geographicum growth rates range between 0.09 and 0.56 mm yr-1. Growth rates are significantly higher in wetter than in drier sites. Rates of growth generally reflect the steep west-east gradient in precipitation across the Andes. Logarithmic and linear growth curve models were identified. The logarithmic model better fits the growth rates in wetter sites, whereas the linear model does in drier sites. We conclude that R. geographicum growth is affected in larger degree by moisture conditions (as related to the precipitation gradient) than by latitudinal differences. To increase our confidence in the use of lichenometry across the Patagonian Andes, more glacier forelands will be surveyed and additional control points with well-documented ages identified.