Lichenometric dating of Little Ice Age glacier moraines using explicit demographic models of lichen colonization, growth, and survival

Auteur(s) et Affiliation(s)



Description :
To date 3 terminal moraines of an Alaskan glacier, the AA. used a new lichenometric technique in which surfaces are dated by comparing lichen population distributions with the predictions of ecological demography models with explicit rules for the biological processes that govern lichen populations : colonization, growth, and survival. Working with 2 lichen taxa, the AA. used multinomial-based likelihood functions to compare model predictions with measured lichen populations, using only the thalli in the largest 25% of the size distribution. Joint likelihoods that combine the results of both species estimated moraine ages of AD 1938, 1917, and 1816. Ages predicted by Rhizocarpon alone were older than those of P. pubescens. Predicted ages are geologically plausible, and reveal glacier terminus retreat after a Little Ice Age maximum advance around AD 1816, with accelerated retreat starting in the early to mid twentieth century. Importantly, this technique permits calculation of prediction and model uncertainty.


Type de document :
Article de périodique

Source :
Geografiska annaler. Series A. Physical geography, issn : 0435-3676, 2014, vol. 96, n°. 1, p. 21-41, nombre de pages : 21, Références bibliographiques : 2 p.

Date :
2014

Editeur :
Pays édition : Suede, Stockholm, Svenska sällskapet för antropologi och geografi