Influence of Sampling Design on Lichen Size-Frequency Distributions and its Effect on Derived Lichenometric Indices

Abstract

The 1-in-1000 thallus and the gradient of the log-linear regressions of lichen size-frequency distributions have been suggested as potential age indices. Both are dependent on the assumption that the frequency distribution fits the log-linear model. Distributions drawn from a single moraine show major variations depending on the location at which they are obtained. The variations primarily reflect the effect of late-lying snowbanks and secondarily the effect of altitude. The goodness-of-fit with the log-linear model is significantly affected by the class of measurement interval used, with 5-mm intervals yielding a much better fit than 1-mm intervals. The 1-in-1000 thallus diameter is less variable than the gradient of the log-linear regression, but the relative advantages of the two may be masked by differences in their time sensitivity.