The Problem of Lichen-Free Zones in Arctic Canada

Abstract

The origin of lichen-free areas in the High Arctic has been attributed to lichen-kill under permanent snowfields developed 300 yr ago during the Little Ice Age. There are inconsistencies in this hypothesis, particularly in regard to the manner of lichen-kill, the mechanism of dead lichen removal once the previously ice-covered ground is exposed again, the period when the lichen-kill occurred, and the form of lichen trimlines. An alternative hypothesis is suggested whereby lichen-free areas occur where seasonal snowfields persist for a much greater part of the summer than elsewhere. As a result the lichen growth season there is very short.