The Problem of Lichen-Free Zones in Arctic Canada

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