Mosses and the beginning of plant succession on the Walker Glacier, southeastern Alaska

Abstract

Three mosses, a basidiomycete fungus (perhaps Mycena) and seedlings (perhaps Epilobium) are reported as growing on dead ice of a glacier in southeastern Alaska. By far the most abundant species was Racomitrium fasciculare which appears to begin directly on the ice, and trapping mineral particles, grows up mostly into irregularly shaped patches but it can become more or less hemispheroidal on pedestals of ice. Many of the tufts of which there are thousands, develop to face southeast on tiny mounds of ice and protect the ice to the northwest. However, none appear to become ‘glacier mice’ (more or less spheroidal and lying loose on the ice surface). Sanionia uncinata invades the Racomitrium, as does Pohlia filum. The fungus and three seedlings also occurred only on the moss tufts. In its precise features and topographic situation, this beginning of plant succession on dead ice is of a classical Clementsian type and contrasts strongly with many of the other occurrences of mosses on glaciers in North America, Iceland and Svalbard.