On the Dispersal of Hair Lichens (Bryoria) in High-Elevation Oldgrowth Conifer Forests

Abstract

Arboreal hair lichens belonging to the genus Bryoria provide crucial winter food for the threatened Mountain ecotype of the Woodland Caribou. Earlier studies suggest that the reliance of many Bryoria species on thallus fragmentation as a primary mode of reproduction can lead to low dispersal rates. This paper examines the occurrence of thallus fragments over a snow-covered subalpine meadow following a late winter windstorm of moderate force. Fragment densities were greatest immediately downwind of the forest edge, but remained substantial even at a distance of 2 km. This suggests that dispersal is not limiting for at least some Bryoria species at subalpine elevations. It is proposed that the ecological requirement of Bryoria fremontii and B. pseudofuscescens for well-ventilated habitats considerably enhances their ability to inoculate young, regenerating stands over considerable distances. Their observed general absence in young trees is probably a function of substrate limitations rather than of limitations of dispersal.