Silver hair moss (Fabronia pusilla) COSEWIC assessment and status report: chapter 11

Summary of Status Report

The only known extant site for the species in Canada, Sumas Mountain, was extensively surveyed recently and Fabronia pusilla was not found. However, this may be the result of the tiny stature of this species combined with the species’ habit of growing under and among other species, making finding F. pusilla difficult. The challenge in finding the species at Sumas Mountain was compounded by the extensive potential habitat for the species there, much of which is inaccessible.

It is possible that Fabronia pusilla is present at more locations in southwestern British Columbia. However, the species’ small stature, in combination with its gregarious habit, may be responsible for it having not been found elsewhere or more frequently in the province. For instance, there are many other dry cliffs and possibly suitable Garry oak habitat in coastal British Columbia that have never been carefully searched specifically for this species (W.B. Schofield, pers. comm. 2002). As a consequence, it is uncertain whether the species is truly rare in Canada, or whether the species’ apparent rarity is an artifact attributable to difficulty associated with finding the species in the field.

John Macoun collected Fabronia pusilla in abundance in the Arrow Lake area in 1890 (Tan 1980). A detailed investigation of this area is recommended as well as a species-specific search in Garry oak and open cliff habitats along the southwestern British Columbia coast. Even though a great deal of bryological research has been completed by W. B. Schofield and his students in this region, most of these surveys are broad-based and designed to collect mosses over wide areas; they are not usually focused on one particular species or its preferred habitat.

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