Silver hair moss (Fabronia pusilla) COSEWIC assessment and status report: chapter 5

Habitat

Habitat requirements

In North America, Fabronia pusilla is usually found in seasonally dry habitats in areas with hot summers, preferring either rock or tree bark as substrates. At the Sumas Mountain site, it was found in a cranny on a dry vertical sandstone cliff, and on a damp shaded sandstone cliff face. It was reported from crevices of steep rocks of undetermined type at the Arrow Lake site. A common habitat in California is on the undersides of leaning trunks or limbs (A. Whittemore, pers. comm. 2001), especially those of oaks (Schofield, pers. comm. 2001). Here it can also be found on rock, especially on underhangs of rock walls and in crevices (J. Shevock, pers. comm. 2001), and it has also been collected on soil over rock in Colorado. More precise habitat information is lacking for this species.

Trends

The sandstone cliffs near Abbotsford are very extensive (about 1.5 km. in length, although somewhat patchy, broken up by talus and forest; Fig. 3 shows the site from about 2 km to the south). Many of the steep and high cliff faces are inaccessible, and unavailable for survey (Figs. 4 and figure5 illustrate typical habitat features of the site).

Figure 3. Sumas Mountain site with approximate extent of sandstone cliffs noted by yellow dots (length approximately 1.5 km.).

Figure 3. SumasMountainsite with approximate extent of sandstone cliffs noted by yellow dots (length approximately 1.5 km.)

Figure 4. Typical semi-open habitat near sandstone cliffs at Sumas Mountain site.

Figure 4.Typical semi-open habitat near sandstone cliffs at SumasMountainsite

Figure 5. Typical open habitat near sandstone cliffs at Sumas Mountain site.

Figure 5. Typical open habitat near sandstone cliffs at SumasMountainsite

General habitat trends in the Abbotsford site appear stable. We visited the site on three days, in November and December, 2001, and found little disturbance to the rock faces, even though hiking is common along some areas at the base of the cliffs. A number of areas along Sumas Mountain are presently being proposed for development, but the sandstone cliffs on which this moss was found are not within development boundaries. Potential additional sites of suitable habitat may exist for this species across southern British Columbia, such as along the eastern portions of the Fraser River valley, in the Arrow Lake area, and, possibly, on Garry oaks and associated rock habitats along the coast.

Protection/ownership

The site is under private ownership.

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