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COSEWIC Assessment and Status Report on the Columbian Carpet Moss in Canada

Limiting Factors and Threats

Table 2 (Column B) lists limiting factors and threats for each site. Agricultural practices, including the elimination of wide areas of shrub-steppe to plant vineyards, and the disturbance by domesticated animals appear to be the most serious factors impacting populations of Bryoerythrophyllum columbianum. Other factors, including urban development, road building activities, hiking, and general (natural) erosion, are probably of less significance. Detailed studies are necessary to confirm the degree of threat of any of the above factors.

Vineyards completely eliminate all of the native vegetation when constructed. They are especially common in the south Okanagan valley, one of the centers of distribution in Canada for this moss species. Large areas of the shrub-steppe ecosystem have been lost over the past few decades, and will continue to be lost as more vineyards are developed. Site 1 has probably been lost due to this activity.

The impact from domesticated animals, in particular cattle, is common in arid land areas. Trampling of grazing herds reduces the cover of biological crusts in rangelands with the result, in some areas, of a near complete elimination of viable microbiotic ground cover. Populations of Bryoerythrophyllum columbianum will also be affected. Three of the confirmed populations are probably affected by trampling of cattle. However, these impacts do not completely eliminate the native crusts and they can readily recover once grazing is reduced or eliminated.

Urban development may impact populations. Collection Site 11 may have had its population size reduced by the expansion of a property. Road building and expansion, and erosion that may coincide following these activities may be impacting four populations. Other human impacts, in particular hiking, appear to have impacted, although slightly, eight populations. General (natural) erosion related to steep slopes is a concern at five sites, and may be responsible for the loss of the population at Collection Site 2.