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COSEWIC assessment and status report on the Alkaline Wing-nerved Moss in Canada

Limiting Factors and Threats

Table 3 lists limiting factors and threats for each site. The major limiting factor and threat to Pterygoneurum kozlovii appears to be the trampling of its habitat by domestic animals, usually cattle, but also, in a few cases, horses. Most alkaline areas in the province are not protected, and are used by cattle for drinking water, and heavy disturbance in these areas is frequent. Population 8 near Riske Creek may have been lost because of extensive trampling by cattle. Urban development has probably eliminated some alkaline ponds and their associated populations of this species (northwest of Osoyoos and west of Kamloops). Highway expansion has eliminated Population 4 west of Osoyoos. Population 16 near Cranbrook is threatened by the heavy recreational use of this site by vehicles, especially ATVs. Much of the area is denuded of vegetation, and only small patches of potential habitat for this species remains.

A further threat may be long periods of drought. The last four to five years have been particularly dry in some areas of interior British Columbia, and many populations may have declined because of this drought. They have been covered by more than usual plant litter or by soil from gopher or ground squirrel throws. It is possible that these animals are taking advantage of the drier conditions of these sites; burrows are common at the driest sloughs, and absent where some soil moisture exists.