Slender collomia (Collomia tenella) COSEWIC assessment and status report: chapter 5

Habitat

Habitat requirements

Collomia tenella occurs in the southern interior of British Columbia along the Similkameen river valley in the Interior Douglas-fir biogeoclimatic zone (Hope et al. 1991). Climatic conditions in this region are continental, characterized by hot, dry summers, a fairly long growing season and cool winters. A rainshadow effect prevails in this area due to the presence of the Coast-Cascade Mountains to the west.

Within this region, Collomia tenella occurs on eroded, steeply-sloped, southeast-facing sections of a sandy ridge. The sandy ridge, formed by fluvial processes during the last glaciation, consists of fine-textured sands. The eroded sections of the slopes are sparsely vegetated with about 20% cover. The vegetation consists of a variety of herbs and shrubs including Balsamorhiza sagittata (arrow-leaved balsamroot), Astragalus miser (timber milk-vetch), Collomia linearis (narrow-leaved collomia), Phacelia linearis (thread-leaved phacelia), Lupinus sericeus (silky lupine), Amelanchier alnifolia (Saskatoon), Linaria genistifolia ssp. dalmatica (Dalmation toadflax), Bromus tectorum (cheatgrass), and Pseudoroegneria spicata (bluebunch wheatgrass). Scattered Douglas-fir (Pseudotsuga menziesii) and Ponderosa Pine (Pinus ponderosa) also occur on the ridge.

Trends

Noxious weeds, such as Linaria genistifolia and Bromus tectorum could increase at the site as they have in many other areas in the southern interior of British Columbia and potentially decrease the available habitat.

Protection/ownership

The population of Collomia tenella in British Columbia occurs on private property in the Agricultural Land Reserve.

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