Brook spike-primrose (Epilobium torreyi) COSEWIC assessment and status report: chapter 5

Habitat

Habitat requirements

In Canada, Epilobium torreyi occurred on moist grasslands and open slopes associated with Garry oak ecosystems in the lowland Coastal Douglas-fir biogeoclimatic zone (Douglas and Meidinger 1999, Fuchs 2001). The populations occurred on clay-rich, marine sediments that were wet during the winter months and very dry in the summer. The great fluctuations in moisture conditions discouraged growth by woody plants and many herbs; consequently the vegetation was open at both sites. There are no records of vegetation composition at the McTavish Road site but the Craigflower meadow site, during years immediately before its extirpation, was dominated by a mix of native and exotic herbs along with a sparse cover of invasive shrubs such as Cytisus scoparius and Crataegus monogyna.

In Oregon, Epilobium torreyi occurs on moist, low ground (Peck 1961; Gilkey and Dennis 1967). In California, it occurs along stream banks and on moist slopes below 2600 metres (Hoch 1993). Epilobium torreyi has been observed on seasonally moist sites that dry out during the summer, sometimes before flowering has ended (Davis 1952, Raven and Moore 1965).

Habitat trends

Less than 1% of the Coastal Douglas-fir biogeoclimatic zone remains in a relatively undisturbed state (Pacific Marine Heritage Legacy 1996). Garry oak ecosystems in the Victoria region have declined from 10,510 ha in 1,800 to 512 ha in 1997 (Lea 2002); even more has been lost since then, and most of what remains has been heavily altered through invasion by alien grasses and shrubs. Habitats suitable for Epilobium torreyi have probably suffered proportional declines in area and quality due to their association with Garry oak ecosystems (Fuchs 2001).

Habitat protection/ownership

British Columbia does not have any general legislation specifically protecting the habitat of species at risk.

The Craigflower Meadow population (extirpated) occurred within Thetis Lake Regional Park. The Capital Regional District (CRD) has recently given the conservation and management of rare threatened and endangered plants and wildlife, and their supporting habitats, precedence over all other park uses (Capital Regional District Parks 2000). The McTavish Road population (extirpated) occurred on private land and even if it could be reintroduced, the habitat would have no legal protection.

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