Dense spike-primrose (Epilobium densiflorum) COSEWIC assessment and status report: chapter 11
Technical Summary
Epilobium densiflorum
Dense Spike-primrose – épilobe densiflore
Range of Occurrence in Canada:
British Columbia
Extent and Area Information
Extent of occurrence (EO) (km²)
Sum of the coastal area within which extant populations occur. 900 km²
Specify trend in EO :
declining (loss of North Pender Is. population since 1981)
Are there extreme fluctuations in EO?
no
Area of occupancy (AO) (km²)
Sum of the individual separate localities. 0.1 km² (10.1 ha)
Specify trend in AO :
declining
Are there extreme fluctuations in AO?
no
Number of known or inferred current locations :
4
Specify trend in # :
declining
Are there extreme fluctuations in number of locations?
no
Specify trend in area, extent or quality of habitat :
declining
Population Information
Generation time (average age of parents in the population)
<1 year
Number of mature individuals :
2,850-3,350
Total population trend:
declining
% decline over the last/next 10 years or 3 generations.
10%
Are there extreme fluctuations in number of mature individuals?
no
Is the total population severely fragmented?
severely fragmented with no reasonable likelihood of genetic exchange
Specify trend in number of populations:
declining
Are there extreme fluctuations in number of populations?
no
List populations with number of mature individuals in each:
- Population No. 1: 2,000-2,500
- Population No. 2: 1
- Population No. 3: 50
- Population No. 4: 800
Threats (actual or imminent threats to populations or habitats)
- existing threats: habitat destruction (residential development); habitat alteration (altered hydrological regime, invasion by alien plants)
- potential threats: housing developments covering site 1
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: G5 – globally secure, but rare in San Juan County (USA) and absent from other counties adjacent to southwest British Columbia
Is immigration known or possible?
no
Would immigrants be adapted to survive in Canada?
unknown
Is there sufficient habitat for immigrants in Canada?
not likely
Is rescue from outside populations likely?
no
Quantitative Analysis
[provide details on calculation, source(s) of data, models, etc.] : N/A
Current Status
COSEWIC:Endangered 2005
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: A3c; B1ab (i, ii, iii, iv,v) + 2ab (i, ii, iii, iv, v)
Reasons for Designation: An annual herb of a restricted habitat type within the Garry Oak Ecosystem that has undergone significant declines in number of populations and is subject to continued habitat reduction due to development and the spread of exotic weeds. The four extant populations are fragmented, small, and have little chance of being repopulated from adjacent sites in Washington State should they become extirpated.
Applicability of Criteria
- Criterion A (Declining Total Population): Meets endangered A3c with a 75% loss anticipated if all or most of population 1 is lost due to housing or other commercial development.
- Criterion B (Small Distribution, and Decline or Fluctuation): Meets Endangered B1ab (i,ii,iii,iv,v) + 2ab (i,ii,iii,iv,v) based on its small extent of occurrence and area of occupancy, only 4 remaining populations and continuing decline in extent of occurrence, area of occupancy (loss of most of population 2), quality of habitat (exotic weeds), number of populations and number of mature plants.
- Criterion C (Small Total Population Size and Decline): Meets threatened C1, based on a population of <10,000 and a potential future decline projected of about 75% if most of population 1 is lost to site development.
- Criterion D (Very Small Population or Restricted Distribution): Meets threatened D2 based on a very small area of occupancy and occurrence at only 4 locations with ongoing threats from urban expansion and exotic weeds.
- Criterion E (Quantitative Analysis): N/A