Rosy owl-clover (Orthocarpus bracteosus) COSEWIC assessment and status report: chapter 11
Technical Summary
Orthocarpus bracteosus
Rosy owl-clover – orthocarpe à épi feuillu
Range of Occurrence in Canada: British Columbia
Extent and Area Information
Extent of occurrence (EO) (km²) :
(Actual area of single population)
<<1 km²
(0.03 ha)
Specify trend in EO :
Historic decline
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km²) :
(Actual area of single population)
<<1 km²
(0.03 ha)
Specify trend in AO :
Historic decline
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations :
1
Specify trend in # :
Historic decline
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat :
Historic decline in extent of habitat but recent continued decline of quality due to encroachment by invasive plants and impact of trampling.
Population Information
Generation time (average age of parents in the population) :
1 year
Number of mature individuals :
300 in 2002 but as low as 40 recorded in 1998
Total population trend:
Unkown (Numbers fluctuate)
% decline over the last/next 10 years or 3 generations.
Decline uncertain due to fluctuation in numbers
Are there extreme fluctuations in number of mature individuals?
Large, if not extreme, fluctuations have been documented.
Is the total population severely fragmented?
Yes (Single population disjunct from Washington State population by 300 km)
Specify trend in number of populations:
Stable (Historic decline)
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
Trial Island: 300 in 2002
Threats (actual or imminent threats to populations or habitats)
Actual:
- alien species invasion,
- foot-traffic
Potential:
- marine pollution
- any stochastic event that would severely impact the small area occupied by the single population of this species
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: Extremely rare in Washington (S1)
Is immigration known or possible?
Unlikely
Would immigrants be adapted to survive in Canada?
Unknown
Is there sufficient habitat for immigrants in Canada?
Small amounts of unoccupied, suitable habitat remain
Is rescue from outside populations likely?
No
Quantitative Analysis
Not Applicable
Other Status
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: B1ab(iii)+2ab(iii); C2a(i, ii); D1
Reasons for Designation: An annual herb of vernal pools and damp depressions present at a single remaining location where population size fluctuates widely with low numbers that may be fewer than 100 plants a year. Expansion is limited due to lack of suitable habitats and apparent low dispersal abilities. The population is at risk from spread of nearby invasive exotic plants, from trampling due to hiker traffic and local maintenance activities related to the nearby communications site and consequences of possible oil spills occurring in the busy shipping lanes surrounding the island site.
Applicability of Criteria
Criterion A (Declining Total Population): Not Applicable: Populations fluctuate greatly with no consistent trend evident.
Criterion B (Small Distribution, and Decline or Fluctuation): Endangered under B1 and B2 (a) + (b iii) due to small distribution with EO and AO of <<1ha at the single remaining site with continuing decline in quality of habitat due to encroachment by invasive plants.
Criterion C (Small Total Population Size and Decline): Endangered under C2 a(i, ii) based on an inferred decline of mature plants in the future due to the spread of invasive plants and all plants in one population.
Criterion D (Very Small Population or Restricted Distribution):Endangered under D1 due to presence in some years of <250 plants.
Criterion E (Quantitative Analysis): Not Applicable.
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