Rayless goldfields (Lasthenia glaberrima) COSEWIC assessment and status report 2000: chapter 11
Technical Summary
Lasthenia glaberrima
Rayless goldfields – Lasthénie glabre
Range of Occurrence in Canada:
British Columbia
Demographic Information
Generation time (average age of parents in the population) :
3 months
Population trend and dynamics
Observed percentage of reduction in total number of mature individuals over the last 10 years.
>>50 %
Projected percentage of reduction in total number of mature individuals over the next 10 years.
Unknown
Observed percentage reduction in total number of mature individuals over any 10-year period, over a time period including both the past and the future.
Unknown
Are the causes of the decline clearly reversible?
Unknown
Are the causes of the decline clearly understood?
Yes
Have the causes of the decline clearly ceased?
No
Observed trend in number of populations :
Stable
Are there extreme fluctuations in number of mature individuals?
Unknown but likely
Are there extreme fluctuations in number of populations?
No
Number of mature individuals in each population
East Sooke Regional Park: approximately 21 left (in 2006), representing a decline from an initial size of about 200 plants
Extent and Area Information
Estimated extent of occurrence (km²) :
1 km²
Observed trend in extent of occurrence :
Unknown
Are there extreme fluctuations in extent of occurrence?
No
Estimated area of occupancy (km²)
Actual area occupied is < 40 m² but based on an overlay of a 1x1 km grid is 1 km². 1 km²
Observed trend in area of occupancy :
Stable
Are there extreme fluctuations in area of occupancy?
No
Is the total population severely fragmented?
Yes
Number of current locations :
1
Trend in number of locations :
Stable
Are there extreme fluctuations in number of locations?
No
Observed trend in quality of habitat :
Decline
Quantitative Analysis
[0.00% probability of extirpation in years]
Threats (actual or imminent, to populations or habitats)
- Trampling (past threat; population enclosed by a fence in 2006)
- Invasive alien plants
- Habitat loss (historical)
- Demographic collapse (potential threat)
- Altered hydrological regimes (potential threat)
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: secure
Is immigration known or possible? Unknown and unlikely :
Unlikely
Would immigrants be adapted to survive in Canada?
Unknown
Is there sufficient habitat for immigrants in Canada?
Yes
Is rescue from outside populations likely?
No
Current Status
COSEWIC: Endangered 2008
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: B1ab(iii,v)+2ab(iii,v); C2a(i,ii); D1
Reasons for Designation: A single very small population of an annual flowering plant that is at continued risk from a number of limiting factors including the spread of exotic plants.
Applicability of Criteria
- Criterion A (Decline in Total Number of Mature Individuals): Not applicable.
- Criterion B (Small Distribution Range and Decline or Fluctuation): Meets Endangered B1ab(iii,v)+2ab(iii,v) with EO and AO well below threshold levels and only a single population known with continued impacts on its habitat and inferred loss of mature individuals.
- Criterion C (Small and Declining Number of Mature Individuals): Endangered C2a(i,ii) with a single population with <2500 plants and continued decline inferred based on the presence and spread of exotic plants.
- Criterion D (Very Small Population or Restricted Distribution): Endangered D1; fewer than 250 plants at the single site.
- Criterion E (Quantitative Analysis): None available
Uncertainties
Other annual species of the genus Lasthenia are known to fluctuate greatly in the number of mature individuals and it is possible that L. glaberrimamay do so.
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