Macoun’s meadowfoam (Limnanthes macounii) COSEWIC assessment and status report: chapter 11
Technical Summary
Limnanthes macounii
Macoun’s meadowfoam – Limnanthe de Macoun
Range of Occurrence in Canada:
British Columbia
Extent and Area Information
Extent of occurrence (EO) (km²)
40 km², 200 km coastline x 0.2 km
Specify trend in EO
stable (recent finds likely representing previously unknown localities)
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km²)
< 0.02 km² total of individual patch (sub-population) areas
Specify trend in AO
fluctuates but likely overall decline based on impact of expanding populations of exotic plants
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations
28
Specify trend in #
[note that for plants location or site = population] likely best considered as a decline in number of localities-sub-populations. Slight increase in overall number (24 to 28) due to increased search effort but likely best considered as a decline when considering that out of 52 original sub-populations 29% (15) disappeared, including 4 whole populations (although these were not major sites)
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat
decline in habitat quality
Population Information
Generation time (average age of parents in the population)
several months (winter annual)
Number of mature individuals
about 20,000
Total population trend:
likely a decline:
- 29% lost
- 27% declined
- 19% stable
- 23% increased
(based on the 52 sub-populations documented in original report in 1988)
% decline over the last/next 10 years or 3 generations.
decline of 8 to 12 % in absolute numbers in the past 10 years (net loss of about 800 to 1,200 individuals)
Are there extreme fluctuations in number of mature individuals?
uncertain if extreme fluctuations but considerable yearly variation occurs
Is the total population severely fragmented?
extreme fragmentation (smaller populations occupy areas les than 1 m² and there would be seemingly no genetic exchange among them since the plants are self-pollinated and lack dispersal mechanism)
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
see Appendix
Threats (actual or imminent threats to populations or habitats)
Loss of habitat due to: property developments on a number of sites and competition with introduced exotic plants, especially annual grasses
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: none
Is immigration known or possible?
no (endemic)
Would immigrants be adapted to survive in Canada?
N/A
Is there sufficient habitat for immigrants in Canada?
N/A
Is rescue from outside populations likely?
N/A
Quantitative Analysis
N/A
Previous Status
Previous COSEWIC assessment : Special Concern
Status and Reasons for Designation
Status: Threatened
Alpha-numeric code: Met criteria for Endangered, B1ab(iii)+2ab(iii), but designated Threatened, B1ab(iii)+2ab(iii); D2, because the species does not seem to be at imminent risk of extirpation.
Reasons for Designation: A Canadian endemic highly restricted within a narrow coastal fringe of seasonally wet microhabitats where it is at risk from continued competition with a wide range of exotic plants. Its presence in a highly urbanized area results in habitat disruption and population losses.
Applicability of Criteria
- Criterion A (Declining Total Population):Not met (rough estimate of decline in last 10 years is perhaps only 8-12%)
- Criterion B (Small Distribution, and Decline or Fluctuation): Meets Endangered B1ab (iii) + 2ab (iii), based on the small extent of occurrence and occupancy, the highly fragmented nature of the populations and the considerable impact on habitat quality due to human activities and invasive plants; populations are considered highly fragmented since they occur as small patches within seasonally wet depressions and appear to be primarily self-pollinated with no specialized means of dispersal likely resulting in limited genetic exchange. Fragmentation may also have been promoted by habitat disruption in this highly populated region. Meets Endangered but recommended as Threatened since the species does not seem to be at imminent risk of extirpation with perhaps only an 8-12% estimated loss in about 15 years.
- Criterion C (Small Total Population Size and Decline): Not met (Population size is too large).
- Criterion D (Very Small Population or Restricted Distribution): Threatened D2 based on a very small area of occupancy <20km² and at on-going risks due to presence in a highly urbanized region and from the spread of invasive plants.
- Criterion E (Quantitative Analysis): Not applicable
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