Showy phlox (Phlox speciosa): COSEWIC assessment and status report: chapter 11
Technical Summary
Phlox speciosa
Showy Phlox – phlox de l’Ouest
Range of Occurrence in Canada:
British Columbia
Extent and Area Information
Extent of occurrence (EO) (km²)
Total area encompassed by the 9 populations : 57 km²
Specify trend in EO :
range contraction is uncertain
Are there extreme fluctuations in EO?
probably not, as species is perennial
Area of occupancy (AO) (km²) :
[Sum of areas occupied by the populations] : 0.9-1.4 km²
Specify trend in AO :
unknown but portions of habitat have been lost to developments
Are there extreme fluctuations in AO?
probably not, as species is perennial
Number of known or inferred current locations :
9 populations with 20 sub-populations
Specify trend in # :
unknown, probably stable
Are there extreme fluctuations in number of locations?
probably not, as species is perennial
Specify trend in area, extent or quality of habitat :
unknown, probably relatively stable but some recent losses due to housing developments and quality of habitat has declined due to various anthropogenic activities
Population Information
Generation time (average age of parents in the population) :
unknown, probably 1-5 years
Number of mature individuals :
6,400-57,000
Total population trend:
unknown, probably stable
% decline over the last/next 10 years or 3 generations.
unknown
Are there extreme fluctuations in number of mature individuals?
unknown, probably no
Is the total population severely fragmented?
unknown, considering little is known of the dispersal mechanism (large areas of suitable habitat are present that are not occupied, a fact that might suggest fragmentation)
Specify trend in number of populations :
unknown, probably stable; potential losses are of historic populations
Are there extreme fluctuations in number of populations?
probably not, as species is perennial
List populations with number of mature individuals in each: estimated ranges:
- Ford Lake: 5-9
- McKay Ck.: 20-30
- Park Rill: 60-550
- Twin Lakes: 2100-24,000
- White Lake: 2000-24,000
- Yellow Lake E.: 200-450
- Yellow Lake S.: ?
- Yellow Lake W.: 2000-7500
- Yellowlake Ck.: 6-12
Threats (actual or imminent threats to populations or habitats)
- a large proportion of habitat within the extent of occurrence is on private land and is undergoing rapid development for hobby farms or other land uses that result in habitat loss
- stochastic events based on the small area of occupancy
- weed control activities could threaten populations, especially small ones
- anthropogenic threats, including livestock grazing, range re-seeding, off-road recreation, agricultural cultivation and development, recreational property development, prescribed burning, forest encroachment, road and trail development, and alien plant species introductions
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: Widespread in suitable habitats in the eastern Cascades in Washington and five other states
Is immigration known or possible?
Unknown
Would immigrants be adapted to survive in Canada?
Likely
Is there sufficient habitat for immigrants in Canada?
unknown considering that there exists more “seemingly suitable” habitat than is presently occupied
Is rescue from outside populations likely?
No. Nearest population is > 120 km to the south
Quantitative Analysis
[provide details on calculation, source(s) of data, models, etc] : N/A
Current Status
Status and Reasons for Designation
Status: Threatened
Alpha-numeric code: B1ab (ii, iii, v) + 2ab (ii, iii, v); D2
Reasons for Designation: A showy perennial known from a very small area and from fewer than 10 locations. The species is present within a region subject to on-going habitat loss and degradation as a consequence of private property development, agricultural practices, and the spread of invasive plants.
Applicability of Criteria
Criterion A (Declining Total Population): Not applicable – no data to support specific population decline percentages
Criterion B (Small Distribution, and Decline or Fluctuation): Threatened B1ab (ii, iii, v) + 2ab (ii, iii, v). The species has a very small extent of occurrence (57 km²) and area of occupancy (< 1.5 km²) and is known from fewer than 10 locations with recent losses in area of occupancy, decline in habitat quality and loss of mature individuals as inferred from the considerable decline in natural habitat in the Okanagan and specific examples of likely losses of portions of populations at two sites due to property development. A decline in quality of habitat is also recognized based on practices such as range re-seeding and due to the spread of invasive plants. No recent declines in extent of occurrence have been noted nor have recent populations been lost entirely.
Criterion C (Small Total Population Size and Decline): Not applicable due to large population size. Although the estimate of the population size spans a considerable range due to difficulties in determining population boundaries, the total population size is likely >10,000.
Criterion D (Very Small Population or Restricted Distribution): Threatened D2 (<20 km2 area of occupancy). The number of verified populations is relatively small (<10) and they occur in a region undergoing considerable human population expansion and property development.
Criterion E (Quantitative Analysis): Not available.
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