Houghton's goldenrod (Solidago houghtonii) COSEWIC assessment and status report: chapter 11
Technical Summary
Solidago houghtonii
Houghton’s goldenrod – Verge d’or de Houghton
Range of Occurrence in Canada:
Ontario
Extent and Area Information
Extent of occurrence (EO) (km²)
220 km² [sum of the alvar areas occupied by the populations]
Specify trend in EO
unknown but likely stable
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km²)
0.075 km² (7.5 ha) [sum of the occupied areas]
Specify trend in AO
unknown but possibly stable (lack of specific monitoring for this species)
Are there extreme fluctuations in AO?
unlikely
Number of known or inferred current locations
13
Specify trend in #
stable
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat
unknown for these sites but alvars in Ontario are a very rare habitat that have been impacted by development and exotics plants
Population Information
Generation time (average age of parents in the population)
several years
Number of mature individuals
est. 27,000 flowering, but due to asexual reproduction there are likely fewer distinct genets present than the estimated total number of mature plants
Total population trend:
likely stable
% decline over the last/next 10 years or 3 generations.
N/A
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
no but somewhat fragmented
Specify trend in number of populations
likely stable
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
- La Cloche area ~ 9080
- Cockburn Island “hundreds”
- Tamarack Bay ~ 4500
- Cabot Head ~ 12,520
Threats (actual or imminent threats to populations or habitats)
- recreational activities (particularly ATV’s)
- quarrying activities may become a threat but presently do not seem to impact the populations
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: Michigan S3; New York S1(20% of historical populations lost in USA)
Is immigration known or possible?
unknown
Would immigrants be adapted to survive in Canada?
unknown
Is there sufficient habitat for immigrants in Canada?
yes
Is rescue from outside populations likely?
seeds might be able to reach Cockburn Island (the westernmost area of occurrence in Ontario) from sites in northern Michigan
Quantitative Analysis
N/A [provide details on calculation, source(s) of data, models, etc]
Current Status
COSEWIC:Special Concern (May 2005)
Status and Reasons for Designation
Status: Special Concern
Alpha-numeric code: Met criterion for Threatened, D2, but designated Special Concern because many of the plants are in inaccessible areas and in a provincial nature reserve.
Reasons for Designation: A Great Lakes endemic present in Ontario primarily within alvar habitats at the tip of Bruce Peninsula and on Manitoulin Island. The few populations occupy very small areas of provincially rare alvar habitat that are at potential risk from aggregate extraction, use of recreational vehicles and expansion of invasive weeds.
Applicability of Criteria
- Criterion A (Declining Total Population): Insufficient information for declines
- Criterion B (Small Distribution, and Decline or Fluctuation): Not met although extent of occurrence and area of occupancy are well below critical criterion limits for endangered and threatened and a decline in quality of habitat may occur in future; however, the species is presumably not highly fragmented in spite of the discontinuous alvar habitats because wind dispersal of fruitlets may enable recolonization. Also, the populations of this perennial species are not likely to undergo extreme fluctuations.
- Criterion C (Small Total Population Size and Decline): Population size is estimated to exceed considerably the maximum limit of 10,000 mature individuals.
- Criterion D (Very Small Population or Restricted Distribution): Meets threatened D2 based on a very small area of occupancy <1 km² and presence of ongoing threats from habitat loss from quarry activities in adjacent alvar sites, the likelihood of increased recreational use by ATVs and continued competition from exotic invasives on alvar sites. However, the species may be best regarded as of special concern at present since the risks are limited and about 2/3 of the total population is protected due to the presence of nearly one half of the total population in Cabot Head Provincial Nature Reserve and a sizable number are present at relatively inaccessible locations.
- Criterion E (Quantitative Analysis): Insufficient information.
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