Seaside bone (Hypogymnia heterophylla) COSEWIC assessment and status report: chapter 11

Hypogymnia heterophylla
Seaside bone Hypogymnie maritime
Range of Occurrence in Canada: British Columbia

 

Extent and Area information
• Extent of occurrence (EO)(km2²) Polygon of EO was drawn around Canadian point locations in GIS application. 8.70 km2
· • Specify trend in EO stable
·• Are there extreme fluctuations in EO? no
·• Area of occupancy (AO) (m2) Area of occupancy is calculated at 25 m2.per subpopulation; 10 Canadian subpopulations of Hypogymnia heterophylla = 250 m2 8 km2 using a 2km x 2km grid. Actual occupation is 250 m22
·• Specify trend in AO stable
·• Are there extreme fluctuations in AO? no
·• Number of known or inferred current locations 4 in Canada
·• Specify trend in # stable
·• Are there extreme fluctuations in number of locations? no
·• Specify trend in area, extent or quality of habitat stable

 

Population Information
·        Generation time (average age of parents in the population) 10-15 years
·        Number of mature individuals unknown but likely > 1000 thalli
·        Total population trend: stable 
·     % decline over the last/next 10 years or 3 generations.  unknown
·        Are there extreme fluctuations in number of mature individuals?  no
·        Is the total population severely fragmented? no
·     Specify trend in number of populations  stable
·     Are there extreme fluctuations in number of populations? no

 

List subpopulations with number of mature individuals in each:
1. Park Pike’s Point and Iron Mine Bay areas: 
East Sooke 1  >100
East Sooke 2  >100
East Sooke 3  >100
2. Aldridge Point area to Beechy Head
East Sooke 4  >100
East Sooke 5  >100
3. Bentick Island 
Bentinck Is 6  >10
Bentinck Is. 7 >10
Bentinck Is. 8 >100
Bentinck Is. 9 >100
4. Sheringham Point
Sheringham Point 10  >100

 

Threats (actual or imminent threats to populations or habitats)
Severe winter storms of 2006/2007 damaged many individual coastal trees in East Sooke Regional Park; debris will be left in place on the ground.

 

Rescue Effect (immigration from an outside source)
·        Status of outside population(s)? USA: 3 populations in Washington, south of Canadian populations; many populations in Oregon and California
·Is immigration known or possible? possible, from Puget Sound
·Would immigrants be adapted to survive in Canada? yes
·Is there sufficient habitat for immigrants in Canada? unknown
Is rescue from outside populations likely? unknown
Quantitative Analysis [provide details on calculation, source(s) of data, models, etc] Not applicable

Current Status

 

COSEWIC: Special Concern (1996), Threatened (2008)

 

Status and Reason for Designation

Status: Threatened Final Criteria: D2

Status History:

Designated Special Concern in April 1996. Status re–examined and designated Threatened in April 2008.

Reason for Designation:

This lichen is endemic to the Pacific Coast of North America, and southwest Vancouver Island represents the northern limit of its range. The species’ survival depends on early to intermediate seral shore pine forests along the sea coast The populations appear to be stable, but have a restricted occurrence and the species is known from only four locations. Severe winter storms, which are anticipated to increase, are the main threat to the species.

Availability of Criteria
Criterion A: Not applicable. Does not meet criterion: no evidence of decline.
Criterion B: Not applicable. Does not meet criterion: no evidence of decline or fluctuation.
Criterion C: Not applicable. Does not meet criterion: no evidence of decline.
Criterion D: Does not meet criteria for Threatened D1 (# of individuals likely > 1000), but meets criteria for Threatened D2, with number of locations < 5, and the habitat is prone to the effects of stochastic events (winter storms) within a very short time period in an uncertain future.
Criterion E: Not applicable.

 

 

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