Cryptic paw (Nephroma occultum) COSEWIC assessment and status report: chapter 11

Technical Summary

Nephroma occultum

Cryptic paw – lichen cryptique

Range of Occurrence in Canada:

British Columbia

Extent and Area Information

Extent of occurrence (EO)(km²) the Canadian EO as approximated from a map of the known distribution :

Approximately 498,000 km²

Specify trend in EO :

Unknown

Are there extreme fluctuations in EO?

No

Area of occupancy (AO) (km²)

assuming that the average population occupies approximately 25 (5 m x 5 m) and there are 45 populations known in Canada, the total area of occupancy is approximately 1,125 m². 1,125m²

Specify trend in AO :

Unknown

Are there extreme fluctuations in AO?

Unknown

Number of known or inferred current locations (in Canada) :

45

Specify trend in # :

Unknown, but possibly decreasing; 2 original sites lost

Are there extreme fluctuations in number of locations?

No

Specify trend in area, extent or quality of habitat :

Extent of potential habitat declining

Population Information

Generation time (average age of parents in the population) :

Unknown

Number of mature individuals (in Canada):

Approximately 450

Total population trend:

% decline over the last/next 10 years or 3 generations.

Unknown – most original sites not re-surveyed

Are there extreme fluctuations in number of mature individuals?

Unknown

Is the total population severely fragmented?

No

Specify trend in number of populations:

Unknown, but possibly declining because of continued forest harvesting

Are there extreme fluctuations in number of populations?

No

List populations with number of mature individuals in each:

approximately 45 populations in Canada with a range of 1-40 individuals per population.

Threats (actual or imminent threats to populations or habitats)

  • Continued forest harvesting, particularly in inland cedar-hemlock forests.
  • Hemlock looper infestations.
  • Forestfire.
  • Lengthened summer drought related to climate change.

Rescue Effect (immigration from an outside source)

Unlikely

Status of outside population(s)?

USA: 6 populations in Alaska; 8 in Washington; 182 in Oregon.

Is immigration known or possible?

Unlikely

Would immigrants be adapted to survive in Canada?

Yes

Is there sufficient habitat for immigrants in Canada?

Yes, though in decline

Is rescue from outside populations likely?

No

Quantitative Analysis

Not applicable

Current Status

COSEWIC: Assessed as Special Concern in 1995. Status was re-confirmed in 2006.

Status and Reasons for Designation

Status:  Special Concern

Alpha-numeric code:  Not applicable

Reasons for Designation : This foliose lichen is endemic to western North America where it is known in Canada from 45 locations, however, there are likely more undiscovered locations. The Canadian sites account for more than 50% of the global range with only 5 locations protected from forest harvesting. The species has restricted habitat requirements and grows in mid to lower canopy of old growth coastal and interior humid cedar-hemlock forest. It reproduces only by vegetative propagules with limited dispersal distance. The species is vulnerable to forest harvesting, changes in understory humidity, insect defoliation (hemlock looper), and fire.

Applicability of Criteria

  • Criterion A: (Declining Total Population): Does not meet criterion. Data insufficient to document population decline.
  • Criterion B: (Small Distribution, and Decline or Fluctuation):  Not known. Although the species meets AO criteria for Endangered and Threatened, and a continuing decline can be shown for area, extent and/or quality of habitat, there is uncertainty on decline in population size, fluctuation, and fragmentation.
  • Criterion C: (Small Total Population Size and Decline): Does not meet criterion. Total population size and decline are unknown.
  • Criterion D: (Very Small Population or Restricted Distribution): The population size at all sites is unknown. Does not satisfy Threatened, D2, because it cannot be shown that the species is prone to extirpation by anthropogenic effects in a short period of time.
  • Criterion E: (Quantitative Analysis): Not applicable.

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