Nugget moss (Microbryum vlassovii) COSEWIC assessment and status report: chapter 11
Technical Summary
Microbryum vlassovii
Common name: Nugget Moss – Phasque de Vlassov
Occurrence by province:
British Columbia
Extent and Area information
extent of occurrence (EO) (km²) :
400 km²
specify trend (decline, stable, increasing, unknown) :
unknown
are there extreme fluctuations in EO (> 1 order of magnitude)?
unknown
area of occupancy (AO) (km²)
<1 km²
specify trend (decline, stable, increasing, unknown) :
unknown
are there extreme fluctuations in AO (> 1 order magnitude)?
unknown
number of extant locations :
2, one population re-located in recent survey
specify trend in # locations (decline, stable, increasing, unknown) :
unknown
are there extreme fluctuations in # locations (>1 order of magnitude)?
unknown
habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat :
apparently stable
Population information
generation time (average age of parents in the population) (indicate years, months, days, etc.) :
unknown
number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values) :
unknown; but at least 8 plants known at time of recent survey (2004)
total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals :
unknown
if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period) :
unknown
are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?
unknown
is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., < 1 successful migrant / year)?
yes
list each population and the number of mature individuals in each :
2 populations: Kamloops (unknown), Penticton (at least 8 plants at time of recent survey in 2004)
specify trend in number of populations (decline, stable, increasing, unknown):
unknown
are there extreme fluctuations in number of populations (>1 order of magnitude)?
unknown
Threats (actual or imminent threats to populations or habitats)
There are no direct or imminent threats. Potential threats included hiking and road building, and collecting of specimens.
Rescue Effect (immigration from an outside source)
does species exist elsewhere (in Canada or outside)?
yes – in California, Eurasia
status of the outside population(s)?
G2 globally
is immigration known or possible?
not likely – the species is extremely rare outside Canada
would immigrants be adapted to survive here?
yes
is there sufficient habitat for immigrants here?
yes
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: D1
Reasons for Designation: In North America, this globally rare moss is known from only three localized sites. Two of these sites are in semi-arid areas of south-central British Columbia. Recent surveys have re-located the species at only one of these. This moss grows on fine soils on the steep portions of silt banks in early stages of plant community development. The extremely small populations render this moss vulnerable to disturbance. Threats include potential road development and maintenance of existing roads, and collecting of specimens.
Applicability of Criteria
Criterion A: (Declining Total Population): Data are not available on population declines.
Criterion B: (Small Distribution, and Decline or Fluctuation): Area of occupancy is less than 1 km² and there are fewer than 5 sites. The Canadian population is severely fragmented. However, data are not available to evaluate declines in habitat or area of occurrence.
Criterion C: (Small Total Population Size and Decline): Not applicable.
Criterion D: (Very Small Population or Restricted Distribution): Meets EN (D1) based on few individuals recorded at Penticton; given the intensity of search effort, it is unlikely that the total number of individuals exceeds 250. May also meet requirements for TH (D2).
Criterion E : (Quantitative Analysis): Not applicable.
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