Pygmy pocket moss (Fissidens exilis) COSEWIC assessment and status report: chapter 11
Technical Summary
Fissidens exilis
Pygmy pocket moss – fissident pygmée
Range of Occurrence in Canada:
Ontario, Quebec
Extent and Area information
extent of occurrence (EO) (km²) :
30,000 km² (estimated from Figure 2)
specify trend (decline, stable, increasing, unknown) :
Stable
are there extreme fluctuations in EO (> 1 order of magnitude)?
No
area of occupancy (AO) (km²) :
<1 km²
specify trend (decline, stable, increasing, unknown) :
Unknown
are there extreme fluctuations in AO (> 1 order magnitude)?
No
number of extant locations :
7
specify trend in # locations (decline, stable, increasing, unknown) :
Unknown
are there extreme fluctuations in # locations (>1 order of magnitude)?
No
habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat :
Not known
Population information
generation time (average age of parents in the population) (indicate years, months, days, etc.) :
Perennial – generation time unknown
number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values) :
One location recorded in 2002 contained three patches totalling 860 cm².
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) :
Not applicable
are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?
Not applicable
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 :
One population has three patches totaling 860 cm².
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)
Human activities, including recreation and conservation management, have the potential to affect the species' survival even at protected sites (as outlined in Habitat Protection / Ownership), particularly if managers are unaware of the species' presence.
Rescue Effect (immigration from an outside source)
does species exist elsewhere (in Canada or outside)?
Yes
status of the outside population(s)?
Unknown
is immigration known or possible?
Unknown
would immigrants be adapted to survive here?
Yes
is there sufficient habitat for immigrants here?
Yes
Quantitative Analysis
Not applicable
Status and Reasons for Designation
Status: Special Concern
Alpha-numeric code: Not Applicable
Reasons for Designation: A moss with a limited distribution in eastern North America, but which is widespread in Europe. Few populations have been documented in Canada, primarily in Ontario where it occurs in heavily populated and developed areas where natural habitats are widely known to be at serious risk. Although cryptic in habit, the species often grows with other small species that have well documented ranges. The species prefers woodlands, where it is usually found on bare clay or disturbed soil. Most locations are in areas benefiting from some level of conservation protection.
Applicability of Criteria
Criterion A (Declining Total Population): Data not available.
Criterion B (Small Distribution, and Decline or Fluctuation): Meets criteria for Threatened B2a (area of occupancy less than 500 km², 7 locations, and the Canadian populations are severely fragmented). However, a decline in habitat or area of occupancy cannot be demonstrated (b).
Criterion C (Small Total Population Size and Decline): Data not available for population size.
Criterion D (Very Small Population or Restricted Distribution): Area of occupancy is less than 20 km², and there are 7 locations in Canada. However, criterion for Threatened D2 is not met because there is no evidence that the species could become Endangered or Extirpated in a short period of time since the locations are spread over a large geographic area, and most of the locations are in areas benefiting from some level of conservation protection.
Criterion E (Quantitative Analysis): Not applicable.