Small-flowered sand-verbena COSEWIC assessment and status report: chapter 18
Revised Technical Summary
Tripterocalyx micranthus (Torr.) Hook.
Small-flowered sand-verbena – Abronie à petites fleurs
Range of Occurrence in Canada:
Alberta, Saskatchewan
Extent and Area information
extent of occurrence (EO )(km²) :
9.7 km²
specify trend (decline, stable, increasing, unknown) :
Decline (one extirpated population)
are there extreme fluctuations in EO (> 1 order of magnitude)?
no
area of occupancy (AO) (km²)
< 1 sq. km
specify trend (decline, stable, increasing, unknown) :
decline
are there extreme fluctuations in AO (> 1 order magnitude)?
No but visible presence of plants is dependent on degree of precipitation each year
number of extant locations :
8
specify trend in # locations (decline, stable, increasing, unknown) :
decline
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 :
decline in available habitat.
Population information
generation time (average age of parents in the population) (indicate years, months, days, etc.) :
one year (annual).
number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values)
<4000 (3156 counts and estimated)
total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals :
Uncertain (fluctuating numbers)
if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)
are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?
yes
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
- Alberta
- Lower Bow, 789
- Purple Springs, 269
- Grassy Lake, 1797
- N of Medicine Hat, 100 est.
- N of Medicine Hat (Suffield), 100
- Lost River, 100 est.
- Suffield Nat. Wild. Area, 1
- Wolf Island, extirpated?
- Saskatchewan
- 1site, none recently
specify trend in number of populations (decline, stable, increasing, unknown) :
decline
are there extreme fluctuations in number of populations (>1 order of magnitude)?
fluctuation primarily due to dormancy under drought conditions
Threats
- habitat loss due to dune stabilization,
- fire control,
- grazing,
- cultivation,
- industrial activity
Rescue Effect (immigration from an outside source)
does species exist elsewhere (in Canada or outside)?
Western U.S.
status of the outside population(s)?
Kansas (S1), Nebraska (S1), California (S1.3), Wyoming (S3), South Dakota (SH)
is immigration known or possible?
not likely due to disjunction
would immigrants be adapted to survive here?
unknown
is there sufficient habitat for immigrants here?
possibly
Quantitative Analysis
none
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