Small-flowered sand-verbena COSEWIC assessment and status report: chapter 11

Technical Summary

Tripterocalyx micranthus (Torr.) Hook

Small-flowered sand-verbena – Abronie à  petites fleurs

Canada:Alberta, Saskatchewan

Extent and Area information

extent of occurrence (EO) (km²):

9.7 km²

specify trend (decline, stable, increasing, unknown):

decline

are there extreme fluctuations in EO (> 1 order of magnitude)?

presence of occurrences likely vary with climatic conditions

area of occupancy (AO) (km²)

< 1 sq. km

specify trend (decline, stable, increasing, unknown):

decline

are there extreme fluctuations in AO (> 1 order magnitude)?

Major decline.

number of extant locations:

2?

specify trend in # locations (decline, stable, increasing, unknown):

decline

are there extreme fluctuations in # locations (>1 order of magnitude)

?

habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat:

Extreme 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)

  • 1 - Bow Island (2001)
  • 1 - Suffield (1994)

total population trend:  specify declining, stable, increasing or unknown trend in number of mature individuals:

declining

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period):

1000 plant, 1980's to 2 plants, 2001; 99.8% decline

are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?

Requires further study.

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:

  • Bow Island - 1
  • Suffield - 1

specify trend in number of populations (decline, stable, increasing, unknown):

decline

are there extreme fluctuations in number of populations (>1 order of magnitude)?

yes

Threats (actual or imminent threats to populations or habitats) [add rows as needed]

  • 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?

no

would immigrants be adapted to survive here?

unknown

is there sufficient habitat for immigrants here?

no

Quantitative Analysis

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