BC Conservation Data Centre: Conservation Status Report
Psilocarphus brevissimus var. brevissimus
dwarf woolly-heads
| Scientific Name: | Psilocarphus brevissimus var. brevissimus |
|---|---|
| English Name: | dwarf woolly-heads |
| Provincial Status Summary | |
| Status: | S1S2 |
| Date Status Assigned: | April 30, 2019 |
| Date Last Reviewed: | April 30, 2019 |
| Reasons: | Three occurrences are currently known in B.C., all on a private land. One of the three known occurrences is thought to have good viability. None of the three known occurrences are currently protected. Average population size is estimated to be between 1,000 and 2,500 individuals. Range extent is estimated at 96 ha, and area of occupancy is estimated to be 255 m2, or less than 0.1 km2 (two 4 km2 grid cells). Short-term and long-term trends are unknown. The scope and severity of threats is high, but timing (immediacy) is unknown. |
| Range | |
| Range Extent: | A = <100 square km |
| Range Extent Comments: | The range extent is 0.772 sq km. |
| Area of Occupancy (km2): | AC = 1-5 |
| Area of Occupancy Comments: | Using GIS tools, AOO index value is 2 cells (each 4 sq km) or 8 sq km. |
| Occurrences & Population | |
| Number of Occurrences: | A = 1 - 5 |
| Comments: | Three occurrences are currently known in B.C., all on private ranch land within Agricultural Land Reserve near Princeton (Douglas et al. 2003; Fairbarns 2006; McIntosh 2010). |
| Number of Occurrences with Good Viability / Ecological Integrity: | B = 1 - 3 |
| Comments: | One of the three known occurrences (near Stevenson Lake) is thought to have good viability. The other populations SE of Stevenson Lake and ESE of Tracey Lake were not seen in 2009, even though they were searched for. Estimates of viability are based on population sizes as of 2004 and 2009 (Douglas et al. 2003; Douglas, pers. comm. 2005; Fairbarns 2006; Southern Interior Rare Plants Recovery Implementation Group 2008, McIntosh 2010). Information for other variables that influence population viability is not available. |
| Number of Occurrences Appropriately Protected & Managed: | A = None |
| Comments: | None of the three known occurrences are currently protected, and are not being managed to protect rare plants or their habitats (Douglas et al. 2003; Fairbarns 2006; Southern Interior Rare Plants Recovery Implementation Group 2008). |
| Population Size: | D = 1,000 - 2,500 individuals |
| Comments: | Average population size is estimated to be between 1,000 and 2,500 individuals. Population size in B.C. fluctuates widely, based on annual patterns of precipitation. Since its discovery in B.C. in 1996, the size of the population east of Highway 3 SE of Stevenson Lake has ranged from 700 to 2 million plants (Douglas et al. 2003; Fairbarns 2006). Counts at one of the other two smaller occurrences fluctuated between 300 and 11,500 plants over an 8-year period (Fairbarns 2006). Populations west of Highway 3 at Stevenson Lake, found in 2009, were estimated at over 100,000 plants (McIntosh 2010). |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Substantial, non-imminent threat |
| Comments: | The scope and severity of threats is high, but timing (immediacy) is unknown. Primary threats include coalbed methane extraction, agriculture, livestock trampling, ATV use, changes in hydrology, and property development. The scope of the threat is high because the known area of occupancy is very small, it occurs on private property with no conservation protection, and suitable habitat in the region is scarce and fragmented. The severity of the threat is high because potential impacts will likely destroy habitat, the effects of which will be essentially irreversible or will require long-term recovery (>100 years). The immediacy of the threat is unknown, because the intentions of private landowners is unknown. The private property is in Agricultural Land Reserve (ALR), but this does not necessarily provide long-term protection for the populations because landowners may apply to have the land removed from ALR, although there are no indications that such plans are imminent. Wetland fill, soil removal, and development are permitted on ALR land and pose potential risks to populations. Off-road vehicle use was observed near one population in 2002. Excessive cattle trampling was observed at one population in 1997, 2002, and 2009, and herbicide use also poses a threat (Douglas et al. 2003; Fairbarns 2006; Southern Interior Rare Plants Recovery Implementation Group 2008; Terry McIntosh, pers. comm. March 2010). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | U = Unknown |
| Comments: | Short-term trends are unknown (Fairbarns 2006). Population sizes of this annual herb are strongly tied to annual precipitation patterns, and numbers of individuals may fluctuate widely from year to year (Bauder 2000; Griggs and Jain 1983). Between 1997 and 2002, the size of the population southeast of Stevenson Lake increased from 1000s to 800,000-2,000,000, decreased to ca. 335 plants in the 2003 drought, and increased to ca. 11,775 plants in 2004. The population ESE of Tracey Lake increased from 450 plants in 2003 to ca. 7200 plants in 2004 (Douglas et al. 2003; Douglas, pers. comm.; Fairbarns 2006; Southern Interior Rare Plants Recovery Implementation Group 2008). |
| Long-Term Trend: | U = Unknown |
| Comments: | Long-term trends are unknown (Fairbarns 2006). Psilocarphus brevissimus was not known to occur in B.C. until 1997 (Douglas et al. 1998-2002). It may have been overlooked in the past and trends in population size and area of occupancy are unknown, or it may have established only recently in the province, in which case its population size and area of occupancy may be expanding. |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Comments: | Because this annual species matures quickly, reproduces frequently, and has high fecundity, populations can recover quickly from reduced numbers in drought years. On the other hand, because the B.C. populations are small in number, and disjunct hundreds of kilometres from the nearest population to the south, extirpated populations are not expected to re-establish quickly through natural recolonization (Douglas et al. 2003). |
| Environmental Specificity: | A=Very narrow. Specialist or community with key requirements scarce. |
| Comments: | Psilocarphus brevissimus is a vernal pool specialist (Schlising and Sanders 1982; Keeley and Zedler 1998; Bauder 2000). Vernal pool species are highly restricted and specialized, and occur nowhere else in the landscape. |
| Other Rank Considerations: | When vernal pools are flooded, this species may not be visible. Mature plants are inconspicuous and easily overlooked (Douglas et al. 2003). |
| Information Gaps | |
| Research Needs: | The 2008 multi-species recovery strategy calls for upated updated, reliable information on population trends, population and habitat ecology, viability needs, and protection strategies by 2012 (Southern Interior Rare Plants Recovery Implementation Group 2008). Dormancy and viability of seeds of Psilocarphus brevissimus are critical life history traits, and research will be needed for population viability analyses and assessment of extinction risk. Research is also needed to determine the degree of gene flow between populations in B.C. and the U.S. experimental introductions of the species in suitable habitats also needs to be researched. |
| Inventory Needs: | The most recent inventory was done in September 2009 (McIntosh 2010). Annual monitoring of all sites with Psilocarphus brevissimus is recommended, because large fluctuations in population size can occur from year to year, making it difficult to assess trends based on population numbers in any given year. New mapping is needed to identify additional areas of potential habitat that have not yet been surveyed, or sites where introduction or mitigaton could occur. The 2008 multi-species recovery strategy calls for upated population inventory by 2011, a recovery action plan by 2011, delineation of all occupied habitats, and a reliable determination of population trends, population and habitat ecology, viability needs, and protection strategies by 2012 (Southern Interior Rare Plants Recovery Implementation Group 2008). |
| Stewardship | |
| Protection: | All occurrences of Psilocarphus brevissimus in B.C. need to be protected (Southern Interior Rare Plants Recovery Implementation Group 2008). |
| Management: | Activities that impact soils, vegetation, or hydrology in and around vernal pools should be prohibited, and occurrences should have fenced buffers of at least 100 meters to exclude livestock and ATVs. Where possible, natural fire regimes should be maintained, and herbicides should be used with caution when necessary to control the spread of invasive species. Harvesting or seed collection of native plant species and seeding with non-native species should be prohibited. |
| Version | |
| Author: | Christy, J.A |
| Date: | March 08, 2010 |
| References | |
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Bauder, E.T. 2000. Inundation effects on small-scale plant distributions in San Diego, California vernal pools. Aquatic Ecol. 34: 43-61.
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COSEWIC. 2003t. COSEWIC assessment and status report on the dwarf woolly-heads Psilocarphus brevissimus in Canada. Comm. on the Status of Endangered Wildl. in Can. Ottawa. vi + 19 pp.
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COSEWIC. 2006h. COSEWIC assessment and update status report on the dwarf woolly-heads Psilocarphus brevissimus Southern Mountain population and Prairie population, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 24 pp.
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Douglas, G.W., G.D. Straley, and D. Meidinger, eds. 1998b. Illustrated Flora of British Columbia, Vol. 1, Gymnosperms and Dicotyledons (Aceraceae through Asteraceae). B.C. Minist. Environ., Lands and Parks, Wildl. Branch, and B.C. Minist. For. Res. Program. 436pp.
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Griggs, F.T. and S.K. Jain. 1983. Conservation of vernal pool plants in California. 2. Population biology of a rare and unique grass genus Orcuttia. Biol. Conserv. 27: 171-193.
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Southern Interior Rare Plants Recovery Implementation Group. 2008b. Multi-species recovery strategy for the Princeton Landscape, including dwarf woolly-heads (Psilocarphus brevissimus var. brevissimus), slender collomia (Collomia tenella), and stoloniferous pussytoes (Antennaria flagellaris) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 28 pp.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2010. Conservation Status Report: Psilocarphus brevissimus var. brevissimus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 13, 2026).