BC Conservation Data Centre: Conservation Status Report
Polystichum californicum
California Sword-fern
| Scientific Name: | Polystichum californicum |
|---|---|
| English Name: | California Sword-fern |
| Provincial Status Summary | |
| Status: | S1 |
| Date Status Assigned: | September 30, 2008 |
| Date Last Reviewed: | April 30, 2019 |
| Reasons: | Polystichum californicum is known from only one location in B.C. Additional populations almost certainly occur. The single known population suggests that the species may be intrinsically vulnerable due to low dispersal rates or have difficulty becoming established in appropriate habitats. Not currently threatened but potentially intrinsically vulnerable. |
| Range | |
| Range Extent: | A = <100 square km |
| Range Extent Comments: | A single occurrence on Texada Island is known. |
| Area of Occupancy (km2): | AD = 1-25 |
| Area of Occupancy Comments: | Using a standard grid cell of 2km x 2 km, the estimated area of occupancy is 4 square km. |
| Occurrences & Population | |
| Number of Occurrences: | A = 1 - 5 |
| Comments: | A single occurrence has been reported. |
| Number of Occurrences with Good Viability / Ecological Integrity: | B = 1 - 3 |
| Comments: | The population of Polystichum californicum on Texada Island is considered to have good viability as it has been known for over 100 years. |
| Number of Occurrences Appropriately Protected & Managed: | U = Unknown |
| Comments: | No occurrences are known to be protected. |
| Population Size: | A = 1 - 50 individuals |
| Comments: | A single plant has been reported. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Slightly threatened |
| Comments: | Information on threats to the single known occurrence is currently unavailable. Potential threats include inbreeding depression due to a small population size, habitat loss or fragmentation, though development is unlikely (A. Ceska, pers. comm.). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | U = Unknown |
| Comments: | There is insufficient information available to determine short-term trends |
| Long-Term Trend: | FH = Decline of <30% to increase of 25% |
| Comments: | There is insufficient information available to determine long-term trends. However, the population on Texada Island has been known for over 100 years. |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Comments: | Few new populations have been reported over 100 years, suggesting that the species may have difficulty with dispersal or with becoming established in suitable habitat. If it is intrinsically vulnerable in any way, extensive potential habitat will not necessarily signify additional occurrences. |
| Environmental Specificity: | C=Moderate. Generalist or community with some key requirements scarce. |
| Comments: | Throughout its range outside of B.C., Polystichum californicum is considered a versatile species that makes use of almost any habitat and has been found on slopes, dry rocky terrain, by stream banks, vertical cliffs and in partial shade or open areas (Washington Natural Heritage Program 1981). In B.C, the single fern observed in 2008, was found in rock crevice on the lower part of a coastal limestone outcrop exposed to salt spray. |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | A better understanding of habitat requirements, distributional ecology and population characteristics is needed. |
| Inventory Needs: | A directed inventory of rocky cliffs on Texada Island and on adjacent islands, conducted by boat is needed to establish range, and number, size and viability of extant populations. |
| Stewardship | |
| Protection: | |
| Management: | |
| Version | |
| Author: | Donovan, M. |
| Date: | September 29, 2008 |
| References | |
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Washington Natural Heritage Program. 1981. An illustrated guide to the endangered, threatened and sensitive vascular plants of Washington. Washington Natural Heritage Program, Olympia. 328 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. 2008. Conservation Status Report: Polystichum californicum. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 9, 2026).