BC Conservation Data Centre: Conservation Status Report
Hosackia pinnata
bog bird's-foot trefoil
| Scientific Name: | Hosackia pinnata |
|---|---|
| Scientific Name Synonyms: |
Lotus pinnatus
|
| English Name: | bog bird's-foot trefoil |
| English Name Synonyms: |
bog bird's-foot lotus
|
| Provincial Status Summary | |
| Status: | S2? |
| Date Status Assigned: | April 30, 2019 |
| Date Last Reviewed: | April 30, 2019 |
| Reasons: | The viability of L. pinnatus in BC is a concern due to the small number of known populations, habitat specificity, isolation from populations in adjacent jurisdictions, limited seed dispersal and the lack of protection on private land. Alterations to site hydrology and erosion arising from intensive recreational use of primary habitat by off-road vehicles also threaten the persistence of populations of L. pinnatus in BC. Significant losses of individuals and habitat are anticipated if the commercial development of the site supporting the largest population proceeds as planned. |
| Range | |
| Range Extent: | A = <100 square km |
| Range Extent Comments: | In BC, Lotus pinnatus is known from 5 extant localities within a small area on the east coast of Vancouver Island near Nanaimo, BC. The range extends from Harewood Plains, south of Nanaimo to the Woodley Range Ecological Reserve, northeast of Ladysmith and to Gabriola Island, east of Nanaimo. |
| Area of Occupancy (km2): | AC = 1-5 |
| Area of Occupancy Comments: | The known area of occupancy (AO) is < 1 ha. Although the area of occupancy is restricted due to the limited availability of preferred habitat (i.e. open seepages at the edge of grassy meadows), it is possible that additional populations of L. pinnatus remain to be discovered. With the exception of Harewood Plains, most sites contain few individual plants. |
| Occurrences & Population | |
| Number of Occurrences: | A = 1 - 5 |
| Comments: | There are 5 known populations of Lotus pinnatus in BC. Historic populations at two other sites could not be relocated in 2003 and are likely extirpated. |
| Number of Occurrences with Good Viability / Ecological Integrity: | B = 1 - 3 |
| Comments: | The minimum viable population size is unknown for L. pinnatus. Therefore, it is difficult to assess the quality of the small populations. The only large population is at Harewood Plains. The subpopulations at this location are at risk of habitat loss and degradation resulting from road construction/maintenance, residential development, intensive use of recreational off-road vehicles and competitive exclusion by native and non-native vegetation. |
| Number of Occurrences Appropriately Protected & Managed: | B = 1 - 3 |
| Comments: | Four occurrences are located on land that is privately owned, where the level of protection is unknown; one site is protected within Ecological Reserve #142. |
| Population Size: | D = 1,000 - 2,500 individuals |
| Comments: | The total number of plants in Canada is between 1500 and 2000. The clumped sprawling habit of L. pinnatus makes it difficult to identify separate individuals and counting methods have varied with different investigators. Until counting methods are standardized, population numbers should be considered rough estimates. On average, each individual includes from 3 to 5 shoots. The inventory for the purposes of the COSEWIC status report involved a count of all stems at each site. Each site was surveyed by walking a series of transects and counting individual stems, where practical. At Harewood Plains, a grouping method was used to estimate the number of stems and simplify counting (Donovan, 2003). |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Substantial, imminent threat |
| Comments: |
The primary threat to L. pinnatus in BC is habitat loss from urban and residential expansion. Approximately 25 - 30% of the plants at Harewood Plains, the site of the only large population of this species in Canada, is under application for a development permit for a trailer park. The construction and maintenance of logging and utility access roads at Harewood Plains also poses a real and immediate threat to L. pinnatus habitat. The populations at Harewood Plains and White Rapids Road are also under direct and immediate threat of habitat degradation from intensive use of recreational off-road vehicles. Root systems may be damaged or destroyed through compaction and in areas where the vehicles enter the seepages, plants have been damaged and populations have become partitioned. In some areas at Harewood Plains, the thin and fragile soils have been rutted to bedrock and plants have been dislodged onto bare rock where they cannot re-establish. Despite efforts by the property managers to exclude recreational off-road vehicles (i.e. by installing cement barriers along the access road), vehicles continue to access Harewood Plains on a regular basis and the potential for further impacts is high. Hydrological disruptions that modify groundwater flow also threaten the long-term survival of this species. |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | F = Decline of 10-30% |
| Comments: | The short-term trend over the last 10 years in total population, number of extant locations and area of occupancy is a decline. In the absence of some form of management, continued habitat loss and degradation is likely. There are no existing sites where the habitat is not degraded and introduced species are not a significant component of the vegetation. Little is known of demographic characteristics and population trends due to a lack of long-term monitoring, though the number of individual plants appears to have increased at one site, on Gabriola Island. However, estimates of population trends in L. pinnatus are currently unreliable as the clumped, sprawling habit makes it difficult to identify separate individuals and counting methods have varied with different investigators (Donovan, 2003). |
| Long-Term Trend: | E = Decline of 30-50% |
| Comments: | Though long term trends are difficult to assess, habitat loss and continued decline through habitat conversion for residential and other development in the area is likely, without some form of protection and management. Although adequate long-term population information is lacking, the existence of collections from as early as 1939 indicate that L. pinnatus has been established in and around Nanaimo for at least 60 years. There is no evidence to indicate that L. pinnatus was ever abundant or widespread on Vancouver Island, but it is possible that the extant populations represent historical remnants of a more contiguous distribution along the southeastern portion of Vancouver Island and the Gulf Islands (M. Fairbarns, pers. comm. 2004). |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Comments: | The seeds of Lotus pinnatus lack any strong adaptations for long-distance dispersal by wind or animal vectors. Most seeds are gravity-dispersed and generally land in the immediate vicinity of the parent plant. The plant's habitat along stream channels may permit the legumes and seeds to be transported by water during times of seasonal flooding but germination and seedling survival appears to depend upon continuous surface moisture and the species appears to be a relatively weak competitor with native shrub species or with invasive exotic plants. Competitive exclusion by native and non-native vegetation represents a significant ongoing threat to L. pinnatus, at all sites. Secondary succession associated with fire suppression has the potential to permanently alter the structure and composition of habitat currently occupied by the species and may prevent this species from occupying new sites. There are no existing sites where introduced species are not a significant component of the vegetation (Donovan, 2003). |
| Environmental Specificity: | B=Narrow. Specialist or community with key requirements common. |
| Comments: |
The specific habitat requirements of L. pinnatus, though not definitively known, indicate relatively restrictive conditions for the establishment, growth and dispersal of this species. The localized nature of available habitat is thus a strong limiting factor within the currently known range of Lotus pinnatus (Donovan, 2003). |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | A better understanding of the L. pinnatus community and population ecology will permit more effective management of existing occurrences so that the survival, reproduction and recruitment of individual plants is encouraged. Quantitative monitoring and/or demographic studies should be undertaken to determine both typical short-term and longer-term population trends. Effective management and conservation of the species will require experimental, quantitative field studies that investigate demography, population dynamics, competitive interactions and the effects of soil disturbance and fire management. Before recovery habitat can be identified, a population viability analysis should be performed in order to obtain an estimate of minimum viable population size. Establishment of a seed bank and controlled propagation programs will also improve options for re-establishment of the species in the event of catastrophic population loss or destruction of existing habitat (Miller, 2005). |
| Inventory Needs: | Monitoring protocols need to be developed in consultation with willing landowners and any conservation agreements or easements should include provisions for regularly scheduled monitoring. Activities and other events that appear to threaten either plants or habitat should be recorded and reported to the appropriate landowners or land managers (Miller, 2005). |
| Stewardship | |
| Protection: | Currently, there is no legislation protecting Lotus pinnatus in BC. While the population located in the Woodley Range ER is protected, to a certain extent, only 7% of the total Canadian population is present at this site. Plants at this location are vulnerable to adjacent land uses including ATV use, logging and other land clearing activities. Protecting and securing currently-known occurrences is essential to the conservation and recovery of the species. Practical methods for ensuring this protection include a) acquisition of land supporting the species by public agencies or private organizations with formal committments to conservation, b) the development of stewardship agreements or conservation covenants/easements with involved landowners and c) legislative protection through the Community Charter Act (2003) or the Wildlife Amendment Act (2004) (Miller, 2005). |
| Management: | Threats to all currently occupied sites should be assessed and site-specific management plans should be developed and implemented to reduce threats and restore habitat. Information gained during monitoring and research should be used periodically to update and modify the site management plans. Involving landowners/managers in habitat management is crucial to long-term species protection. Landholders should be encouraged to collaborate with researchers, participate in restoration projects and support species at risk monitoring (Miller, 2005). |
| Version | |
| Author: | Donovan, M. |
| Date: | November 21, 2005 |
| References | |
| No references available | |
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. 2005. Conservation Status Report: Hosackia pinnata. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 8, 2026).