BC Conservation Data Centre: Conservation Status Report
Corydalis scouleri
Scouler's corydalis
| Scientific Name: | Corydalis scouleri |
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| English Name: | Scouler's corydalis |
| Provincial Status Summary | |
| Status: | S3S4 |
| Date Status Assigned: | November 30, 2004 |
| Date Last Reviewed: | April 30, 2019 |
| Reasons: | There are about 800,000 plants of Corydalis scouleri with a total cover of about 11 hectares. The 36+ populations are restricted to two river valleys, the Nitinat and Klanawa occurring over a mere 24 square km. Two populations occur in protected areas (a provincial park and an ecological reserve) and many of the populations are within riparian management areas. Twenty percent of the area occupied by Corydalis scouleri occurs within the provincial park. Threats from logging and recreation are likely not severe enough to cause any great damage to the BC populations. Yet, half of the populations may not be viable based on population sizes. This species may be limited in its ability to disperse to other valleys. The restricted extent of occurrence makes it vulnerable to unforseen natural disasters or future escalation of currently limited threats. |
| Range | |
| Range Extent: | A = <100 square km |
| Range Extent Comments: | Corydalis scouleri occurs in the Nitinat and Klanawa River drainages, as well as in the Carmanah valley, over about 71.5 square km. |
| Area of Occupancy (km2): | AD = 1-25 |
| Area of Occupancy Comments: | Corydalis scouleri occupies about 0.11 square km in BC. This is a conservative estimate mainly based on the inventory of Douglas and Smith (2003). This value doesn't include the occurrence in the Carmanah Valley or three other locations N of the Nitinat populations. |
| Occurrences & Population | |
| Number of Occurrences: | C = 21 - 80 |
| Comments: | There are about 36 extant populations for this taxon. Twenty-two sites were documented but plants were also observed between documented occurrences throughout the Nitinat Valley bringing the total to about 36 sites (based on 1 km separation distance). Based on inventory done in 2003, Douglas and Smith (2003), hypothesize that this species will be found in many more sites (at least 100), but they have not yet been documented. In the absense of EO specifications, which may insist on a larger separation distance for a floodplain species that is likely a wide disperser, number of EO's could be less. |
| Number of Occurrences with Good Viability / Ecological Integrity: | U = Unknown |
| Comments: | There may be about 11 viable EO's soley based on population sizes. Other factors used in assessing viability are unknown though many of the plants occur in a provincial park where logging, a potential threat would be excluded. |
| Number of Occurrences Appropriately Protected & Managed: | D = 13 - 40 |
| Comments: | One population is effectively protected in an Ecological Reserve. Another very large population (44,850 plants/2.48 ha.) is within a provincial park where logging activities are not permitted. About 20% of the total occupied area of Corydalis scouleri occurs in the provincial park. Many of the sites are afforded protection by the riparian management zones that have been designated in the watershed. |
| Population Size: | G = 100,000 - 1,000,000 individuals |
| Comments: | 2003 inventory revealed about 800,000 stems. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Widespread, low-severity threat |
| Comments: | All threats are only potential and apparently not severe. Many of the Corydalis scouleri locations occur in riparian strips. A biodiversity management guideline which suggests the creation of riparian reserve zones conceivably could protect populations close to rivers and streams from logging activities. Besides logging, stream enhancement is a potential threat. Excavating along one creek to rehabilitate a road was observed to have reduced a population in 2003. Recreational activity poses another minor potential threat. Streamside areas are desirable for recreation but also habitat for Corydalis scouleri. Another of the sites that was sampled in 2003 that was listed as having poor viability has a trail running through it - this site is also the driest site known. It is not known whether the poor viability is a result of the habitat alteration, but it may be. Bridge and road building or maintenance activities may have destroyed plants in the past during earlier forestry activities but should not be a problem in the future as they have already been established. Therefore, forest harvest appears not to be a direct threat. |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | U = Unknown |
| Comments: | Population trends are impossible to determine due to the lack of information in the few existing historical records. Habitat trend appears to be relatively stable over the last several years that the populations have been observed. |
| Long-Term Trend: | U = Unknown |
| Comments: | No data. |
| Other Factors | |
| Intrinsic Vulnerability: | BC=Moderately vulnerable to not intrinsically vulnerable. |
| Comments: |
This species may be limited in its ability to disperse to other valleys. The restricted extent of occurrence makes it vulnerable to unforseen natural disasters or future escalation of currently limited threats. |
| Environmental Specificity: | C=Moderate. Generalist or community with some key requirements scarce. |
| Comments: | Corydalis scouleri occurs in Alnus rubra stands on alluvial floodplains over 30 years old, but also in predominately Acer macrophyllum, Picea sitchensis, Cornus stolonifera, Populus balsamifera and Rubus spectabilis plant associations. In one location, it occurs in a mixed Tsuga heterophylla-Picea sitchensis stand. |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | The principle means by which Corydalis scouleri is reproducing needs to be ascertained. Pollinators need to be identified and assessed in terms of whether they are a limiting factor. Such information is needed to determine what defines a population of this plant and what reasonable separation distances are between individual populations. Only then will a true number of known occurrences for this species be determined. In the absense of Element Occurrence specifications, a standard distance has been applied to distinguish when one population ends and another starts. Clusters of plants which are separated by 1 km or more are considered distinct under this assumption. It is likely, however as a floodplain species, that Corydalis scouleri disperses much more widely and separation distances are greater and consequently number of occurrences less. Without basic knowledge about its reproduction, it is difficult to assess numbers and viability. |
| Inventory Needs: | Further inventory is still needed in adjacent river drainages. The Nitinat and Klanawa drainages have had fairly extensive surveys in 2000 and 2003 (Douglas and Jamieson 2000; Douglas and Smith 2003). Douglas and Smith (2003) report that it essentially occurs in all Alnus rubra stands on alluvial floodplains over 30 years old. These stands, often of large coverage, are common along most of the creeks and the Nitinat River itself. They feel that they probably sampled less than 50% of all Alnus stands in the valley. Very little of the area on the north side of the Nitinat was explored. In addition, inventory in the Klanawa River valley has been restricted to only several accessible sites. Sampling in the Klanawa River valley and its tributaries likely amounts to less than 10%. They, therefore conclude that it is likely known from many more locations. |
| Stewardship | |
| Protection: | Unknown. It appears that it may not need any further protection since it has coverage in an Ecological Reserve and in a provincial park (where about 20% of its known occupied area occurs). Furthermore, riparian zones where Corydalis scouleri occurs have been buffered during harvesting. |
| Management: | |
| Version | |
| Author: | Penny. J.L. |
| Date: | April 03, 2007 |
| References | |
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British Columbia Conservation Data Centre. Botany Program. 2000. Database containing records of rare plant collections and observations in the province of British Columbia.
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Douglas, G.W., D. Meidinger, and J. Penny. 2002. Rare Native Vascular Plants of British Columbia, 2nd ed. B.C. Conserv. Data Centre, Terrestrial Inf. Branch, Victoria. 358pp.
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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. 2007. Conservation Status Report: Corydalis scouleri. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 5, 2026).