Columbia Quillwort (Isoetes minima): COSEWIC assessment and status report 2019

Official title: COSEWIC Assessment and Status Report on the Columbia Quillwort (Isoetes minima) in Canada 2019

Committee on the status of Endangered Wildlife in Canada (COSEWIC)
Endangered 2019

COSEWIC assessment summary

Assessment summary – May 2019

Common name: Columbia Quillwort

Scientific name: Isoetes minima

Status: Endangered

Reason for designation: This relative of the ferns grows in thin, acidic substrate over steeply sloping bedrock. It occurs in spring ephemeral seepages in otherwise dry coniferous forest glades. A rare Pacific Northwest endemic, the species is known in Canada from four subpopulations in extreme southern British Columbia (Castlegar area), all of which have been discovered since 1996. As of 2017, there were 1,145 plants (1,019 mature) known in Canada. Reductions in habitat quality and quantity have resulted from recreational activities (specifically mountain biking), and from establishment of non-native plants, such as Spotted Knapweed. All Canadian sites are on Provincial Crown Land and where logging of surrounding areas and/or road building activity could change site hydrology with potential negative impacts on this species. Limited genetic diversity is expected in this population.

Occurrence: British Columbia

Status history: Designated endangered in May 2019

COSEWIC executive summary

Columbia Quillwort
Isoetes minima

Wildlife species description and significance

Columbia Quillwort (Isoetes minima) is a perennial fern ally (pteridophyte) and has small, green, simple, quill-like leaves arising from a globose rootstock. The leaves are swollen at the base where the reproductive microspores and megaspores are contained within sporangia.

Distribution

Columbia Quillwort is a globally rare endemic in the Pacific Northwest. In Canada, Columbia Quillwort is known from southern British Columbia in the Monashee and Selkirk Mountains within a 25 km radius of Castlegar. Columbia Quillwort is known in the United States from five sites in Washington, Idaho and Oregon.

Habitat

Columbia Quillwort grows in shallow soil in spring seepage in open, east- to south-sloping glades within forested areas at 700 to 1160 m asl. The plants grow out of thick moss mats or in bare exposed soil.

Biology

Columbia Quillwort leaves emerge in the spring and the lifecycle is closely connected to moisture availability. The plants produce thousands of small microspores and hundreds of megaspores between May and early July. Immature individuals have been noted at all Canadian sites.

Population size and trends

Four subpopulations are known in Canada, all found between 1996 and 2017. In 2017, 1145 plants (including 1019 mature individuals) were counted at four subpopulations.

Threats and limiting factors

All known subpopulations occur on provincial crown land. Logging is planned for the parcel with the two largest subpopulations. Upslope logging and road building may alter hydrologic patterns, impacting downslope seepage and encouraging the spread of non-native invasive plants. The most serious non-native competitor is Spotted Knapweed, which competes with Columbia Quillwort for water and other resources at all sites. More severe droughts associated with climate change may impact on spore production. Shrub and conifer encroachment associated with succession will degrade habitat over time. Recreational activities including mountain biking and hiking may also have negative impacts on Columbia Quillwort plants and their habitat.

Small isolated populations can suffer from limited genetic diversity and inbreeding depression.

Protection, status, and ranks

Columbia Quillwort currently has no legal protection in Canada. In British Columbia, it is red-listed and ranked S1—Critically Imperilled (2015). It is also nationally ranked as Critically Imperilled (N1). All known existing subpopulations occur on provincial crown land.

Technical summary

Scientific name: Isoetes minima

English name: Columbia Quillwort

French name: Isoète du Columbia

Range of occurrence in Canada: British Columbia

Demographic information

Generation time (usually average age of parents in the population; indicate if another method of estimating generation time indicated in the IUCN guidelines(2011) is being used):

5 yrs. Minimum 2 to 3, but average age of mature individuals is likely 5 years.

Is there an [observed, inferred, or projected] continuing decline in number of mature individuals?

Yes, inferred from impact of threats.

Estimated percent of continuing decline in total number of mature individuals within [5 years or 2 generations]:

Not applicable

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over the last [10 years, or 3 generations]:

Inferred stable population

[Projected or suspected] percent [reduction or increase] in total number of mature individuals over the next [10 years, or 3 generations]:

Suspected reduction of 10 to 70% based on impact of threats.

[Observed, estimated, inferred, or suspected] percent [reduction or increase] in total number of mature individuals over any [10 years, or 3 generations] period, over a time period including both the past and the future:

Inferred percent total number mature individuals stable.

Are the causes of the decline a) clearly reversible and b) understood and c) ceased?

Not applicable

Are there extreme fluctuations in number of mature individuals?

No

Extent and occupancy information

Estimated extent of occurrence (EOO):

53 km²

Index of area of occupancy (IAO) (Always report 2x2 grid value):

16 km²

Is the population “severely fragmented” for example, is >50% of its total area of occupancy in habitat patches that are (a) smaller than would be required to support a viable population, and (b) separated from other habitat patches by a distance larger than the species can be expected to disperse

a. No
b. No
Further research is required to determine dispersal mechanisms and distances, in particular long-distance dispersal.

Number of “locations”^* (use plausible range to reflect uncertainty if appropriate):

4
Each subpopulation is a separate location based on a combination of threats.

Is there an [observed, inferred, or projected] decline in extent of occurrence?

No

Is there an [observed, inferred, or projected] decline in index of area of occupancy?

No

Is there an [observed, inferred, or projected] decline in number of subpopulations?

No

Is there an [observed, inferred, or projected] decline in number of “locations”*?

No

Is there an [observed, inferred, or projected] decline in [area, extent and/or quality] of habitat?

Yes, inferred decline in quality and area of habitat.

Are there extreme fluctuations in number of subpopulations?

No

Are there extreme fluctuations in number of “locations”?

No

Are there extreme fluctuations in extent of occurrence?

No

Are there extreme fluctuations in index of area of occupancy?

No

^* See Definitions and Abbreviations on COSEWIC website and International Union for Conservation of Nature (IUCN) (Feb 2014) for more information on this term.

Quantitative analysis

Probability of extinction in the wild is at least [20% within 20 years or 5 generations, or 10% within 100 years]: Calculation not done.

Threats (actual or imminent, to populations or habitats, from highest impact to least)

Was a threats calculator completed for this species? Yes

Overall threat impact of high, based on:

1. Droughts (11.2) – Medium impact
2. Recreational activities (6.1) – Medium to low impact
3. Invasive non-native/alien species (8.1) – Low impact
4. Dams and water management/use (7.2) – Low impact
5. Other ecosystem modifications (7.3) – Low impact
6. Fire and fire suppression (7.1) – Unknown impact

What additional limiting factors are relevant? Small isolated populations can suffer from limited genetic diversity.

Rescue effect (immigration from outside Canada)

Status of outside population(s)?

Rare. Five known subpopulations in Washington, Oregon and Idaho State.

Is immigration known or possible?

Not known, unlikely in short term.

Would immigrants be adapted to survive in Canada?

Yes

Is there sufficient habitat for immigrants in Canada?

Yes

Are conditions deteriorating in Canada?⁺

Yes, inferred decline in quality and area of habitat.

Are conditions for the source population deteriorating?⁺

Unknown

Is the Canadian population considered to be a sink?⁺

No

Is rescue from outside populations likely?

No

⁺ See Table 3 (Guidelines for modifying status assessment based on rescue effect).

Is this a data sensitive species? No

Status history

COSEWIC: Designated special concern in May 2019.

Status and reasons for designation

Status: Endangered

Alpha-numeric codes: B1ab(iii)+2ab(iii)

Reasons for designation: This relative of the ferns grows in thin, acidic substrate over steeply sloping bedrock. It occurs in spring ephemeral seepages in otherwise dry coniferous forest glades. A rare Pacific Northwest endemic, the species is known in Canada from four subpopulations in extreme southern British Columbia (Castlegar area), all of which have been discovered since 1996. As of 2017, there were 1,145 plants (1,019 mature) known in Canada. Reductions in habitat quality and quantity have resulted from recreational activities (specifically mountain biking), and from establishment of non-native plants, such as Spotted Knapweed. All Canadian sites are on Provincial Crown Land and where logging of surrounding areas and/or road building activity could change site hydrology with potential negative impacts on this species. Limited genetic diversity is expected in this population.

Applicability of criteria

Criterion A (Decline in total number of mature individuals): Not met. Available data do not indicate declines and number of mature individuals is considered stable, with a future reduction in mature individuals inferred from a continuing decline in area and quality of habitat.

Criterion B (Small distribution range and decline or fluctuation): Meets endangered, B1ab(iii)+2ab(iii) as EOO and IAO are well below thresholds, there are fewer than five locations, and there is an inferred decline in habitat area and quality due to ongoing threats.

Criterion C (Small and declining number of mature individuals): Although the small population (1,019 mature individuals) is below the threshold for endangered (number of mature individuals <2500), C1 is not applicable as the continuing decline cannot be estimated. Meets threatened C2a(i) as no subpopulation has more than 1000 mature individuals and continuing decline is inferred due to a decline in habitat quality.

Criterion D (Very small or restricted population): Not met. Population exceeds thresholds for endangered D1 and although the IAO is small, the species does not appear to be at imminent risk of becoming extirpated or critically endangered within a relatively short period of time.

Criterion E (Quantitative analysis): Data not available to conduct analysis.

Preface

COSEWIC history

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions (2019)

Wildlife species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special concern (SC)
(Note: Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.)

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at risk (NAR)
(Note: Formerly described as “Not in any category”, or “No designation required.”)

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data deficient (DD)
(Note: Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” [insufficient scientific information on which to base a designation] prior to 1994. Definition of the [DD] category revised in 2006.)

A category that applies when the available information is insufficient (a) to resolve a species’ eligibility for assessment or (b) to permit an assessment of the species’ risk of extinction.

The Canadian Wildlife Service, Environment and Climate Change Canada, provides full administrative and financial support to the COSEWIC Secretariat.

Wildlife species description and significance

Name and classification

Scientific name: Isoetes minima A. A. Eaton
Synonyms: Isoetes howellii var. minima (A.A. Eaton) N. Pfeiff.
Common name: Columbia Quillwort
Common French name: Isoète du Columbia
Family: Isoetaceae

The specific status of Columbia Quillwort has been confirmed by recent DNA analysis and morphological investigations (Taylor et al. 2003; Larsén and Rydin 2016; Pereira et al. 2017).

Morphological description

Columbia Quillwort is among the smallest quillwort species in North America (Taylor et al. 2003). The leaves emerge as a tuft from a corm-like rootstock that has been described as either 3-lobed (Eaton 1898) or 2-lobed (Pfeiffer 1922). The 6 to 12 leaves are round and slender, measuring 0.67 to 0.74 mm in diameter (Eaton 1898). The leaves average 3 to 6 cm long but are sometimes 8 to 10 cm long (Pfeiffer 1922). Its common name is a misnomer based on the observation of immature plants. If there is sufficient moisture available, the leaves can become much larger late in the growing season with maximum height noted as 11 cm (Lomer personal communication 2017), 15 cm (Brunton personal communication 2017) and 20 cm (Batten pers. obs. 2017). The ligules are triangular and slightly elongated (Pfeiffer 1922).

The leaves are swollen at the base where megaspores and microspores are formed within sporangia. Megaspores are spherical and 380 to 400 microns in diameter (Brunton personal communication 2017). The most distinctive features are the short, slender spinules around the equator of the megaspore, which resemble “a ship’s wheel with the spinules for handspikes” (Figure 1) (Eaton 1898; Ceska 2001). Columbia Quillwort has a membrane (velum) covering 60 to 75% of the sporangia (Figure 2) (Eaton 1898; Batten pers. obs. 2017; Brunton personal communication 2017). The minute white 26 to 31 µm microspores are sparsely papillose or spinulose (Eaton 1989) (Figure 3).

Population spatial structure and variability

For Columbia Quillwort, the COSEWIC term “subpopulation” (COSEWIC 2015) corresponds reasonably well to the habitat-based plant element occurrence delimitation standards (NatureServe 2004) where a subpopulation is defined as a group of occurrences that are separated by less than 1 km; or if separated by 1 to 3 km, with no break in suitable habitat between them exceeding 1 km; or if separated by 3 to 10 km but connected by linear water flow and having no break in suitable habitat between them exceeding 3 km. The habitat for Columbia Quillwort is specialized (see below) and it is possible that geographical barriers to movement restrict the distribution.

No other Isoetes species are known to co-occur with Columbia Quillwort, although hybridization with geographically, cytologically (2n=22) and ecologically similar Howell’s Quillwort (I. howellii) is at least possible.

Designatable units

There are no recognized subspecies/varieties or discrete/evolutionarily significant populations to be recognized as designatable units. Columbia Quillwort is considered one designatable unit.

Special significance

Quillworts are an ancient and widespread family of primitive, perennial fern allies. They are a key evolutionary group bridging the gap between non-vascular and vascular plants (Pryer et al. 2001). There are fossil records of Isoetes-like plants that date from the Devonian Period, with modern Isoetes arising in the Jurassic Period (200 to 145 my BP) (Pigg 1992, 2001; DiMichele et al. 2001).

Columbia Quillwort is one of the rarest Isoetes species in the world (Brunton personal communication 2017) and has been designated critically imperilled with a global rank of G1G2, (Natureserve 2017). In Canada, it is at the northern limit of its range.

There is no published information on Aboriginal Traditional Knowledge of this species. It is a small plant with a limited distribution and no obvious medicinal properties or utilitarian purpose and thus may have limited significance to First Nations.

Distribution

Global range

Columbia Quillwort is globally rare with fewer than 10 known subpopulations (Figure 4) (NatureServe 2017). It occurs in British Columbia and adjacent Washington, Idaho and Oregon (NatureServe 2017; University of Washington Herbarium 2017).

Canadian range

In Canada, Columbia Quillwort is restricted to the Selkirk and Monashee mountain ranges in southern British Columbia. It is known from four subpopulations, all within a 25-km radius of Castlegar (Figure 5).

Extent of occurrence and area of occupancy

The extent of occurrence based on a minimum convex polygon around all observations is 53 km². The index of area of occupancy based on a 2 km x 2 km grid over the observations is 16 km².

Search effort

The Canadian population of Columbia Quillwort was first discovered on July 5th, 1996 by Oldriska and Adolf Ceska and at a second site later that year by Hans Roemer (British Columbia Conservation Data Centre 2014b). A third subpopulation was found in 2002 (British Columbia Conservation Data Centre 2016). No other sites were found in 2002 during Botany BC field trips in the area.

All three known subpopulations (Beaverdale Meadow, Lloyd’s Meadow and Fairview Meadow) were surveyed in 2017. An additional subpopulation was found just over 1 km east of Lloyd’s Meadow. Additional sites were found in meadows next to each known subpopulation. Search effort also included surveys in other suitable habitat southwest of Rossland, west of Castlegar, east of Christina Lake and west of Creston but no new subpopulations were found (Figure 6). An area southeast of Montrose, British Columbia next to the Pend D’Oreille River was searched by Dan Brunton in June 2017 but no plants were found (Brunton personal communication 2017). The total search effort included 37.9 km of targeted search (Figure 6) and 57 search hours in potential habitat at a time when Columbia Quillwort is most conspicuous.

Although larger meadows outside the geographic extent were identified on orthophotos, it was not possible to determine if the suitable microhabitat was present at that scale. On-site surveys in some apparently suitable locations did not contain the spring seepage habitat required by this species. The habitat is naturally uncommon within the landscape and is limited to sites with south- to east facing aspect, sustained spring seepage, thin soil, and proper slope within non-forested meadows. Habitat also appears to be restricted to a narrow range of elevation within a narrow geographic area. Predictive habitat mapping has not been done so the amount of potential habitat can not be determined. All glades in the area between known sites were surveyed.

Columbia Quillwort is small and easily overlooked. The plants are only visible during a short portion of the growing season before they are obscured by adjacent vegetation growth and before they wither with summer drought. However, the area has been the subject of previous botanical surveys and the highly specialized habitat is extremely limited in the landscape. It is possible, although unlikely, that additional subpopulations will be found in a wider geographical area.

Habitat

Habitat requirements

In Canada, Columbia Quillwort is found in the Interior Cedar – Hemlock (ICH) biogeoclimatic zone. The habitat is found in small meadows within a larger forested matrix. It is associated with prolonged spring seepages with saturated moss mats. These seepages occur over thin soils that discourage the establishment of larger, more vigorous plants that would compete for light, moisture and nutrients. Habitat in the United States is described as moist draw with seasonal seeps; seasonal seep in open meadow; and damp, bare place on prairie (University of Washington Herbarium 2018).

As with all Canadian Isoetes, Columbia Quillwort typically grows in non-calcareous substrate. Soil depths range from 3 to 7 cm, with depth at one site to 10 to 15 cm. Columbia Quillwort occurs primarily in meadows with full sun but also occurs in smaller glade meadows where there is some shade from adjacent tree cover. Aspect ranges from east to south where sites are free from snow early in the spring. Elevation ranges from 700 to 1160 metres. Elevation of sites in the United States is slightly higher ranging from 1370 to 2299 metres (University of Washington Herbarium 2018).

Vegetation is dominated by bryophytes and forbs. Shrubs are usually absent although may be present at the edges of the seeps. Columbia Quillwort grows primarily in thick moss mats (primarily Philonotis fontana, Niphotrichum elongatum and Bryum weigelii) or in bare exposed soil, usually on the upslope side of exposed rock outcrops (Figures 7 and 8). The plant community changes dramatically through the spring and early summer (Figure 9). Characteristically associated species include Buttercup Suksdorfia (Suksdorfia ranunculifolia), Pretty Shootingstar (Primula pauciflora), False Mermaid-weed (Floerkea proserpinacoides), Dwarf Hesperochiron (Hesperochiron pumilus), Yellow Stonecrop (Sedum stenopetalum), Small-flower Blue-eyed Mary (Collinsia parviflora), and Nuttall’s Larkspur (Delphinium nuttallianum).

Habitat trends

Habitat availability is naturally limited and isolated in the larger forested landscape. Although the species may occur in unsurveyed areas, new habitat is not likely to become available. Ongoing land use changes through land conversion, changes to hydrology and infilling of the meadows through succession will result in a net decrease of available habitat over time. The rate of habitat change over the last 10 years is unknown although encroachment of woody plants into the meadows has been observed during this time and areas next to the open meadows have been logged (Batten pers. obs. 2017).

Biology

Life cycle and reproduction

Columbia Quillwort is a sexual diploid (2n=22 - Taylor et al. 2003) terrestrial species and its lifecycle is closely connected to moisture availability. During the dry season (commencing mid- to late June), the leaves shrivel and dry and the plant persists throughout the fall and winter as a dormant corm-like rootstock beneath the soil surface. The leaves emerge in the early spring, the sporangia develop while the leaves are actively photosynthesizing and mature by the time the leaves die back. Herbarium specimens from Washington note spores on specimens dated from June 25^th to August 17^th (Washington State Herbarium 2017).

Isoetes plants are heterosporous, producing thousands of small microspores and fewer (up to 300) megaspores (Taylor et al. 1993; Ceska 2000). Spores are dispersed when the sporangium is ruptured either by physical impact or when the sporangium decays at the end of the growing season (Engelmann’s Quillwort Recovery Team 2010).

All four subpopulations of Columbia Quillwort in Canada appear to be reproducing because smaller plants presumed to be sporelings were observed at all sites. The small plants had fewer leaves (1 to 4), were smaller in stature and had no obvious sporangia (Maslovat pers. obs. 2017).

Vegetative reproduction is rare and apogamy (development of a sporophyte from the gametophyte without fusion of gametes) is unknown in North American Isoetes species (for example, Brunton and Taylor 1990; Brunton and Britton 1999; Engelmann’s Quillwort Recovery Team 2010).

The age to maturity for Columbia Quillwort is unknown. Observations of 15 North American Isoetes species grown in cultivation show production of sporelings after 2 to 3 years (Brunton personal communication 2017). Although it is unclear if these new plants are produced from spores already in the substrate or from spores produced by the parent plant, the sporelings take about 1 to 2 years to reach the size of their parents (Brunton personal communication 2017).

Although there are no published data on the longevity of Columbia Quillwort, the growth from previous years on rootstocks and the presence of previous years’ megaspores indicate that mature plants persist for several years (Brunton personal communication 2017; Maslovat pers. obs. 2017). Other North American Isoetes species have been maintained in cultivation for at least 20 years (Brunton personal communication 2017). Although data is very limited, the generation time is at least 2 to 3 years, with the mean age of parents more likely 5 years or so.

Physiology and adaptability

There have been no specific studies on the physiology and adaptability of Columbia Quillwort and the following information is from other species within the same genus.

Isoetes employs Crassulacean acid metabolism (CAM) mode photosynthesis which allows photosynthesis at limited CO₂ concentrations and is associated with aquatic habitats (Keeley 1987; Yang and Liu 2015). The closely related Howell’s Quillwort is known to employ this pathway (Keeley 1987) and it assumed that Columbia Quillwort does so as well.

Dispersal and migration

Dispersal mechanisms for Columbia Quillwort are unknown. It is likely that short-distance dispersal occurs when spores are carried downslope in water during spring seepage. Soil erosion and transport on the feet of grazing ungulates or other large mammals are presumed to help terrestrial Isoetes spore dispersal across short distances (Jermy 1990; Troia 2006). Small mammal digging was observed next to one site and this may aid transportation of propagules. It is unknown if birds act as long-distance dispersal vectors via soil or dust attached to feet or feathers.

Suitable habitat is naturally isolated and is separated from other habitat patches by forest, which is the dominant vegetation type. It is unclear if unsuitable intervening forest habitat limits dispersal between habitat patches.

Interspecific interactions

There is no information about interspecific interactions. There was no evidence of grazing on any Columbia Quillwort plants (Maslovat pers. obs. 2017) although other Isoetes species are routinely grazed upon by ungulates and waterfowl (D. Brunton personal communication 2017).

Population sizes and trends

Sampling effort and methods

Previously known subpopulations were surveyed in May 2017 when surrounding vegetation was short and poorly developed and Columbia Quillwort plants were comparatively easy to see. To determine abundance, each mature plant was counted by temporarily marking it with a painted wooden skewer.

Abundance

In 2017, 1145 plants (including 126 smaller sporelings) were counted (Table 1). The plants occur in four distinct subpopulations, each separated by more than one kilometre. One kilometre was recommended as the minimum distance between subpopulations because the species occurs in specific, isolated habitats; therefore, minimum distances between occurrences are more restricted than for other species (see Population spatial structure and variability).

The population is not considered “severely fragmented” as most of the area of occupancy is in habitat patches that are large enough to support a viable population.

Fluctuations and trends

At Fairview Meadow, there were an estimated 100 plants in two sites within 500 m² in 2002 (British Columbia Conservation Data Centre 2016). In 2017, 254 plants were observed but the number of plants cannot be precisely compared over time because of differences in counting techniques and area surveyed.

At Beavervale Meadow, the number of plants was recorded as “many” (60+) tiny plants and (20+) larger plants in 2008 (Brunton and McIntosh 17,243, June 28, 2008 (CAN598102)). In 2017, 69 (including 57 mature plants) were counted in May (Maslovat and Batten 2017) and 75 to 80 (including 60 mature plants) were counted in June (D. Brunton personal communication 2017). Counts by the same observer suggests the Beavervale Meadow site is stable.

Columbia Quillwort is not known to undergo extreme fluctuations. The limited available data (above) suggest that Canadian subpopulations have been relatively stable over the last 10 to 20 years.

Rescue effect

Columbia Quillwort has a limited distribution. The agents and frequency of dispersal are unknown, and it has no obvious means of long-distance dispersal. There are only five known subpopulations in the United States, the closest site being in Okanogan County, Washington State over 90 km away from the closest Canadian subpopulation (University of Washington Herbarium 2017). It is unlikely that there would be short-term rescue from naturally dispersing US populations should extirpation of Canadian populations occur.

Threats and limiting factors

Direct threats facing Columbia Quillwort assessed in this report were organized and evaluated based on the IUCN-CMP (World Conservation Union-Conservation Measures Partnership) unified threats classification system (Master et al. 2012). Threats are defined as the proximate activities or processes that directly and negatively affect the population and result in population decline. Results on the impact, scope, severity, and timing of threats are presented in tabular form in Appendix 1. The overall calculated and assigned threat impact is high. The numbers associated with the threats listed below correspond to IUCN threat numbers and the threat calculator completed for this species.

Threats

11.2 Droughts (medium impact)

Columbia Quillwort requires that moisture be maintained in the soil in the spring and early summer for the megaspores to reach maturity. Premature drought may limit reproductive capability.

6.1 Recreational activities (medium to low impact)

All known subpopulations are publicly accessible. One site (Fairview Meadow) is used for mountain biking and possibly dirt biking. A bike track was observed within several metres of Columbia Quillwort plants and tools for maintaining the trail (a broom and mattock) were found on the property (Maslovat pers. obs. 2017). At the same site, all-terrain vehicles (ATVs) use an old road less than half a kilometre away. There is new housing being built close to this site which could increase recreational use over time. At a second site (Lloyd’s Meadow-east) there was a recently flagged hunting trail which does not appear to be regularly used.

Recreational activities can trample plants and well-worn trails can alter hydrology diverting flow from the sensitive seepage areas. Recreational activities could also introduce and spread invasive non-native plants which may compete with Columbia Quillwort.

8.1 Invasive non-native/alien species (low impact)

The invasive plant Spotted Knapweed is present in large numbers at all Columbia Quillwort sites. Early in the season, Knapweed is small and does not appear to compete directly for light or moisture with Columbia Quillwort plants. However, later in the season Knapweed dominates these sites and may cause premature drying of spring seepages, possibly reducing reproductive success by causing premature fruit abortion. Knapweed may alter dispersal patterns (Lacey et al. 1989). It is unknown if Spotted Knapweed in Columbia Quillwort habitat would cause long-term hydrological changes associated with erosion. The impacts of less abundant invasive plants including Common St. John’s Wort (Hypericum perforatum) on Columbia Quillwort are unknown. The biocontrol beetle, Chrysolina hyperici, was observed feeding on St. John’s Wort at Lloyd’s Meadow (Batten pers. obs. 2017; Ministry of Forests, Lands and Natural Resource Operations 2017).

All known subpopulations of Columbia Quillwort in Canada occur on provincial crown land and all four subpopulations have old logging roads nearby. There is a timber licence on the site that includes two subpopulations and the largest number of plants (Lloyd’s Meadow and Lloyd’s Meadow-east) (Penny personal communication 2017). Fresh timber cruising survey tape was observed in June 2017 (Batten pers. obs. 2017).

Although Columbia Quillwort occurs in forest openings where there is no harvestable timber, machinery in areas adjacent to the meadows could spread non-native invasive plants which might degrade the habitat. It is unlikely that logging and wood harvesting would create potential new habitat through glade creation and shrub suppression; invasion of non-native plants in disturbed areas will likely preclude Columbia Quillwort establishment.

7.2 Dams and water management/use (low impact)

Logging and road building in areas upslope could alter hydrologic patterns and may impact the downslope seepage areas. Machinery in meadow habitats might directly alter waterflow. It is unlikely logging would create new habitat because heavy equipment will likely damage existing seepage areas. The logging company is aware of species at risk in the area and has stated it will design any roads and logging to avoid meadows and changes to hydrology. The company will check with the British Columbia Conservation Data Centre during planning stages (Cordeiro personal communication 2018).

7.3 Other ecosystem modifications (low impact)

The glades where Columbia Quillwort occurs are probably maintained by a combination of fire and thin soils. Historical imagery over the last decade seems to show the meadows getting noticeably smaller as shrubs and trees colonize the edges. Succession in the long-term should be considered a threat because it decreases the available habitat and changes the hydrology on which these plants depend.

7.1 Fire and fire suppression (unknown impact)

Fires are suppressed at all meadow sites but the impact of this is not known. At one subpopulation (Beavervale Meadow), there has been an observed change in structure as shrubs establish over time within the meadow areas, likely due to succession and fire suppression. Shrub growth may eventually shade out Columbia Quillwort and may draw moisture from the spring seeps. Fire may create new habitat through shrub and tree removal provided seepages are present and soils are thin enough to prevent woody plants from growing long enough for Columbia Quillwort plants to establish. Alternatively, fire may degrade habitat by increasing erosion and altering hydrology. It is unclear what the long-term impact of both fire and fire suppression might be on Columbia Quillwort. Increased residential development, may increase fire suppression.

Limiting factors

Small, isolated populations can suffer from limited genetic diversity and inbreeding depression (e.g., Ilves et al. 2003; Reed and Frankham 2003; Leimu et al. 2006; Szczecińska et al. 2016) but there is no evidence on the extent to which these effects are acting upon Columbia Quillwort in Canada.

Number of locations

There are four known subpopulations in Canada, all of which are under threat. Each of the four subpopulations is considered to be a location due to the combination of threats at each. Within each of these subpopulations, the number of sites ranges from 4 to 9.

Protection status and ranks

Legal protection and status

Columbia Quillwort currently has no legal protection or status in Canada. It is not listed under the Convention on International Trade in Endangered Species (CITES), the USA Endangered Species Act, or assessed by the IUCN (IUCN 2017).

Non-legal status and ranks

Provincially, Columbia Quillwort is red-listed and is ranked S1 (critically imperilled) (2015) by the British Columbia Conservation Data Centre (British Columbia Conservation Data Centre 2017). It is ranked S1? in Oregon and S1 in Washington and has not yet been ranked in Idaho (NatureServe 2017). Nationally, in Canada it is ranked N1 (critically imperilled) and in the United States it is ranked N1? (probably critically imperilled). It has a global rank of G1G2 (critically imperilled to imperilled; assessed in 2015) (NatureServe 2017).

Habitat protection and ownership

All four currently known subpopulations are on provincial crown land.

In 1957, Lloyd’s Meadow was designated a Section 17 Designated Use Area held by the British Columbia Ministry of Environment for environment, conservation and recreation (UREP) reserve. This designation is still active (GATOR 2017). The Section 17 reserve creates a “Withdrawal from Disposition” that precludes or prevents the acceptance of crown land applications and disposition of crown land (Ministry of Forests, Lands and Natural Resource Operations 2011). The designation does not preclude timber harvest which is currently planned for this site.

Acknowledgements and authorities contacted

Special thanks from the report writer are extended to Ryan Batten for his enthusiastic and meticulous fieldwork prior to the preparation of this report. His extensive contributions to early drafts of this report were indispensable. The report writer offers her sincere gratitude to Dan Brunton for his keen insight into the Isoetes genus and careful edits of the draft report. The report writer thanks Del Meidinger for his guidance during the preparation of this report and Jenifer Penny, Cassandra Robillard, Adolf Ceska, Frank Lomer, Walter Fertig and Ben Legler for providing information about herbarium specimens and field sites in Canada and the United States. Gratitude is extended by the report writer to Jenny Wu and Rosie Soares for their GIS support and to Carl Taylor for his update on the status of FNA revisions. Invaluable support was provided by Dave Fraser, Neil Jones, Deb MacKillop, Rhonda Millikin, Shelly Pruss and Randal Lake. Their assistance and the support of their agencies is much appreciated.

Authorities contacted

Batten, Ryan. Botanist. Victoria, British Columbia.

Brunton, D. Botanist, Brunton Consulting Services. Ottawa, Ontario.

Ceska, Adolf. Botanist, retired (formerly Royal British Columbia Museum), Victoria, British Columbia.

Fertig, Walter. Washington Natural Heritage Program, Washington Department of Natural Resources. Olympia, Washington.

Fraser, Dave. Unit Head, Species Conservation Science, Ministry of Environment and Climate Change Strategy. Victoria, British Columbia.

Jones, Neil. Scientific Project Officer and ATK Coordinator, COSEWIC Secretariat. Gatineau, Quebec.

Lake, Randal. Head, Conservation and Planning, Environment and Climate Change Canada. Delta, British Columbia.

Legler, Ben. Informatics Specialist, University of Washington, Seattle, Washington.

Lomer, Frank. Associate, University of British Columbia. Vancouver, British Columbia.

MacKillop, Deb. Research Ecologist, Ministry of Forests, Lands and Natural Resources. Nelson, British Columbia.

Millikin, Rhonda. Population Assessment Head, Canadian Wildlife Service. Delta, British Columbia.

Penny, Jenifer. Botanist, British Columbia Conservation Data Centre. Victoria, British Columbia.

Pruss, Shelly. Ecosystem Scientist III, Parks Canada Agency. Fort Saskatchewan, Alberta.

Robillard, Cassandra. Botany Collections Technician, Canadian Museum of Nature. Ottawa, Ontario.

Taylor, W.C. Botanist, emeritus researcher, Smithsonian Natural History Museum. Washington, District of Columbia.

Wu, Jenny. Scientific Project Officer, COSEWIC Secretariat, Canadian Wildlife Service Environment and Climate Change Canada. Gatineau, Quebec.

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Biographical summary of report writers

Carrina Maslovat works as a consultant in plant communities at risk, primarily Garry Oak Ecosystems. She has inventoried rare plants in regional, municipal, federal and provincial parks, finding new subpopulations of species at risk and monitoring rare plant populations’ abundance and vitality over time. She has developed management plans for nature reserves and created Best Management Practices to minimize impact to species at risk. She is the writer of three COSEWIC status reports, two status report updates and several recovery planning documents. Recently, she has been working to restore wetland and upland habitat for species at risk.

Collections examined

Canadian Museum of Nature (CAN): D. F. Brunton and K. L. McIntosh 17, 234, June 28, 2008 (CAN 598102)

Consortium of Pacific Northwest Herbaria (accessed online): Faust 17 to 105; WTU: 387376/WTU-V-004140, collected by K.A. Beck, June 25, 2011; WTU 387452, collected by K.A. Beck, August 17, 2011; WTU: 385650/WTU-V-004236, collected by B. Legler, June 30, 2010; OSC: OSC223664, collected by D. Thomas, July 12, 2009; WS: 119319, collected by W.N. Suksdorf, May 16, 1889.

Department of Agriculture, Ottawa (DAO): No specimens

Royal British Columbia Museum (V): No specimens

University of British Columbia (UBC): UBC:V230715, collected by F. Lomer, A. Ceska, O. Ceska and P. Williston, June 18, 2002; UBC:V240821 (no details); UBC:V240821, collected by F. Lomer, July 4, 2013.

Appendix 1. Threats assessment worksheet

Threats assessment worksheet

Species or ecosystem scientific name:

Columbia Quillwort - Isoetes minima

Element ID:

Not applicable

Elcode:

Not applicable

Date:

25/09/2018

Assessor(s):

Ryan Batten, Carrina Maslovat, Dave Fraser, Del Meidinger, Andy MacKinnon, Bruce Bennett, Jenifer Penny

References:

Not applicable

Assigned overall threat impact:

B = High

Impact adjustment reasons:

Not applicable

Overall threat comments:

Generation time 5 years; three generations = 15 years for assessing severity

Classification of threats adopted from IUCN-CMP, Salafsky et al. (2008).