COSEWIC Status Appraisal Summary on the Large Whorled Pogonia Isotria verticillata in Canada – 2011

COSEWIC status appraisal summaries are working documents used in assigning the status of wildlife species suspected of being at risk in Canada. This document may be cited as follows:

COSEWIC. 2011. COSEWIC status appraisal summary on the Large Whorled Pogonia Isotria verticillata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xiii pp.

Production note:
COSEWIC would like to acknowledge Samuel R. Brinker for writing the status appraisal summary on Large Whorled Pogonia, Isotria verticillata in Canada, prepared under contract with Environment Canada. This status appraisal summary was overseen and edited by Jeannette Whitton, Co-chair of the COSEWIC Vascular Plants Specialist Subcommittee, with assistance from Bruce Bennett, Co-chair of the COSEWIC Vascular Plants Specialist Subcommittee, and Erich Haber, past Co-chair of the COSEWIC Vascular Plants Specialist Subcommittee.

For additional copies contact:

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment Canada
Ottawa, ON
K1A 0H3

Tel.: 819-953-3215
Fax: 819-994-3684
Email: COSEWIC/COSEPAC@ec.gc.ca
Website: www.cosewic.gc.ca

Également disponible en français sous le titre Sommaire du statut de l’espèce du COSEPAC sur l’Isotrie verticillée (Isotria verticillata) au Canada.

© Her Majesty the Queen in Right of Canada, 2012.
Catalogue No. CW69-14/2-21-2012E-PDF
ISBN 978-1-100-20246-4

Assessment Summary – November 2011

Common name
Large Whorled Pogonia

Scientific name
Isotria verticillata

Status
Endangered

Reason for designation
This orchid is known historically from only 3 sites in Ontario, but it has not been seen since 1996 despite searches at two of the three previously known sites. The species requires rich, deciduous or mixed, moist forest on sandy soil with abundant humus; this habitat continues to decline in quality due to trampling and exotic plants and earthworms. It is possible that this species may still be extant in Canada since many orchids are known to have long dormancy periods and often occur in very low numbers.

Occurrence
Ontario

Status history
Designated Endangered in April 1986. Status re-examined and confirmed Endangered in April 1998, May 2000, and November 2011.

Isotria verticillata

Large Whorled PogoniaIsotrie verticillée

Jurisdictions: ON

Status category:

Date of last assessment: May 2000

Reason for designation at last assessment: Only three remaining populations, none seen since 1996.

New reason for designation (only if different from above):
This orchid is known historically from only 3 sites in Ontario, but it has not been seen since 1996 despite searches at two of the three previously known sites. The species requires rich, deciduous or mixed, moist forest on sandy soil with abundant humus; this habitat continues to decline in quality due to trampling and exotic plants and earthworms. It is possible that this species may still be extant in Canada since many orchids are known to have long dormancy periods and often occur in very low numbers.

Criteria applied at last assessment: A1c; B1+2abcde+3d; C2a; D1

If earlier version of criteria was applied¹, provide correspondence to current criteria: A2c; B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v); C2a(i); D1

If different criteria are proposed based on new information, provide explanation:
Under criterion B, subcriteria i, ii, iv and v are no longer considered applicable as they require changes in EO, IAO, or numbers of individuals, populations or locations. None of these parameters has changed since the last assessment.
A criteria do not apply as there is no documented decline (numbers remain at zero).
C2 does not apply as a continuing decline is not feasible with no known individuals.

If application of current specific criteria is not possible, provide explanation:

Reason:

Wildlife species:

Explanation:

No additional information since the previous assessment.

Range:

Explanation:

No individuals of this species have been observed in Canada since 1996. The documented range includes just three sites in southwestern Ontario. The IAO is estimated to be 12 km². While some surveys have been conducted for this species, no individuals have been detected.

Population Information:

Explanation:

Recent surveys have not detected any individuals of this species. The species has not been observed in Ontario since 1996. There are three historically documented sites for this species: Backus Woods, Fowlers Pond, and Skunk’s Misery, all in southwestern Ontario. The last observation of the species in Canada was of a single individual at Skunk’s Misery in 1996. Individuals were last observed at Backus Woods in 1990, and at Fowlers Pond by 1996. The Fowlers Pond site was checked systematically from 2000-2005 by Ontario Ministry of Natural Resources staff (R. Gould, pers. comm.). The Backus Woods population was visited in 2009 during vegetation and species at risk surveys. No individuals were detected, though these could have been overlooked due to late survey timing (MMM Group, 2009). No further information is available on the Skunk’s Misery site (White 1998).

It is possible that a small number of individuals remain at one or more of these sites, but they are unlikely to be present in great enough numbers to alter the Endangered status.

Threats:

Explanation:

This species occurs in rich, moist, relatively open, deciduous or mixed forest on sandy soil with thick leaf litter and abundant humus (Klinkenberg 1986). Habitat loss and degradation are probably the primary past and present threats to Large Whorled Pogonia (Jalava et al. 2010). The Fowlers Pond habitat has been flooded by Beaver (Castor canadensis) activity, likely rendering the habitat unsuitable. Soil compaction and excessive trampling at the Backus Woods population may have contributed to the loss of plants. The Skunk’s Misery site was marked for logging in the late 1990s.

The impacts of exotic earthworms were not addressed in the previous assessment and have been identified in the recent draft recovery strategy as a medium-to-high threat, though the actual severity remains unknown because no attempt has been made to document the presence of exotic earthworms at any of the sites yet (Jalava et al. 2010). Exotic earthworms have been shown to reduce the duff and humus layers in northern temperate forests by increasing rates of litter decomposition as well as reducing fungal diversity in the soil, shifting decomposition from fungal-dominated systems to faster, bacterial-dominated systems (Hendrix and Bohlen, 2002; Wardle, 2002; Bohlen et al., 2004; Hale et al., 2005). This is of particular concern considering Large Whorled Pogonia requires substrates with thick leaf litter accumulations and rich humus. As well, Large Whorled Pogonia, like most orchids (McCormick et al. 2004; Shefferson et al. 2005) relies on mycorrhizal associations with soil-inhabiting fungi for successful seedling establishment and overall fitness throughout all life stages. Thus, the survival of Large Whorled Pogonia is likely closely tied to the edaphic requirements of its mycorrhizal host(s). Impacts to the soil fungal community may render Large Whorled Pogonia plants more susceptible to drought or herbivory, as well as reducing seed germination. As well, air- and precipitation-borne nutrient loading (increases in available nitrogen) have been shown to negatively impact on fungal diversity (Arnolds, 1991), and are therefore additional potential threats to the mychorrhizal associations required by Large Whorled Pogonia. Garlic Mustard (Alliaria petiolata) also appears to be a newly identified threat, noted since the May 2000 COSEWIC assessment (Brownell pers. comm. 2011).

Protection:

Explanation:

Large Whorled Pogonia is listed as an endangered species under the Ontario Endangered Species Act 2007, Schedule 1 (ESA, 2007). A recovery strategy has also been drafted and focuses on knowledge gaps and habitat restoration that may favour re-establishment of Large Whorled Pogonia to self-sustaining levels in southern Ontario (Jalava et al. 2010).

Backus Woods is owned and managed by the Nature Conservancy of Canada (Michael Bradstreet, pers. comm. 2011). Fowlers Pond is a Provincial Wildlife Area managed by the Ontario Ministry of Natural Resources. The Skunk’s Misery site is on private land, but the landowner is aware of the species and has supported conservation activities (Jalava et al. 2010).

Rescue Effect:

Explanation:

No additional information or change in rescue effect since previous assessment. The Canadian Large Whorled Pogonia population (if extant) is small, isolated and not contiguous with U.S. populations to the south, and it is unlikely that propagules from elsewhere would become established in Canada. However, orchid seeds are very small and wind-borne, thus, while establishment is highly unlikely, dispersal may still be possible.

Quantitative Analysis:

Details:

No quantitative analysis is available for this species.

Summary and Additional Considerations: [e.g., recovery efforts]

There have been no sightings of Large Whorled Pogonia in Canada since the previous assessment. The last observation was in 1996 at Skunk’s Misery where a single vegetative individual was found (White 1998). The species has not been seen at Backus Woods since 1990 (White 1998). The Fowlers Pond population has also not been observed since 1990 and this site is likely no longer suitable due to beaver activity resulting in flooding (although the site could be restored, it is unknown whether dormant individuals could survive). Despite the lack of observations since 1996, there is uncertainty about whether the species may persist in Canada. Many orchid species are known to undergo prolonged dormancy, and often occur at low densities; thus it is possible that flowering individuals will be rediscovered in Canada. Exotic earthworms, which reduce the duff and humus layers as well as the fungal diversity, are identified as an additional threat to the species in the draft recovery strategy (Jalava et al. 2010). Large Whorled Pogonia re-establishment may require that this threat be mitigated.

¹ An earlier version of the quantitative criteria was used by COSEWIC from October 1999 to May 2001 and is available on the COSEWIC website.

Michael Oldham, Botanist/Herpetologist, Natural Heritage Information Centre, Ontario Ministry of Natural Resources, Peterborough, Ontario.

Ron Gould, Species at Risk Biologist, Ontario Ministry of Natural Resources, Aylmer, Ontario.

Arnolds, E. 1991. Decline of ectomycorrhizal fungi in Europe. Agriculture, Ecosystems and Environment 35: 209–244.

Bohlen, P.J., S. Scheu, C.M. Hale, M.A. McLean, S. Migge, P.M. Groffman and D. Parkinson. 2004. Non-native invasive earthworms as agents of change in northern temperate forests. Frontiers in Ecology and the Environment 2(8): 427-435.

Brownell, V.R. pers. comm. 2011. Email correspondence to B.A. Bennett. January 2011. Species at Risk Branch, Ontario Ministry of Natural Resources.

Endangered Species Act, 2007. Website accessed April 9 2010.

Hale, C.M., L.E. Frelich, and P.B. Reich. 2005. Exotic European earthworm invasion dynamics in northern hardwood forests of Minnesota, USA. Ecological Applications 15(3): 848-860.

Hendrix, P.F., and P.T. Bohlen. 2002. Exotic Earthworm Invasions in North America: Ecological and Policy Implications. BioScience 52(9): 801-811.

Jalava J.V., J. Jones and J.D. Ambrose. 2010. DRAFT recovery strategy for the Large Whorled Pogonia (Isotria verticillata) in Ontario. Ontario Recovery Strategy Series. Prepared for the Ontario Monistry of Natural Resources, Peterborough, Ontario. vi + 8 pp.

Klinkenberg, R. 1986. Status report on the Large Whorled Pogonia (Isotria verticillata) in Canada. Committee on the Status of Endangered Wildlife in Canada. Canadian Wildlife Service. 40 pp.

McCormick, M.K., D.F. Whigham, and J. O’Neill. 2004. Mycorrhizal diversity in photosynthetic terrestrial orchids. New Phytologist 163: 425-438.

MMM Group. 2009. Ecological Inventory of Species at Risk, Vegetation, Insects, Breeding Birds in Backus Woods, Norfolk County Vegetation Survey. Prepared for Earth Tramper Consulting Inc., Long Point Region Conservation Authority, and Ontario Ministry of Natural Resources. 415 pp.

Shefferson, R. P., M. Weiss, T. Kull and D. L. Taylor. 2005. High specificity generally characterizes mycorrhizal association in rare lady’s slipper orchids, genus Cypripedium. Molecular Ecology 14, 613–626.

Wardle, D. 2002. Communities and ecosystems: linking the above-ground and belowground components. Princeton University Press, Princeton, New Jersey.

White, D.J. 1998. Update COSEWIC status report on the Large Whorled Pogonia Isotria verticillata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-6 pp.

Author of status appraisal summary: Samuel R. Brinker

Large Whorled Pogonia Isotrie verticillée

Range of occurrence in Canada: Ontario

^* See definition of location.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as sa 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.

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 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.

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

Data Deficient (DD)***
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.

* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** Formerly described as “Not In Any Category”, or “No Designation Required.”
*** 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.

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