Small-whorled Pogonia Evaluation

COSSARO Candidate Species at Risk Evaluation for Small Whorled Pogonia (Isotria medeoloides)
Committee on the Status of Species at Risk in Ontario (COSSARO) Assessed by COSSARO as endangered
June 2011
Final

Part 1 Current status and distribution

Current designations:

GRANK – G2 (Assessed 18/06/2004) (NatureServe, accessed 05/2011)
NRANK Canada – N1 (Assessment date unknown) (NatureServe, accessed 05/2011)
COSEWIC – Endangered (COSEWIC 2011)
SARA – Endangered (Schedule 1) (Environment Canada 2010)
ESA 2007 – Endangered (Ministry of Natural Resources 2011)
SRANK – S1 (NatureServe, accessed 05/2011)

Distribution in Ontario:

This species has only ever been known in Ontario from one site in the Calton Swamp in Elgin County (COSEWIC 2000, 2011).

Distribution and status outside Ontario:

It occurs in eastern North America along the states of the Atlantic seaboard from New England to Georgia and inland to Michigan in the north and Tennessee in the south (NatureServe 2010).

Part 2 Eligibility for Ontario status assessment

2.1 Application of eligibility criteria

Taxonomic distinctness

Yes. There is no doubt of the taxonomic distinctness of this species.

Designatable units

There is only one occurrence of this species in Canada and Ontario, and therefore one Designatable Unit.

Native status

Yes. There is no evidence to suggest that this species is not native to Ontario.

Presence/absence

Present. This has plant only ever been known from one population in Ontario and has not been seen since 1998 in spite of regular monitoring, but the species is known to spend several years without putting up above ground shoots. The probability that the population is still extant after not appearing for so many years is low, but the time is not sufficient (40 years) for the species to be declared extirpated.

2.2 Eligibility results

1. The putative taxon or DU is valid. Yes.
2. The taxon or DU is native to Ontario. Yes.
3. The taxon or DU is present in Ontario, extirpated from Ontario or extinct? Present.

Part 3 Ontario status based on COSSARO evaluation criteria

3.1 Application of primary criteria (rarity and declines)

1. Global rank

Endangered.

2. Global decline

Not in any category. There has been a gradual decline in some populations in the U.S. where there has been long-term monitoring. Sometimes declining populations rebound and dormancy makes it difficult to determine trends. NatureServe (2010, accessed May 2011) lists the Global Short Term Trend as 10-30%.

3. Northeastern North America ranks

Endangered. This plant is tracked in all 16 Northeastern North American jurisdictions where it occurs and is ranked S1, S2, SH or SX in all of them.

4. Northeastern North America decline

Not in any category. The Northeastern North American decline is similar to the global decline since most occurrences are in Northeastern North America.

5. Ontario occurrences

Endangered. There is only one, possibly extant, occurrence for this species in Ontario.

6. Ontario decline

Not in any category. Since this plant has only one occurrence in Ontario, and is not known with certainty to be extirpated, there has been no recorded decline.

7. Ontario’s conservation responsibility

Not in any category. The total estimated global number of populations is about 93 (NatureServe, 2010). Since there is only one population in Ontario, the Ontario portion is little more than 1% of the global population.

3.2 Application of secondary criteria (threats and vulnerability)

8. Population sustainability

Insufficient information. No PVA has been done, but it is unlikely that a single population of a few individuals is sustainable.

9. Lack of regulatory protection for exploited wild populations

Not in any category. There is no exploitation of this species. It is listed as Endangered by COSEWIC and it and its habitat are protected under the provincial Endangered Species Act.

10. Direct threats

Threatened. Trampling by ATVs has damaged populations of this plant in the past. Measures have been taken to prevent a reoccurrence of this event. Exotic earthworms may pose a threat by removal of the duff layer where this plant lives, but this has not been demonstrated.

11. Specialized life history or habitat-use characteristics

Special concern. This species appears to have narrow ecological tolerance and grows in the duff layer of mixed woodlands on acid soil. It is dependent on fungal associations. Like other orchids it can spend several years in a "dormant" or underground state. The species is self pollinated and, unlike some orchids, does not rely on specialized insect pollinators (Mehrhoff, 1983).

3.3 COSSARO evaluation results

1. Criteria satisfied in each status category

Number of primary and secondary criteria met in each status category:

• Endangered – [3/0]
• Threatened – [0/1]
• Special concern – [0/1]

Number of Ontario-specific criteria met in each status category:

• Endangered – [1]
• Threatened – [0]
• Special concern – [0]

2. Data deficiency

No. Although there is little recent data on this species, the existing information is sufficient to assess the species. However, whether or not the species is still extant in Ontario is not known.

3. Status based on COSSARO evaluation criteria

The application of COSSARO evaluation criteria suggests that Small Whorled Pogonia is Endangered in Ontario.

Part 4 Ontario status based on COSEWIC evaluation criteria

4.1 Application of COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – Decline in total number of mature individuals

Not in any category. Possible reduction of >50% based on direct observation (no plants seen since 1998), but 50 years has not passed.

Criterion B – Small distribution range and decline or fluctuation

Endangered B1ab(iii)+2ab(iii) EO < 5,000 km² and IAO < 500 km² and known to exist at < 5 locations. A continuing decline in habitat quality has been observed due to trampling and the presence of exotic earthworms.

Criterion C – Small and declining number of mature individuals

Endangered C2a(i, ii) < 2,500 mature individuals. Continuing decline inferred. No population with >250 individuals, > 95% of individuals in one population.

Criterion D – Very small or restricted total population

Endangered D1 < 250 mature individuals.

Criterion E – Quantitative analysis

Insufficient information. No quantitative analysis has been undertaken, although Ontario population may already be extirpated.

Rescue effect

No. The Ontario population is not contiguous with any U.S. populations and it is unlikely that propagules from elsewhere would become established in Canada. Small Whorled Pogonia is rare throughout its northeastern North American range and populations tend to be small.

Special concern status

No.

4.2 COSEWIC evaluation results

1. Criteria satisfied in each status category

• Endangered – [yes]
• Threatened – [no]
• Special concern – [no]

2. Data deficiency

No.

3. Status based on COSEWIC evaluation criteria

The application of COSEWIC evaluation criteria suggests that Small Whorled Pogonia is Endangered in Ontario.

Part 5 Ontario status determination

5.1 Application of COSSARO and COSEWIC criteria

COSSARO and COSEWIC criteria give the same result. Yes.

5.2 Summary of status evaluation

Small Whorled Pogonia is classified as Endangered in Ontario.

This is a small, perennial small orchid with a single whorl of leaves near the top of the stem beneath the flower. It grows in the duff layer of mesic woodland on acid substrate. It occurs in eastern North America and is rare throughout its range. It is known in Canada and Ontario from only from a single site in Elgin County. It has not been seen since 1998 despite regular monitoring, but is known to have dormant periods of several years and may still be extant. Threats include trampling and exotic earthworms. Because of its global rarity and single population in Ontario with continued threats, and no recent records this species is classified as Endangered.

Information sources

1. Literature cited

COSEWIC 2000. COSEWIC assessment and update status report on the Small Whorled Pogonia Isotria medeoloides in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 6 pp.

COSEWIC. 2011. COSEWIC Status Appraisal Summary on Small Whorled Pogonia Isotria medeoloides in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 9 pp.

Mehrhoff, L. 1983. Pollination in the genus Isotria (Orchidaceae). American Journal of Botany 70(10): 144-1453.

NatureServe. 2010. NatureServe Explorer, An online encyclopedia of life. Isotria medeoloides. http://www.natureserve.org/explorer/. Accessed May 2011.

2. Community and Aboriginal traditional knowledge sources

No sources used for this report.

Appendix 1 Northeastern North America rank, status and decline

Occurs as a native species in 16 of 29 northeastern jurisdictions
SRANK or equivalent information available for 16 of 16 jurisdictions = (100%)
S1, S2, SH, or SX in 16 of 16 = (100%)