COSSARO Candidate Species at Risk Evaluation Form. for. Pitcher s Thistle (Cirsium pitcheri)

Transcription

1 COSSARO Candidate Species at Risk Evaluation Form for Pitcher s Thistle (Cirsium pitcheri) Committee on the Status of Species at Risk in Ontario (COSSARO) Assessed by COSSARO as Threatened February 2011 Final 1

2 PART 1 COSSARO Candidate Species at Risk Evaluation Form February 2011 Current Designations: GRANK G3 NRANK Canada N2 Pitcher s Thistle (Cirsium pitcheri) COSEWIC Special Concern (November 2010) SARA Endangered (Schedule 1) General Status Canada At risk (2005) ESA 2007 Endangered (Schedule 3) SRANK S2 General Status Ontario At risk (2005) Distribution and Status Outside Ontario: This species is a Great Lakes endemic that occurs only on sand dunes along the shorelines of Lakes Huron, Superior and Michigan. In addition to Ontario it occurs in Michigan, Wisconsin, Indiana and Illinois (COSEWIC 2010).. Native Status ELIGIBILITY CRITERIA Yes. The species occurs only along the Great Lakes in Ontario and several adjacent US states (COSEWIC 2010). Taxonomic Distinctness Yes. There are no taxonomic controversies surround this species, which has been consistently classified as Cirsium pitcheri. Designatable Units COSEWIC (2010) considered all Ontario populations as one designatable unit. Gauthier et al. (2010) determined that there is some genetic distinctness of the 1

3 Pukaskwa (Lake Superior) population most likely attributable to geographic isolation and genetic drift. The southern Lake Huron populations were not included in the study. Recent Arrival PRIORITY-SETTING CRITERIA No. The species has long been known to occur in Ontario (COSEWIC 2010). Non-resident No. PRIMARY CRITERIA (rarity and declines) 1. Global Rank TH. The global status rank of Pitcher s Thistle as vulnerable (G3). 2. Global Decline Not in any category. No indication that Pitcher s Thistle has decreased significantly in global range. 3. Northeastern North America Ranks EN. Pitcher s Thistle is ranked S1, S2, or SX in 80% of the 4 northeastern North American jurisdictions where it occurs (Table 1). 4. Northeastern North America Decline Not in any category. No indication that Pitcher s Thistle has decreased significantly in northeastern North America which is the same as the global range. 5. Ontario Occurrences SC. There are 30 element occurrences, all of which are extant (COSEWIC 2010). COSEWIC reports a total population estimate of over 50,000 individuals in Ontario. 6. Ontario Decline Not in any category. The number of known populations in Ontario has increased from 10 to 30 since 2000 (COSEWIC 2010). Twenty-five occurrences in the vicinity of Manitoulin Island are estimated to have a total population of 50,000 plants. The discovery of several new populations in recent years has significantly increased the known population size (COSEWIC 2010). Of the 30 occurrences, 15 are increasing, seven are fluctuating, three are stable and five are significantly declining. 7. Ontario s Conservation Responsibility TH. The Ontario occurrences are believed to comprise 15% of the global population and 2

4 25% of the global geographic range of the species (Jalava 2008). SECONDARY CRITERIA (threats and vulnerability) 1. Population Sustainability Not in any category. Half of the Ontario occurrences show signs of increasing and many of these populations are quite large therefore these populations appear to be sustainable. 2. Lack of Regulatory Protection for Exploited Wild Populations Not in any category. No known harvest in Ontario. 3. Direct Threats Not in any category. Threats to Pitcher s Thistle include succession (dune stabilization and shading by shrubs), invasive plants, trampling by beach users, beach vegetation management, All terrain vehicles (ATVs) and browsing by deer. Shoreline erosion and sand blowouts threaten some populations (COSEWIC 2010). Currently these threats are not severe enough to cause decline at 25% of Ontario sites. 4. Specialized Life History or Habitat-use Characteristics TH. Pitcher s Thistle inhabits active sand dunes along Great Lake shorelines, including several provincially rare community types. It is susceptible to stabilization of dunes through natural succession or climate change (COSEWIC 2010). Pitcher s Thistle is a monocarpic perennial requiring 3 to 11 years to flower, after which it dies. The prolonged non-flowering period make it vulnerable to environmental changes. Recommended Status: Threatened. COSSARO CRITERIA MET (primary/secondary) ENDANGERED [1/0] THREATENED [2/1] SPECIAL CONCERN [1/0] SUMMARY Pitcher s Thistle (Cirsium pitcheri) is Threatened in Ontario. This perennial plant lives as a basal rosette for 3 to 11 years and then dies after flowering once. It is a Great Lakes endemic found on shoreline sand dunes on Lakes Huron and Superior in Ontario. It inhabits a provincially rare habitat (Great Lakes coastal dunes) and its life history is specialized in terms of habitat. Many new populations have been discovered in the vicinity of Manitoulin Island in the past 10 years, substantially increasing the population estimate for the province. Many of these populations show signs of increase. The 3

5 populations outside of Manitoulin are smaller and not faring as well. The reasons for the listing include the vulnerability of populations on shores in Lake Huron and Lake Superior, the specialized life history, and Ontario s conservation responsibility. Information Sources COSEWIC COSEWIC Status Report on Pitcher's Thistle Cirsium pitcheri in Canada. 2-Month Interim Report, September 2010 Jalava, J.V Recovery strategy for Pitcher's Thistle (Cirsium pitcheri) Lake Huron Dune Grasslands in Canada. Species at Risk Act Recovery Strategy Series. Parks Canada Agency, Ottawa. Xi + 38 pp. + appendices. 4

6 Appendix 1 NORTHEASTERN NORTH AMERICA RANK, STATUS AND DECLINE CT DE IL IN IA KY LB MA MB MD ME MI MN NB NF NH NJ NS NY OH ON PA PE QC RI VA VT WI WV S1 S2 S3 S2 S2 Occurs as a native species in 5 of 29 northeastern jurisdictions Srank or equivalent information available for 5 of 5 jurisdictions = 100% S1, S2, SH, or SX in 4 of 5 = 80% 5

7 PART 2 Ontario Evaluation Using COSEWIC Criteria Regional (Ontario) COSEWIC Criteria Assessment Criterion A Decline in Total Number of Mature Individuals N/A. 15 of 30 Populations appear to be increasing and only 5 are showing decline. Ontario population estimate is significantly higher than it was in Criterion B Small Distribution Range and Decline or Fluctuation N/A. EO, if linear shoreline habitat is used, and IAO are both within limits but populations are not severely fragmented and the applicability of number of locations is in doubt; some decline in quality of habitat is on-going but no extreme fluctuations are evident Criterion C Small and Declining Number of Mature Individuals N/A. No continuing decline demonstrated. Criterion D Very Small or Restricted Total Population N/A. Population size is too large and IAO exceeds limits. Criterion E Quantitative Analysis N/A; none conducted Rescue Effect No. Possibly because there are many populations in Michigan however considered unlikely because populations are more than 100 km which is reported as dispersal limit COSEWIC Status: Special Concern 6