Part 1 COSSARO candidate species at risk evaluation form – June 2010

Cucumber Tree (Magnolia acuminata)

Current designations:

GRANK – G5 (NatureServe, 2010)
NRANK Canada – N2 (NatureServe, 2010)
COSEWIC - Endangered (April 2010)
SARA – Schedule 1, Endangered (Species at Risk Public Registry, 2010)
General Status Canada – At risk (Wild Species, 2005)
ESA 2007 – END (MNR, 2010)
SRANK – S2 (NatureServe, 2010)
General Status Ontario – At risk (Wild Species, 2005)

Distribution and status outside Ontario:

Cucumber Tree occurs thorough the eastern United States from New York, south to northwest Florida and west to Louisiana and Arkansas.

Eligibility criteria

Native status

✔ [yes] The species occurs as a native tree in southern Ontario.

Taxonomic distinctness

✔ [yes] Magnolia acuminata is a distinct taxon.

Designatable units

There is a single designatable unit of this species in Canada. It occurs in two disjunct regions of southwestern Ontario, within the Great Lakes Plains Ecological Area (Carolinian Region), but there are no morphological or genetic differences between populations.

Priority-setting criteria

Recent arrival

✔ [ no] There is no evidence to suggest that this species is a recent arrival in Ontario.

Non-resident

✔ [ no] This species is resident in Ontario.

Primary criteria (rarity and declines)

  1. Global rank

    [Not in any category]. Cucumber Tree is ranked G5. (NatureServe, 2010)

  2. Global decline

    [Not in any category]. There is no evidence of a substantial global decline.

  3. Northeastern North America ranks

    [Not in any category]. Cucumber Tree is present as a native in 11 northeastern North American jurisdictions. It is ranked in 6 jurisdictions (54%), but is ranked secure in 4 of these, and S1 and S2 in only two (18%).

  4. Northeastern North America decline

    [Not in any category]. There are no northeastern North American jurisdictions from which Cucumber tree has been extirpated. Loss of forest habitat has occurred historically, but there is no evidence for a widespread continuing decline.

  5. Ontario occurrences

    ✔ [TH] There are 18 documented occurrences of Cucumber Tree in Ontario (COSEWIC, 2009)

  6. Ontario decline

    ✔ [SC]. The generation time of Cucumber Tree is about 45 years (COSEWIC, 2009). Within the last 2 generations (90 years) there were likely undocumented losses of populations due to logging and land clearing. There may be continued decline in habitat of some sites, but most populations now appear stable.

  7. Ontario’s conservation responsibility

    ✔ [Not in any category]. The range of Cucumber Tree in Ontario comprises <10% of the global range.

Secondary criteria (threats and vulnerability)

  1. Population sustainability

    ✔ [SC]. Some of the Ontario populations are so small that successful recruitment is not occurring.

  2. Lack of regulatory protection for exploited wild populations

    [Not in any category]. Cucumber Tree is not an exploited species. It is listed as Endangered in Canada and Ontario. The species and its habitat are protected under the ESA. Some mature individuals may be lost as a result of logging or alteration of habitat.

  3. Direct threats

    ✔ [SC]. The main threat to Cucumber Tree may be inadvertent logging or land clearing on private land where the trees are not known to occur. Invasive exotics may impede germination and seedling survival. No regeneration is occurring in sites with very small numbers of individuals (7 of 18 = 40% of sites)

  4. Specialized life history or habitat-use characteristics

    ✔ [SC]. Cucumber Tree has a slow maturation rate, it begins flowering at about 30 years (COSEWIC, 2009). The mature trees grow in rich deciduous forests in extreme southern Ontario. Regeneration requires canopy gaps.

COSSARO criteria met (primary/secondary)

[list the number of primary and secondary criteria met in each status category]

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

Summary

This is forest canopy tree that can attain a height of about 30 m. It prefers rich, moist sites, often where there is a mosaic of swamp and upland. It occurs in eastern North America from New York in the north to northern Florida, Louisiana and Arkansas in the south. In Canada it is native to the Carolinian region of Ontario and is restricted to two disjunct areas in Norfolk County and the Niagara Region. There are 18 extant populations known, of which only 4 contain more than 10 individuals. Lone trees will set a few seeds, but seed production is much higher where cross-pollinations can occur. Recruitment has not been observed in 8 sites. The main threat may be inadvertent logging on private and where the location of the trees is not known. Most populations appear to be stable, but habitat loss has occurred throughout the Carolinian Region in Ontario and decline in habitat quality through fragmentation and invasive species is continuing in most sites.

Information sources

Ambrose, J.D. and D. Kirk. 2007. Recovery Strategy for Cucumber Tree (Magnolia acuminata L.) in Canada. Prepared for the Ontario Ministry of Natural Resources by the Cucumber Tree Recovery Team, ⅷ + 24pp. + addenda.

COSEWIC, 2009. Update COSEWIC Status Report on Cucumber Tree (Magnolia acuminate) in Canada. 6 month Interim Report Committee on the Status of Endangered Wildlife in Canada. Ⅳ +18 pp.

COSEWIC 2010. Database of wildlife species assessed by COSEWIC. [http://www.cosepac.gc.ca/]. Accessed April 2010.

MNR, 2010. Ministry of Natural Resources. Species at Risk Website. [/page/species-risk]. Accessed April 2010.

NatureServe 2010. NatureServe Explorer: an Online Encylopedia of Life. [http://www.natureserve.org/explorer/]. Accessed April 2010.

Species at Risk Public Registry, 2010. [http://www.sararegistry.gc.ca/]. Accessed April 2010.

Wild Species, 2005. General Status Search Tool. [http://www.wildspecies.ca/]. Accessed April 2010.

Appendix 1

Northeastern North America rank, status and decline

Province/state Native status Rank
CT N Not Ranked
DE   Not present
IL   Not Ranked
IN N S1 Critically imperiled
IA   Not Present
KY N S5 Secure
LB   Not Present
MA N Not Ranked
MB   Not Present
MD N Not Ranked
ME   Exotic
MI   Not Present
MN   Not Present
NB   Not Present
NF   Not Present
NF   Not Present
NJ   Exotic
NS   Not Present
NY N S5 Secure
NY N Not Ranked
ON N S2 Imperiled
PA N S5 Secure
PE   Not Present
QC   Not Present
RI   Not Present
VA N Not Ranked
VT   Not Present
WI   Not Present
WV N S5 Secure

Occurs as a native species in 11 of 29 northeastern jurisdictions
SRANK or equivalent information available for 6 of 11 jurisdictions = 54%
S1, S2, SH, or SX in 2 of 11 where it occurs = 18%

Part 2 Ontario evaluation using COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – declining population

No (N/A). There is no evidence of a substantial recent decline in Ontario populations. Most land clearing and habitat loss occurred 200 years ago, which is more than 3 generations.

Criterion B – small distribution and decline or fluctuation

Yes (EN; B1,2 a. b(iii)). The Extent of Occurrence is 557 km2 and the Area of Occupancy 60 km2 based on a 2x2 km grid. There are > 10 populations; there are no extreme fluctuations in habitat or number of individuals. There is a decline in the quality, and possibly the quantity of habitat. The population may be severely fragmented since >50% of sites (and thus AO) have fewer than 10 trees and may not be viable.

Criterion C – small population size and decline

No (N/A). There are <2,500, but there is no continuing documented decline.

Criterion D – very small or restricted

Yes (EN; D1). There are only about 140 mature individuals in Ontario.

Criterion E – quantitative analysis

No (N/A). No available information.

Rescue effect

Yes. Immigration is not known, but seeds could be brought across Lake Erie by birds.