Dwarf hackberry (Celtis tenuifolia) COSEWIC assessment and status report: chapter 12

Technical Summary

Celtis tenuifolia

Dwarf hackberry – micocoulier rabougri

Range of Occurrence in Canada:

Ontario

Extent and Area Information

Extent of occurrence (EO) (km²)

Based on polygon around sites, excluding the large area between the southwestern and eastern Ontario populations. <5000 km²

Specify trend in EO :

Stable

Are there extreme fluctuations in EO?

No

Area of occupancy (AO) (km²)

Based on an approximation of habitats occupied. <20 km²

Specify trend in AO :

Stable

Are there extreme fluctuations in AO?

No

Number of known or inferred current locations :

6

Specify trend in # :

increase, but likely reflecting old populations not previously known vs. expansion

Are there extreme fluctuations in number of locations?

No

Specify trend in area, extent or quality of habitat :

Stable

Population Information

Generation time (average age of parents in the population) :

several decades

Number of mature individuals :

893 (based on counts and additional estimates)

Total population trend: Stable

% decline over the last/next 10 years or 3 generations.

N/A

Are there extreme fluctuations in number of mature individuals?

No

Is the total population severely fragmented?

Ontario populations and others at northern range widely separated

Specify trend in number of populations :

Slow increase based on new discoveries of old sites

Are there extreme fluctuations in number of populations?

No

List populations with number of mature individuals in each:

  • Pelee Island: 5
  • Point Anne: 2
  • Point Pelee: 136
  • Sterling Slope: 24
  • Ipperwash-Pinery: 724
  • Lonsdale: 2

Threats (actual or imminent threats to populations or habitats)

  • Bark beetles (10% mortality/year: Dunster, 1992).
  • Loss of habitat through limestone quarrying, sand extraction and cottage development.

Rescue Effect (immigration from an outside source)

Status of outside population(s)?

USA: Imperilled, vulnerable to apparently secure.

Is immigration known or possible?

Possible, via migratory birds

Would immigrants be adapted to survive in Canada?

Yes, if from northern populations

Is there sufficient habitat for immigrants in Canada?

Yes

Is rescue from outside populations likely?

Possible but unlikely

Quantitative Analysis

N/A

Current Status

COSEWIC: Threatened

Status and Reasons for Designation

Status: Threatened   

Alpha-numeric code: Met criteria for Endnagered, B1ab(iii,v)+2ab(iii,v) but was designated Threatened, B1ab(iii,v)+2ab(iii,v); C2a(i)’ D1_2. because it is not at imminent risk of extirpation.

Reasons for Designation: A shrub of dry sandy or calcareous alvar woodlands habitats found at only six disjunct and fragmented sites adjacent to the Great Lakes. Fewer than 1000 plants have been documented. Threats include potential loss of habitat due to quarrying operations and sand pit expansion in eastern Ontario sites and significant losses in some years due to beetle infestations.

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