Common hoptree (Ptelea trifoliata) COSEWIC assessment and status report: chapter 11

Technical Summary

Ptelea trifoliata

Common Hoptree – Ptéléa trifolié

Range of Occurrence in Canada:

southern Ontario, Lake Erie shoreline and inland

Extent and Area information

Extent of occurrence (EO) (km²) :

117 km²

specify trend (decline, stable, increasing, unknown) :

Stable

are there extreme fluctuations in EO (> 1 order of magnitude)?

No

Area of occupancy (AO) (km²) :

7.5 km²

specify trend (decline, stable, increasing, unknown) :

Slight decline

are there extreme fluctuations in AO (> 1 order magnitude)?

No

Number of extant locations :

34

specify trend in # locations (decline, stable, increasing, unknown) :

Decline: 3 sites lost in recent years plus 1 loss in the 1970s; 4 new sites, mostly in same range.

are there extreme fluctuations in # locations (>1 order of magnitude)?

No

Habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat :

Declining; shoreline habitat being lost or degraded

Population information

Generation time (average age of parents in the population) (indicate years, months, days, etc.) :

Likely 3-5 years

Number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values) :

920-1025

Total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals :

Decline 

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period) :

43% decline in 17 populations with comparative counts

are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?

No

Is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., < 1 successful migrant / year)?

Total s. Ontario population mostly fragmented between different shore-line sites and islands of Lake Erie

List each population and the number of mature individuals in each :

  • 1. Brantford : 1
  • 2. Port Burwell : 12
  • 3-6. Colchester : 11
  • 8. Cedar Beach : 2
  • 9-10. Malden : 9
  • 11. Hillman Marsh : 28
  • 12. Point Pelee : ~350
  • 14-20. Pelee Island : 245
  • 21. Middle Island : 300
  • 22. Rondeau Provincial Park : 8
  • 23. Erieau Beach : 7
  • 24. Thamesville : 6
  • 25-26. Walpole Island : 2
  • 28-32. Bertie : 17
  • 33-38. not verified : up to 100

specify trend in number of populations (decline, stable, increasing, unknown) :

slight decline, 3 recent losses

are there extreme fluctuations in number of populations (>1 order of magnitude)?

No

Threats (actual or imminent threats to populations or habitats)

  • Land being developed for seasonal housing
  • Intensive beach grooming
  • Cormorant nesting in Erie Islands
  • Twig boring beetle

Rescue Effect (immigration from an outside source)

does species exist elsewhere (in Canada or outside)?

Canada: no
USA: yes.

status of the outside population(s)?

USA: S1-S2 in 5 states, S3 in 1 state

is immigration known or possible?

Not known but possible through fruit dispersal.

would immigrants be adapted to survive here?

Likely if from northern source.

is there sufficient habitat for immigrants here?

Yes, but problem is loss or degradation of habitat.

Quantitative Analysis

  • 3 populations lost in recent years, 6 in decline, 11 stable or increase, 4 new. 
  • Comparative count estimate, all populations: 1982 : ~990-1090;  2000-2002: ~920-1025 
  • No formal estimate of probability of extinction is available.

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