Dwarf hackberry (Celtis tenuifolia) COSEWIC assessment and status report: chapter 5

Habitat

Habitat Requirements

In Ontario, this species occurs in two similar types of habitats, 1) dry, sandy sites with open woods near lakeshores of Lake Erie, Lake Huron and slopes above the Trent River: Grand Bend, Point Pelee, Fish Point (Pelee Island) and Stirling Slope; and 2) dry calcareous sites (clay-loam over limestone, i.e., alvars) in open woods: interior Pelee Island, Point Anne and Lonsdale. The sandy soils tend to have a large calcareous component and a pH above 7. The open habitats appear to be early successional woodlands and/or open due to extreme droughty conditions.

In Ontario, the species occurs in dry open woodlands with the following species: Quercus velutina, Q. muehlenbergii, Q. prinoides, Q. rubra, Juniperus virginiana and Rhus aromatica (Klinkenberg, 1984). Wagner (1974) noted the following additional species as associates in Michigan: Carya ovalis, Ceanothus americana, Juglans nigra, Lonicera tatarica, Pyrus coronaria, Pyrus malus, Quercus coccinea, Rhus glabra, and Sassafras albidum.

Trends

There has not been a significant change in the habitats of these specific sites, although some are threatened by expansion of limestone quarrying or sand extraction operations. Similar habitats were surveyed on Pelee Island and the alvar sites of eastern Ontario and some extensions of known populations were found; it is questionable that these are actual population expansions since the last survey--they more likely represent discoveries of previously unknown but well established populations (i.e., Stirling Slope and Lonsdale).

Protection/Ownership

Fish Point and parts of the Grand Bend population are protected as provincial parks; Point Pelee is a national park; part of the Port Franks area of Grand Bend is a Nature Conservancy of Canada nature reserve; parts of the site of the Grand Bend population, inland Pelee Island, Point Anne, Stirling Slope and Lonsdale are privately owned. The expansion of limestone quarry operations in eastern Ontario is reducing potential habitat for this and other significant species.

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