Climbing prairie rose (Rosa setigera) COSEWIC assessment and status report addendum: chapter 8

Habitat

Habitat requirements

In Canada, Rosa setigera occurs in old fields and shrub thickets, most commonly on sites with moist heavy soils, but occasionally on sandy or shallow soils that dry out during part of the growing season. Climbing prairie rose colonizes open habitats, often in abandoned agricultural fields and vacant urban land. As succession progresses the habitats often become less favourable for this species; senescent individuals can be seen in older shrub thickets. The shifting habitat of this species provides a challenge to making an accurate assessment. With continuing colonization an important factor in maintaining populations on such a landscape, there is a dependence on core populations that can provide abundant seeds for dispersal to new habitats. Very few of these were recorded; they include shrub meadows at Wheatley Provincial Park, St. Clair College prairie, Stone Road Alvar and Rowsoms Conservation Area. There are likely others, such as in the northeastern region of Windsor (Essex Region Conservation Authority [ERCA], 1992) where it is indicated as a common shrub in a few natural areas.

It occurs in areas with a long growing season and a climate moderated by Lake Erie. Seedlings establish in open or thinly vegetated fields and meadows (all observations are by the author unless otherwise referenced).

Trends

A comparison of sites resurveyed in 2000-01 with the earlier records in the 1986 status report and Natural Heritage Information Centre (NHIC) records, reveals a decline of about 38% (about 48% loss and 10% gain) in numbers of known sites, with additional unconfirmed sites near Windsor. Habitat is being lost in urban areas, such as around Windsor, as building development continues in peripheral areas. Succession in shrub meadows also leads to degradation or loss of habitat. However, the species colonizes open habitats so there are likely several unrecorded new sites near core populations. Many habitats are maintained by active management for conservation lands (alvars, prairies and savannahs) in southwestern Ontario, but much of the potential habitat is on the edge of agricultural or developed land that is subject to changes in management and loss of habitat quality.

Protection/ownership

Most of the core populations are under protection; the following have public ownership: Wheatley Provincial Park (provincial); Rowsoms Conservation Area and Hillman Marsh (conservation authority). Stone Road Alvar is owned and managed by the Federation of Ontario Naturalists, Nature Conservancy of Canada and Essex Region Conservation Authority. Walpole Island is managed by the Walpole Island First Nation. About six populations with several individuals each occur on private land around Windsor (ERCA, 1992). Smaller populations occur at Point Pelee National Park (but likely introduced there, V. McKay, pers. comm.) and on other private land.

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