Van brunt’s jacob’s-ladder (Polemonium vanbruntiae) COSEWIC assessment and status report: chapter 5

Habitat

Habitat requirements

In Quebec, our personal observations indicate that Polemonium vanbruntiae is found in moist habitats that are open to semi-open, rarely shady. This species occupies areas subject to seasonal flooding such as marshy alder or willow stands, riparian meadows associated with rivers or streams, wet clearings, and basins or depressions with herbaceous vegetation. The species occasionally escapes from these stable natural environments into successional environments such as waste grounds and old fields with sufficient moisture, or logging road ditches.

These moist habitats are often located near the foot of slopes, in seepage areas, or near rivers. The species tolerates spring or seasonal flooding, but does not tolerate flooding that is permanent or lasts during the whole growing season.

In Quebec, open or semi-open alder stands appear to be the species’ original native habitat. This habitat is relatively specialized. In the United States, Polemonium vanbruntiae is considered a facultative wetland species (FACW), with a 67 to 99% likelihood of occupying moist habitats when it is found in a natural environment (Rhoads and Klein, 1993; Magee and Ahles, 1999). Our personal observations tend to indicate that this is also the case in Quebec, where the species comes very close to being an obligate wetland plant.

In Quebec, Van Brunt’s Jacob’s-ladder is found in environments where the terrain is flat or slightly sloping, even though the species is associated with the Appalachians, a mountainous region. This type of terrain promotes the accumulation of sediments and alluvial deposits that enrich the soils. The foot of slopes and other sites with some sort of seepage or water flow favour the formation of the rich, deep and humid soils that Van Brunt’s Jacob’s-ladder prefers. This substrate generally contains few or no stones.

The Quebec regions where Van Brunt’s Jacob’s-ladder occurs have a cool climate, and the species is found at moderately high elevations, between 205 and 355 metres. Further south, Polemonium vanbruntiae also prefers cool montane climates, and it is found at elevations above 1,200 metres in West Virginia (NatureServe, 2001).

Van Brunt’s Jacob’s-ladder rarely grows on unstable substrates. The only habitats where it grows that may correspond to such environments are forest road ditches; in fact, we saw the plant growing in ditches only at the two Développement-Boisvert locations.

Plant species most frequently associated with Polemonium vanbruntiae and occurring at almost all Quebec locations include: Alnus incana subsp. rugosa, Calamagrostis canadensis, Clematis virginiana, Carex spp., Doellingeria umbellata, Eupatorium maculatum, Salix spp., Spiraea latifolia, and Thalictrum pubescens.

The upper valleys of Nicolet River and its main branches and the Stoke River Valley are critical areas for the survival of Polemonium vanbruntiae in Quebec and in Canada. Although these valleys are already fragmented, the species still occurs in areas that are large enough to support it; however, the farming and logging industries will need to limit their expansion around Jacob’s-ladder sites. It should be noted that these industries are stable or expanding in the Nicolet-Centre and Stoke River Valleys, whereas agriculture is declining in the upper Nicolet River Valley.

Trends

The former extent of the current locations is unknown. The extirpation of the Wotton population, between 1991 and 2000, may be due to the establishment of a Christmas tree plantation. Over the last 10 years, other populations have declined in terms of their number of plants, but not in terms of their area of occupancy. This is the case at Saints-Martyrs, where logging took place, and in the northern part of the Stoke River site, where a field was partially ploughed and mowed.

The Stoke River population is the most threatened of all, but both this location and the Mont-Carrier-Sud location are threatened by agriculture, which could expand and cause the extirpation of both populations.

Potential habitats seem to exist in the neighbouring valleys. The most favourable valleys are those of the Nicolet-Sud-Ouest and Watopéka Rivers, located within the extent of occurrence, and those of the Bécancour, Bulstrode and Saint-François Rivers, located outside the current extent of occurrence.

At the present time, no site is officially protected by a public authority in Quebec.

Protection/ownership

Currently, all Quebec locations of Polemonium vanbruntiae are located on private land.

The northern part of the Développement-Boisvert-Est location was purchased in September 2001 by the Société de conservation des milieux humides du Québec (SCMHQ), a private conservation agency. This purchase was specifically aimed at protecting Polemonium vanbruntiae. The Saints-Martyrs location also benefits from a conservation agreement (Alain Gouge, pers. comm., 2001); this is also the case for the southern and central parts of the Développement-Boisvert-Est location. The former is the most important location, both in terms of number of plants and of occupied surface area, and the Saint-Martyrs occurrence is average in this respect, so that a large proportion of the species’ habitat is already protected, or will likely be in the near future.

Moreover, negotiations are underway or planned for the protection of additional sites (Ms. Line Couillard, Ministère de l’Environnement du Quebec, pers. comm., 2001).

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