Van brunt’s jacob’s-ladder (Polemonium vanbruntiae) COSEWIC assessment and status report: chapter 4

Distribution

Global range

Van Brunt’s Jacob’s-ladder is endemic to the central Appalachians, in eastern North America (Figure 2). Its range extends from West Virginia, in the south, to the southernmost portion of Quebec and eastern Maine, in the north. The species is sporadic over its entire range and is most frequent in New York State. Over the past ten years, there do not seem to have been discoveries indicating an extension of its range (Thompson, 1991; Sabourin and Paquette, 1992, 1994; NatureServe, 2001).

Figure 2. North American distribution of Polemonium vanbruntiae (one extirpated native historic population inNew Brunswickis not mapped).

Figure 2.  North American distribution of Polemonium vanbruntiae (one extirpated native historic population inNew Brunswickis not mapped).

Canadian range

In Canada, Polemonium vanbruntiae is known to occur only in Quebec at the present time. A historic population (1885) was reported for southwestern New Brunswick at Trout Brook, Charlotte County (Sabourin and Paquette, 1992, 1994; Ministère de l’Environnement du Québec, 2001), but has not been seen since (Hinds, 1986; Blaney, pers. comm., 2001); another population reported for that same region, at Hoyt, Sunbury County, is considered by Hinds (1983) as possibly having been introduced.

In Quebec, the species has been observed in the Bois-Francs and Eastern Townships regions, at the southeastern tip of the province. The currently known populations are located in 3 regional county municipalities (RCM): Arthabaska, Asbestos and Le-Val-Saint-François.

Currently known locations

The Canadian locations of Polemonium vanbruntiae are listed below, with the exact number of populations within each of these locations. Eight extant locations are currently known, with a total of 12 populations. According to the Centre de données sur le patrimoine naturel du Québec, locations (occurrences) must be separated by a minimum distance of 1 kilometre.

  • RCM of Arthabaska
  • Saints-Martyrs: 1 population; last seen on September 11, 2001, by Alain Meilleur.
  • Développement-Boisvert-Est: 3 populations; last seen on November 2, 2001, by Alain Gouge.
  • Développement-Boisvert-Est: 1 population; last seen on June 12, 2001, by André Sabourin and Alain Gouge.

Note: The two latter locations are separated by a distance of 1.5 km.

  • RCM of Asbestos
  • Saint-Adrien: 1 population; last seen on July 12, 2001, by André Sabourin, Denis Paquette and Geoffrey Hall.
  • Saint-Camille: 2 populations; last seen on July 12, 2001, by André Sabourin and Denis Paquette.
  • Ham-Sud: 1 population; last seen on July 12, 2001, by André Sabourin, Denis Paquette and Geoffrey Hall.
  • RCM of Le-Val-Saint-François
  • Stoke River: 2 populations; last seen on July 11, 2001, by André Sabourin and Denis Paquette.
  • Mont-Carrier-Sud: 1 population; last seen on July 11, 2001, by André Sabourin and Denis Paquette.

In 2001, our fieldwork allowed us to discover two new locations in Quebec, those in Saint-Camille and in Ham-Sud. However, as these are located in the Nicolet-Centre River watershed, within the previously known range for the species, they do not represent true range extensions.

Extirpated locations

In Quebec, Polemonium vanbruntiae has not been seen since 1943 in the Arthabaska region, where it no longer appears to be present (Sabourin and Paquette, 1992, 1994). This region is located slightly northwest from the known extant range of the species.

Also, the species has not been seen since 1885 at Trout Lake , in southwestern New Brunswick (Hinds, 1986). However, the status of the species in this region is uncertain, due to a lack of significant research, and it is not clear whether the extant population in Hoyt (Hinds, 1983) is native or introduced. Further research would be needed in that part of the province, especially in the Magaguadovic, Oromocto, Digdeguash and St. Croix watersheds.

The extirpation of populations previously known from Arthabaska and Trout Lake represents a reduction of the global range of the species.

The fieldwork carried out in Quebec on July 4, 2000 (André Sabourin and Alain Gouge) and July 12, 2001 (André Sabourin and Denis Paquette) leads to believe that the Wotton location (Sabourin and Paquette, 1992, 1994) is now extirpated. However, as this population was located within the currently known range, its extirpation does not represent a true range reduction. Also, a small sub-population at Stoke River (ca. 100 plants) seems to be now extirpated. This site was bulldozed and drained in 2002, probably for a future agricultural field (Geoffrey Hall, pers. comm. 2002).

Extent of occurrence

The occurrence of Polemonium vanbruntiae in Canada extends over 644 square kilometres (46 x 14 km), essentially in Quebec. The long-term historic trend associated with this extent of occurrence seems to be one of decline, given the presumed extirpation of the populations in Arthabaska, Quebec, and Trout Lake, New Brunswick.

The actual area of occupancy is much smaller and covers approximately 5.1 ha, in Quebec. The area covered by each location is as follows:

Saints-Martyrs
0.45 ha (150 x 30 m )
Développement-Boisvert-Est
1.5 ha (200 x 30 m; 200 x 30 m; 100 x 30 m)
Développement-Boisvert-Ouest
0.9 ha (300 x 30 m)
Saint-Adrien
1 m 2 (1 x 1 m)
Saint-Camille
1.01 ha (100 x 100 m; 10 x 10 m)
Ham-Sud
0.15 ha (50 x 30 m)
Stoke River
1.1 ha (200 x 50; 50 x 30 m = extirpated in 2002)
Mont-Carrier-Sud
0.02 ha (20 x 10 m)

The current trend associated with the area of occupancy is on the decline. There has been a growth in the area of occupancy, mainly due to the locations discovered in 2001 at Saint-Camille and Ham-Sud (>1 ha), which more than compensate for the loss of the Wotton location, which was very small (<10 ) according to Sabourin and Paquette (1992, 1994), and the loss of a sub-population at Stoke River (0,15 ha) in 2002. Moreover, in 2001, new subpopulations were found at Développement-Boisvert-Ouest, which tripled the area of occupancy known in 1992 (0.3 ha, or 150 x 20 m); at Développement-Boisvert-Est, a third population was identified, the smallest, central one.

However, although there is a current increase in locations, these new sites presumably represent populations that already existed but were not known. With recent losses of sites or part of sites there has been a slight decline in the overall area of occupancy of the species in Quebec.  Declines in occupancy likely are also primarily of historic occurrence following the arrival of the farming and logging industries in the area.

Moreover, no other recent discovery (in the last 10 years) was mentioned by the relevant resource persons, both in Quebec (Couillard, pers. comm., 2001) and in New Brunswick (Blaney, pers. comm., 2001).

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