Beach pinweed (Lechea maritima) COSEWIC assessment and status report: chapter 6

Distribution

Global Range

Lechea maritima in the broad sense occurs from New Brunswick to North Carolina, reaching up to about 150 km inland in Massachusetts and New Hampshire, but otherwise occurring almost exclusively along the Atlantic coast. Despite its relatively restricted global range, Lechea maritima is considered widespread and secure (G5, NatureServe 2007). Kartesz (1999) cites Hodgdon (1938) for reports of Lechea maritima var. maritima from Ontario and Quebec, but no such reports are given in that paper and the reports are not considered valid by conservation data centre botanists Michael Oldham (Ontario, pers. comm.) and Jacques Labrecque (Quebec, pers. comm.).

The variety subcylindrica is endemic to the southern Gulf of St. Lawrence, where it has a very limited range on New Brunswick’s eastern coast and Prince Edward Island’s northern shore (Figure 2), over 370 km disjunct from the nearest occurrence of variety maritima in south-central Maine (Magee and Ahles 1999). On Prince Edward Island,


Figure 2: Global range of Lechea maritima

Global range of Lechea maritima.

almost all populations occur within 41 km of shoreline along Malpeque and Cascumpec Bays, with a single occurrence a further 54 km west. In New Brunswick, the northernmost and southernmost occurrences are spread over an 87 km straight-line distance, between Miramichi Bay and Bouctouche Bar.


Canadian Range

When treated as a distinct variety, the Canadian populations are endemic to the southern Gulf of St. Lawrence and only occur on barrier sand dunes along New Brunswick’s eastern coast and Prince Edward Island’s north coast (Figure 3). On Prince Edward Island, almost all plants occur within a 41 km stretch of shoreline along Malpeque and Cascumpec Bays, with a single occurrence a further 54 km west on Tracadie Bay. In New Brunswick, the northernmost and southernmost occurrences are spread over an 87 km straight-line distance, between Portage Island in Miramichi Bay and Bouctouche Bar.


Figure 3: Canadian population sites of Lechea maritima and unoccupied potential habitat sites surveyed during AC CDC and Irving Eco-Centre fieldwork, 2003-06

Canadian population sites of Lechea maritima and unoccupied potential habitat sites surveyed during AC CDC and Irving Eco-Centre fieldwork, 2003-06. Numbers correspond to sites listed in Table 1

Numbers correspond to sites listed in Table 1.

To date, the species has been observed on 11 dune systems in five areas. From these observations, a total of 15 populations are identified, each separated from other occurrences by at least one km of unsuitable habitat. Populations within the identified regions are separated from their next nearest population within a region by no more than 7 km (the two populations on Bouctouche Dune), while each of the five identified regions of occurrence are isolated from any of the other regions by at least 19 km. Table 1 lists the populations and identifies the regions and dune systems with which they are associated. The four populations over roughly 21 km of the Kouchibouguac-Richibucto barrier system in New Brunswick support an estimated 66% of the total population of the species. The other area of extensive occurrence is Prince Edward Island’s Cascumpec-Malpeque barrier system that extends over about 41 km and includes a total of 7 identified populations.

 

Table 1: Sites surveyed for beach pinweed populations. For sites where pinweed was found, the region and dune system are noted
Surveyed Sites Found? Region Dune System
1. Portage Island, NB X Miramichi Bay Portage Island
2. Fox Island, NB X Miramichi Bay Fox Island
3. South Kouchibouguac Dune, NB X Kouchibouguac-Richibucto South Kouchibouguac
4. North Richibucto Dune, NB X Kouchibouguac-Richibucto North Richibucto
5. South Richibucto Island, NB X Kouchibouguac-Richibucto South Richibucto
6. South Richibucto Dune, NB X Kouchibouguac-Richibucto South Richibucto
7. Bouctouche Dune, north section, NB X Bouctouche Bouctouche
8. Bouctouche Dune, south section, NB X Bouctouche Bouctouche
9. Cascumpec Sandhills, PE X Cascumpec - Malpeque Bays Cascumpec Sandhills
10. Conway Sandhills, north section, PE X Cascumpec - Malpeque Bays Conway Sandhills
12. Conway Sandhills, south section, PE X Cascumpec - Malpeque Bays Conway Sandhills
13. Hog Island, north section, PE X Cascumpec - Malpeque Bays Hog Island
14. Hog Island, southern section, PE X Cascumpec - Malpeque Bays Hog Island
15. Cabot Beach Provincial Park, PE X Cascumpec - Malpeque Bays Cabot Beach–Darnley
16. Blooming Point, PE X Tracadie Bay Blooming Point
17. Grande Plaine, NB      
18. Chiasson Lighthouse, NB      
19. Île-au-Cheval, NB      
20. Neguac Dune, NB      
21. Preston Beach, NB      
22. Escuminac Beaches, NB      
23. North Kouchibouguac Dune, NB      
24. Chockpish Beaches, NB      
25. Cocagne Island, NB      
26. Shediac Island – Grande Digue, NB      
27. Cap-Brûlé – Cap-Bimet, NB      
28. Aboiteau Provincial Park, NB      
29. Grants Beach, NB      
30. Cape Jourimain Natl. Wildlife Area, NB      
31. Cedar Dunes, PE      
32. Campbells & Cousins Ponds, PE      
33. Cavendish Beach, PE      
34. Rustico Island, PE      
35. Brackley Beach, PE      
36. Deroche, PE      
37. Crowbush, PE      
38. Cable Head, PE      
39. Black Pond, PE      
40. Basin Head, PE      

Sites are mapped in Figure 3. Note that there is no site number 11 because it was combined with site 10.

Extent of Occurrence, calculated as the distance between northern and southern New Brunswick populations plus distance between eastern and western Prince Edward Island populations, is 176 km2. Using a 1 x 1 km grid, Area of Occupancy is 71 km2. Using a 2 x 2 km grid, 38 grid squares are occupied yielding an Area of Occupancy of 152 km2. The actual land area occupied by plants is under 5 km2.

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