The reproductive cycle of the black crowberry (Empetrum nigrum L., Ericaceae) was investigated on exposed headlands on the Atlantic coast of Nova Scotia. At the main study site, Gaff Point, aerial photographs revealed a shoreline retreat rate from 1976 to 2011 (ca. 0.3 m.y(-1)), with a threefold increase in the rate of heath area loss in the last 10 years relative to the previous 25 years (1976-2001). Empetrum nigrum produces a large crop of berries and sets up seedlings via three main dispersers (gulls, passerines, and mink) at the sea edge and woodland margin. Laboratory study demonstrated that seed germination was scant and slow in the season of berry production but that it was rapid and substantial (mean 33%-50% from berry or scat) for seeds that incubated overwinter in berry or in scat. The largest seed bank coincides with the site of greatest berry production in the heath, but seedlings were not observed in its mat. Most of the scat rain (77%) is deposited at the shore edge and seedlings here are lost to coastal erosion over-winter. Spruce tree understories are the only safe sites for seedling establishment, and if these juveniles become adults of heathland formed after the death of edge trees, the crowberry has an ontogenetic niche shift adapted to climate change. A preliminary checklist is provided for conservation managers of coastal heaths.
Hill, NM; Vander Kloet, SP; Garbary, DJ
The regeneration ecology of Empetrum nigrum, the black crowberry, on coastal heathland in Nova Scotia
Botany-Botanique