|16. Chickadee Notes|
Rare Arctic Plants in Southeastern New Brunswick
Tucked into the hills of Albert County in southeastern New Brunswick there is an outpost of arctic flowering plants far removed from their geographical strongholds in the Canadian north. The species assembled at this one locality - a gypsum cliff and adjacent talus slope near Albert Mines - are vestiges of a type of vegetation which prevailed over much of the province as the last Ice Age drew to a close between 13,000 and 10,000 years ago. Most notable among these plants are White Mountain Avens (Dryas integrifolia), Myrtle-leaved Willow (Salix myrtillifolia), Mountain Goldenrod (Solidago multiradiata) and Northern Anemone (Anemone parviflora). White Mountain Avens and Myrtle-leaved Willow are unknown elsewhere in the Maritime Provinces. What characteristics do these species have in common which might account for their isolated occurrences near Albert Mines? Do the growing conditions at this locality in some way resemble those in the arctic? When and by whom were these species discovered here and what is the current status of their populations? Is anything being done to protect them? Some of these questions have straightforward answers, some continue to keep research scientists happily occupied, and some have conservationists on their toes.
White Mountain Avens is a common pioneer species on rocky, frost-heaved, treeless tundra throughout the Canadian arctic, extending to northernmost Ellesmere Island at 83sn. A member of the rose family, it is a deeply rooted woody perennial which forms extensive low mats. Its small leathery leaves are a deep lustrous green on the upper side and covered underneath with a nap of chalky-white hairs. In the New Brunswick plants, the creamy white flowers appear in late May or early June, soon developing into heads of long-plumed seeds which are carried away on the wind. The roots of this and other Dryas species, like those of legumes and alders, bear tiny nodules which contain bacteria capable of converting free nitrogen from the air into a form (nitrate) usable by the plant. This gives an important ecological advantage to Dryas plants on tundra soils, where nitrates essential to growth are otherwise in short supply.
Myrtle-leaved Willow is the rarest of the 15 willow species native to New Brunswick. It is a low shrub, not exceeding a meter in height, with elliptic dark green leaves. At its Albert County locality, it occurs both on gypsum talus and in nearby woods. It is mainly a plant of northwestern North American peatlands, lake margins and river banks, ranging eastward to Hudson Bay, but with a few outlying occurrences on limestone and gypsum rocks in the Atlantic region: Table-topped Mountain in the GaspŽ Peninsula, Anticosti Island, northwestern Newfoundland, and near Albert Mines.
Northern Anemone ranges from Siberia and Alaska to Newfoundland, south to Colorado in the Rocky Mountains. In the east it occurs southward to the GaspŽ Peninsula, and in New Brunswick along the shores of the Restigouche River and near Albert Mines. It grows on calcareous soils, often on streambanks, producing rosettes of three-parted leaves and solitary flowering stems from a horizontally creeping rootstock. What appear to be petals in the flowers of anemones are actually coloured sepals. It is this characteristic which distinguishes anemones from their close relatives, the buttercups, most of which have yellow petals and green sepals.
At 10 to 30 cm in height, Mountain Goldenrod is a dwarf among the 17 species of goldenrods, known to occur in New Brunswick. Apart from its small population near Albert Mines, which may consist of fewer than 100 plants, its only other occurrences in the Maritime Provinces are in northern Cape Breton and on nearby St. Paul Island. Its overall range is similar to that of Northern Anemone, although Mountain Goldenrod is more common in western Newfoundland. These plants do not reach high arctic latitudes like White Mountain Avens.
If a general pattern emerges from the geographical distribution and ecology of these species it is, first, that all four have broad subarctic to arctic North American ranges, extending southward in the mountains of the west and east. And second, all occur on calcareous soils in open habitats. Interestingly, all but Mountain Goldenrod are part of another isolated assemblage of arctic species occurring on the north shore of Lake Superior.
Shepherdia or Soapberry (Shepherdia canadensis) is another uncommon plant found on gypsum near Albert Mines and ranging northward into the subarctic. Elsewhere in the province, it is restricted mainly to limestone bedrock on the banks of the upper St. John and Restigouche Rivers and along Chaleur Bay. Shepherdia and Mountain Avens were the first of the gypsum outcrop plants to be discovered near Albert Mines, where they were found in 1942 by Raymond P. Gorham, a New Brunswick entomologist. In 1964, Patricia Roberts, a botanist then at the University of New Brunswick, added Northern Anemone, Myrtle-leaved Willow, and Mountain Goldenrod to the list of rare species occurring here.
The key to understanding the concentration of rare arctic species at this isolated locality is found in sediments on the bottom of southern New Brunswick and other Maritime Provinces lakes. These unconsolidated deposits contain pollen grains and remains of leaves, twigs, fruits, and seeds which provide a partial record of the change in vegetation following the retreat of glacier ice from the region beginning about 13,000 years ago. This evidence reveals that arctic tundra prevailed over large parts of the Maritimes during the transition from glacial to postglacial conditions. One of the common species in this treeless vegetation type was White Mountain Avens. It and other tundra plants such as Alpine Blueberry (Vaccinium uliginosum) and Shrub Birch (Betula glandulosa) are represented by abundant fragments preserved in roughly 10,000 to 12,000 year-old lake sediments near the Bay of Fundy and elsewhere in the Maritimes. The latter two species are presently found in New Brunswick only on a few northern mountain summits and bogs. Similar evidence indicates that Shepherdia was also more abundant in the early postglacial vegetation and that tundra was present near the edge of the retreating ice sheet as far south as Massachusetts.
The disappearance or near-disappearance from New Brunswick of these formerly more widespread species is due mainly to post-glacial climatic warming and the resulting change in dominant vegetation from open tundra to closed forest. Conversely, the survival of some arctic species in a few scattered outposts suggests local growing conditions approximating those in the arctic. The microclimate of the Albert Mines gypsum cliffs, even though they are north-facing and cool, is clearly not arctic-like. However, the soft gypsum bedrock weathers and crumbles rapidly, and the cliffs and talus slopes here must have been shifting position continuously over the past several thousand years. This instability has prevented the establishment of trees and tall shrubs or herbaceous plants which might shade or otherwise out-compete the light-demanding arctic species.
Like tundra soils, the gypsum outcrop soils here remain thin and patchy, being continuously disturbed by natural erosion. In the surrounding forest the influence of gypsum on the vegetation is masked by the development of a thick layer of decaying plant litter. The fact that gypsum outcrop plants are found elsewhere mainly or only on limestone indicates that the soils formed on these two rock types share certain key characteristics. Gypsum is a rock-forming mineral consisting of calcium sulphate (Ca SO4) and water. Limestones vary greatly in purity but are composed largely of calcium carbonate (Ca CO3). Calcium carbonate in solution tends to neutralize soil acidity (which is why lime is spread on lawns and fields) but this is not the case with gypsum. Thus, the high concentrations of calcium, rather than the pH of the outcrop soils, may account for the overlap in gypsum and limestone floras. Whether the association of these plants with calcium-rich rocks reflects a requirement for or a tolerance of this particular chemistry is not fully understood.
In summary, then, several factors may have contributed to the survival and isolation of a group of rare arctic species at this locality: climatic warming, vegetation change, natural erosion, reduced competition and unusual soil chemistry.
There has been extensive quarrying in the past of the gypsum deposits near Albert Mines, but the cliff and talus site with rare arctic plants is still intact. This site was proposed as an ecological reserve in 1974. The New Brunswick Ecological Reserves Act came into effect in 1976 and provides for the establishment of reserves to preserve representative natural ecosystems as well as the habitats of rare or endangered species. The Albert Mines gypsum cliffs and their rare flora remain a priority for protection as an ecological reserve, but as of 1993, this site had not yet been formally designated.
Publicizing the locations of rare plants and animals with the aim of fostering concern for their welfare carries with it the risk that these species and their habitats will then be exposed to greater disturbance. The populations of arctic plants near Albert Mines could easily be destroyed by trampling or climbing on their gypsum cliff and talus habitat. Their numbers are also too small to sustain picking or transplanting to wildflower or rock gardens. Individuals and groups visiting the area should be fully aware of these concerns.
Cliffs, beaches, river shores, marshes, bogs, and other naturally open sites often have interesting and uncommon species. Becoming informed about the significance and sensitivity of such habitats is one of the first steps that can be taken by those who want to help preserve them. Several citizens' organizations, including the N.B. Federation of Naturalists, Nature Trust of N.B., and Conservation Council of N.B., provide opportunities for individuals to become knowledgeable about the diversity of species and ecosystems in the province and to work toward the protection of natural areas.
Given, D.R. & J.H. Soper. 1981. The arctic-alpine element of the vascular flora at Lake Superior. National Museums of Canada, Publications in Botany 10: 1-70.
Hinds, H.R. 1983. The rare vascular plants of New Brunswick. Syllogeus 50: 1-38 + maps.
Pielou, E.C. 1991. After the Ice Age: the return of life to glaciated North America. University of Chicago Press, Chicago. 366 pp.
Ritchie, J.C. 1987. Postglacial vegetation of Canada. Cambridge University Press, Cambridge. 178 pp.
Roberts, P.R. 1965. New records of arctic species in southeastern New Brunswick. Rhodora 67: 92-93.