Canadian Athabasca Non-Coastal Sand Dunes

In northwestern Saskatchewan and adjacent parts of Alberta there is an active dune system known as Athabasca Dunes with species derived from Arctic, Boreal and Great Plains elements. A number of these are endemic and yet this part of Canada is not noted for endemism. This small pocket of endemics in a region otherwise devoid of them is of considerable evolutionary interest. Endemism in the Lake Michigan and Kobuk River dunes is far less pronounced. At the latter there is just one endemic species, Oxytropis kobukensis (Fabaceae) and an ecotype of Astragalus alpinus, while at Lake Michigan dunes the only endemic is Salix syrticola (Salicaceae). In the areas of active sand at Athabasca there is a sparse distribution of sand trapping species forming hillocks and cushions. These are mainly grasses such as Bromus pumpellianus, Calamagrostis stricta, Elymus mollis, Festuca rubra subsp. richardsonii and the endemic Deschampsia mackenzieana (Poaceae). Scattered among the grass, other species such as Artemisia borealis, Stellaria longipes and the endemic Achillea lanulosa susp. megacephala (Asteraceae), Stellaria arenicola (Caryophyllaceae) and Tanecetum huronense var. floccosum (Asteraceae) may be present. The vegetation of rolling dunes also include the above mentioned species together with the endemic willow shrubs Salix brachycarpa var. psammophila, S. silicicola, and S. turnorii (Salicaceae). The latter, with its requirement for permanent ground water, is also an important feature of Athabasca’s dune slacks where seasonal flooding occurs and the water table is generally close to the surface. Here graminoids such as Juncus arcticus and the endemic Deschampsia mackenzieana (Poaceae) are also important. Other species include Carex abdita, Juncus alpinus and the endemic Stellaria arenicola (Caryophyllaceae). In wet depressions, mosses may also be present together with the rare endemic Silene acaulis f. athabascensis (Caryophyllaceae). On areas of stabilized sand, trees such as Larix laricina, Picea mariana and Pinus banksiana (jack pine) can become established, but the most common forest type in the area is open jack pine - lichen forests. In places the ground layer of these can be almost exclusively dominated by fruticose lichens such as Cladina arbuscula, C. mitis, C. rangiferina, C. stellaris, Cladonia amaurocraea and C. gracilis and jack pine may be the only vascular plant.  But in general other species are present such as xerophytic mosses, various herbs and trailing shrubs. In fact, the initial appearance of meagerness is deceptive and overall many vascular plants can be found. Amongst these are Apocynum androsaemifolia, Aralia nudicaulis, Comandra umbellata, Dicanthelium acuminatum, Geocaulon lividum, Hudsonia tomentosa, Ledum groenlandicum, Oryzopsis pungens and the endemic Lechea intermedia var. depauperata (Cistaceae) to name but a few.

References

Jonker, P. M. & Rowe, J. S. 2001. The Sand Dunes of Lake Athabasca. University Extension Press. University of Saskatchewan.

Raup, H. M. & Argus, G. W. 1982. The Lake Athabasca sand dunes of Northern Saskatchewan and Alberta, Canada. National Museums of Canada. Publications in Botany, No. 12.