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COSEWIC assessment and update status report on the Athabasca Thrift, ssp. interior in Canada

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COSEWIC
Executive Summary

Athbasca Thrift
Armeria Maritima Ssp. Interior

Species Information

Athabasca thrift is a perennial herb with a taproot and a branched woody base from which arise one to several rosettes of flat linear leaves. An erect flowering stem, to 25 cm in height, develops from the centre of each rosette. The small pink flowers are borne in a dense, nearly spherical head. The flowers are subtended by two sets of scarious bracts; the calyx tube is hairless and distinctly lobed.

 

Distribution

This subspecies of a wide-ranging species is known only from the south shore of Lake Athabasca, Saskatchewan, where it occurs in the three large dune fields: (1) the William River Dunes located between Ennuyeuse Cr. and the William River, (2) the Thomson Bay Dunes located between William River and Cantara Lake, and (3) the MacFarlane River Dunes, located just west of the MacFarlane River and in the smaller dunes at Archibald Lake.

 

Habitat

Athabasca thrift is restricted to dune slacks and gravel barrens.

 

Biology

Little is known about the specific biology of this subspecies. Seedlings become established both on gravel pavements and on moist to wet dune slacks. Plants growing in dune slacks are young, vigorous plants that eventually become covered by the shifting sand. Old plants are found only on the relatively stable gravel pavements.

 

Population Sizes and Trends

The population of this subspecies is very small, but its exact size and trends cannot be estimated without quantitative data. This subspecies occurs only as small populations or as occasional individuals. Its main habitats, which are gravel pavements, are themselves relatively uncommon and the vegetation on them is very sparse. Species growing on these gravel pavements, therefore, are among the least common species in the Athabasca sand dunes. This subspecies is thought to be one of the most uncommon of the endemics in the sand dunes. There are only eighteen herbarium collections of this taxon.

 

Limiting Factors and Threats

All-terrain vehicle use for recreational activities has been identified as a threat to the sand dunes and their endemics. Other potential threats may arise from future pressures for mining exploration. Increased visitor use may pose some threats, although such recreational activities, especially from canoeists may be restricted to areas of water access.

 

Special Significance of the Species

The subspecies is mainly notable for its restricted range as a Canadian endemic.

 

Existing Protection or Other Status Designations

The main protection of this subspecies comes from its occurrence in the Athabasca Sand Dunes Wilderness Provincial Park.

 

Summary of Status Report

Athabasca thrift is one of ten endemic vascular plants known from the Lake Athabasca sand dune region of northwestern Saskatchewan. It is one of the most uncommon endemics in the Athabasca sand dunes. Its habitat is localized and fragile. Although the Athabasca sand dunes enjoy Provincial Wilderness Park protection there is reason to believe that pressures from mining and tourism will require continued vigilance.