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COSEWIC Assessment and Status Report on the Baikal Sedge in Canada

Habitat

Habitat Requirements

Carex sabulosa occurs only on semi-stabilized or active sand dunes. These dunes are usually 0.6 to 4 m deep. Although the ramets of these rhizomatous plants have the ability to send up new ramets when older ones have been completely buried, sand deposits greater than 1 m in depth, occurring over short periods, appear to restrict the growth of the ramets.

In the Kluane National Park Reserve, Carex sabulosa forms a plant community type that occurs only on the semi-stabilized sand dunes near the confluence of the Kaskawulsh and Dezadeash rivers (Figure 4, Douglas 1974). In 2003, almost all of the available dunes system was vegetated with the Carex sabulosa community type. This community type is a pioneer community on the dunes and appears to be relatively stable with only minimal invasion on the dune edges. It is a relatively young community since it is located on the site of Recent Lake Alsek. This proglacial lake, formed by the damming of the Alsek River by the Lowell Glacier, existed 150 years ago and had an upper shoreline at an elevation of about 604 to 640 m (Kindle 1952, Johnson and Raup 1964).

The Carex sabulosa community type at the Kaskawulsh and Dezadeash rivers has a low mean average cover of 15% and a frequency of 98% and is the only prominent species in this community type (Douglas 1974). Other constant species, with low prominence, include Elymus calderi (formerly known as Agropyron yukonensis), Equisetum pratense, and Artemisia alaskana. An average of five species per stand (total of 10) occur in this community. Juniperus communis, which was not encountered in any of the sampled stands, is a sporadic invader of the Carex sabulosa community. Only one other rare plant species, Corispermum ochotense var. alaskanumFootnote 4, occurs on the dunes. It occurs at only two other sites in the Yukon (Douglas et al. 2004).

At the Takhini River and the Bennett Lake dune systems the dunes are generally much more active than those at the Kaskawulsh and Dezadeash rivers. Sand accumulations, however, are not greater than the species can tolerate. About 75% of these dunes were vegetated in 2003. On these sparsely vegetated dunes, Carex sabulosa is always the most prominent species and may occur with a number of other species (Figures 5 and 6) or may be the sole species present (Figures 7 and 8). Other frequent, but sparse, dune species include Artemisia campestris, Aster sibiricus, Bromus pumpellianus, Calamagrostis purpurascens, Elymus calderi, Equisetum arvense, Festuca saximontana, Kobresia myosuroides, Lupinus kuschei, Oxytropis campestris, Pinus contorta, Populus balsamifera, Polemonium pulcherrimum, Silene acaulis and Solidago simplex.


Figure 5: The Semi-stabilized Dunes Near the Confluence of the Kaskawulsh and Dezadeash Rivers Occur on the Former Lakebed of Recent Lake Alsek

Figure 5: The semi-stabilized dunes near the confluence of the Kaskawulsh and Dezadeash Rivers occur on the former lakebed of Recent Lake Alsek.

The beach ridges of Recent Lake Alsek are evident on the lower mountain slopes (Photo by S.J. Smith, Douglas Ecological Consultants Ltd.).


Figure 6: The Well-vegetated Portion of the Dune System at Takhini River (South Dunes)

Figure 6: The well-vegetated portion of the dune system atTakhiniRiver(south dunes).

Carex sabulosa is the most abundant species in this view but many associates are also evident (Photo by S.J. Smith,Douglas Ecological Consultants Ltd.).


Figure 7: The Entrance to the Takhini River (North Dunes) System

Figure 7: The entrance to the Takhini River (north dunes) system.

Photo by S.J. Smith, Douglas Ecological Consultants Ltd.


Figure 8: Carex sabulosa Abundance on Parts of the Dune System at Bennett Lake, Near the Town of Carcross

Figure 8. Carex sabulosa abundance on parts of the dune system at BennettLake, near the town of Carcross.

It is essentially the only species on the active dunes (Photo by S.J. Smith, Douglas Ecological Consultants Ltd.).


Figure 9: Extent of Vegetational Cover of Dune System Near Carcross

Figure 9: Extent of vegetational cover of dune system near Carcross.

Almost 90% of this dune system along the Klondike Highway, near the town of Carcross, is unvegetated. This is due mainly to extremely high winds that move large amounts of sand that completely cover the vegetation (Photo by S.J. Smith, Douglas Ecological Consultants Ltd.).

The dune system along the Klondike Highway, near Carcross, included the most active dunes encountered. In fact, sand distribution and accumulations are so great that Carex sabulosa is unable to persist on about 90% of the dunes. Although there is evidence of invasion by Pinus contorta and Populus balsamifera, it is likely that sand movement eliminates about the same percentage of older trees. Most of the vegetation at the dunes consists solely of Carex sabulosa, but in some areas many of the species mentioned above may be found.

The habitat of the Christmas Bay, Kluane Lake, location remains unknown since collection label information is lacking and attempts to relocate the site in 2003 were unsuccessful. There were only several m² of dune blowouts and less than 200 m² of sandy beach at this location.


Trends

The sand dune habitat of Carex sabulosa has been substantially reduced since glaciation. The reductions are mostly due to invading vegetation through natural succession where dune formation is no longer able to continue. The dunes that remain appear to be maintained at present by a consistent source of materials and consistent winds.

Air photos taken during the mid-1940s and, more recently, between 1977 and 1999, indicate that all but one of the five extant dunes systems remain unchanged. Only the Bennett Lake dunes, near Carcross, show significant changes between 1948 and 1999. There appears to be a reduction of about 15 to 20% in dune area at this site.

Observations made by G.W. Douglas in 1974, 1978, 1992 and 2003 indicate that the large central area of the dunes along the Klondike Highway, near Carcross, has remained mostly unvegetated during recent years. It is likely that winds coming off Bennett Lake are much stronger than those encountered on the other dune systems in the southern Yukon.


Protection/Ownership

The largest population of Carex sabulosa in the Yukon occurs at the confluence of the Dezadeash and Kaskawulsh rivers in Kluane National Park Reserve. The dune systems along the Takhini River will be protected within the boundaries of the proposed Kusawa Territorial Park, the establishment of which was triggered by the signing of the Kwanlin Dun First Nation’s Final Agreement in February 2005. However, a management plan for this park will not be drawn up until the Carcross/Tagish First Nation ratifies their final agreement. The other extant dune systems at the Takhini River and Carcross occur on Crown land.

Footnotes

Footnote 4

This species was recorded by G.W. Douglas at the Kaskawulsh/Dezadeash rivers and at Christmas Bay, Kluane Lake during a 2003 survey. This plant had not been recorded south of the Dawson area previously.

Return to footnote 4 referrer