BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Eriophorum vaginatum | Sheathed Cottonsedge 



GENERAL BOTANICAL CHARACTERISTICS : 
Sheathed cottonsedge is a native, tussock-forming graminoid. Its culm
varies from 8 to 28 inches (20-70 cm) in length and is sheathed to half
its length.  The acaulescent leaves and scales are tightly compacted.
Sheathed cottonsedge foliage dies back each winter, but basal portions
of leaves and stems remain green [14].  The inflorescense is a densely
tufted cyme composed of multiflowered spikelets.  The fruit is an achene
[25,19].  Roots are densely fibrous and die back to rootstocks each
winter [36,35,39].  The roots hydrolyze and absorb organic phosphorus
compounds from the soil, providing up to 69 percent of the plant's
phosphorus requirement [31,39].  Sheathed cottonsedge does not form
mycorrhizal associations [6].

Sheathed cottonsedge tussocks are composed of 300 to 600 individual
tillers [14].  They are elevated above ground level.  Tussocks near
Toolik Lake, Alaska, averaged 8 inches (20 cm) in diameter.  Measuring
from tiller bases, they also averaged 8 inches above ground.  Roots
averaged 12 inches (30 cm) in length, extending 4 inches (10 cm) below
ground until reaching the permafrost layer [39].  Individual tillers
live less than 8 years; estimated age of mature tussocks ranges from 122
to 187 years [36].


RAUNKIAER LIFE FORM : 
   Chamaephyte


REGENERATION PROCESSES : 
Sheathed cottonsedge reproduces sexually by seed and vegetatively by
tillering [2,18].  Seeds are first produced at age 3 and are dispersed
by wind [56].  Flower and seed production increase with disturbance [5].
Sheathed cottonsedge often dominates northern seedbanks:  97 percent of
seed found at a site on Kuparuk Ridge of the Brooks Range was sheathed
cottonsedge and Bigelow sedge [17].  Peat-buried sheathed cottonsedge
seeds remain viable for long periods of time in cold arctic
environments.  Longevity of seed collected from peatbeds near Eagle
Creek, Alaska, was estimated to be at least 200 years [38].  Sheathed
cottonsedge seeds readily germinate after overwintering when exposed to
light and warm temperatures [18].  Live mosses or liverworts, dead
leaves, and dead peat are favorable seedbeds.  Seedling establishment is
best on disturbed sites; it is rare in mature tussock communities [37].
Seedling growth rate is largely controlled by nutrient availability and
is most rapid after fire has released nutrients into the soil [7].
Tallis [53] found that tussocks increase in number during dry years,
probably because of drought intolerance of Bigelow sedge seedlings.

Sheathed cottonsedge produces tillers at the rate of one to three per
year, with tillering increasing in response to disturbance.  Tillers die
after flowering but decompose slowly due to compaction and low
temperature [14,15].


SITE CHARACTERISTICS : 
Sheathed cottonsedge occurs in a continental climate with extreme
seasonal variations in temperature [4].  It grows on plateaus and gently
sloping foothills of interior Alaska and alpine areas of the notheastern
United States [30].  It is found in tundra bogs, muskegs, and pockets of
boreal forest [36,62].  In the Adirondack Mountains, it occurs at
elevations of 500 to 1,500 feet (1,600-5,000 m) [33].  In Alaska, it
occurs at 3,600 to 9,800 feet (1,100-3,000 m) [9].

Parent materials of sheathed cottonsedge-supporting soils include
polymictic conglomerate, lithic wacke, siltstone, and shale overlain by
frozen glacial till and sand or sandy loam.  Depth of thaw into mineral
soil is 2 to 4 inches (5-10 cm).  Soils belong to the Inceptisol order.
Mineral soil is usually covered by an up to 16-inch-thick (40 cm)
horizon of poorly decomposed peat [2,17,26,59].  The superficial surface
layer may be a hepatic, moss, or lichen mat [17].  Soils are well to
poorly drained, low in nutrients, and acidic [2,39,56].  Soil pH ranges
from 3.0 to 5.1 in Yukon Territory and the Northwest Territories [50].


SUCCESSIONAL STATUS : 
Obligate Initial Community Speices

Sheathed cottonsedge colonizes disturbed sites including burns, frost
boils, and gravel pits [8,24,27,56].  It increased in importance
wherever disturbance occurred in Yukon Territory [63].  Sheathed
cottonsedge tussock communities are stable for many decades, but are
eventually replaced in the absence of disturbance.  Sheathed cottonsedge
is replaced by Carex species near Fairbanks, Alaska, and by Scotch
heather on the Seward Peninsula [4,26].  It is sometimes replaced by
black spruce below the northern tree limit [29].  In the Lake States, it
is replaced by tamarack (Larix laricina) and red pine (Pinus resinosa)
[60].


SEASONAL DEVELOPMENT : 
Sheathed cottonsedge flower buds are formed the year prior to flowering
[8].  Sheathed cottonsedge begins growth earlier in spring than most
tundra plant species [35].  Early growth is rapid, with new root tissue
initiated first.  Kummero and others [34] reported that new root growth
began prior to snowmelt (early June) in the northern foothills of the
Brooks Range.  Sheathed cottonsedge phenological development near
Fairbanks, Alaska, was reported as follows [41]:

new leaves initiated:  June to early July
flowers:  June to mid-July
fruits:  July
seeds dispersed:  late July to mid-August
senescence:  late July to August

Sheathed cottonsedge in the Adirondack Mountains fruits from June 9 to
July 6, and seed is disseminated before late September [33].

Related categories for Species: Eriophorum vaginatum | Sheathed Cottonsedge