BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Carex aquatilis | Water Sedge 



GENERAL BOTANICAL CHARACTERISTICS : 
Water sedge is a native, water-obligate, long-lived perennial [8].  It
varies in height from 0.6 to 1.7 feet (20-140 cm) [58].  In arctic and
alpine populations, water sedge exhibits smaller tiller size and slower
leaf production [14].  The aerial stem and leaves are slender, flat, and
elongate.  The stems are smooth and rounded, and the glaucous-tipped
leaves are as long as or a little shorter than the culm.  Individual
shoots of water sedge live approximately 5 years, producing two to three
leaves per year.  The roots live two to three times longer than the
shoots [6].  In arctic systems, the roots are generally confined to the
top 8 to 12 inches (20-30 cm) of soil [19].  The rhizomes are coarse,
scaly, brown, and cordlike [34].  The rhizomes of water sedge grow
approximately 2.1 inches (5.3 cm) below the soil surface and form dense
clumps [20,3].  The dense rhizome network results in a tiller density of
11,000 to 22,000 shoots per square foot (1,000-2,000 shoots/m sq) [6,8].
This dense sod stabilizes soils and streambanks.  Water sedge in the
form of floating mats at lake and pond shores has been reported, but
this is not very common.


RAUNKIAER LIFE FORM : 
   Hemicryptophyte
   Cryptophyte


REGENERATION PROCESSES : 
Water sedge regenerates primarily through the spreading of underground
rhizomes [5,54].  Long and short rhizomes take part in vegetative
reproduction.  The long rhizomes branch to produce another plant.  The
short rhizomes produce more water sedge in tufts or "tiller clumps" [3].

Each year approximately 6 to 9 percent of the shoots flower, and few
viable seeds are produced [6].  Pollination occurs by wind.  Seed
germination rates vary between 20 and 60 percent [35].  Seedlings are
most common on drier sites, especially for C. aquatilis var. stans, and
on burned sites [7].
 
Sexual and vegetative reproduction rates are slow, resulting in limited
colonization.  A low rate of colonization has been found to correlate
with soil temperature and level of phosphorous in the soil [1].


SITE CHARACTERISTICS : 
Water sedge is found in areas of shallow water or immediately adjacent
to water [8].  These include swamps, wet meadows, pond or lake shores,
streams, old riverbanks, floodplains, fens or marshes, sedge meadow
tundra, silted-in beaver ponds, or any other low-lying area with
restricted water drainage [31,10,21,37].  It has also been found near
hot springs in Alaska [14].

The water regime best suited for water sedge is one with the water table
above ground level in early June and adequate moisture in the root zone
throughout the year [20,21].  Water sedge grows best on flat or concave
surfaces with a maximum slope of 10 percent [52].  Water sedge
habitats include mountainous regions, meadows, riparian zones, marshes, subarctic zones, and arctic tundra
[56,63,64].  The elevational range of water sedge is quite variable.
Following is a listing of the elevational ranges in various states
[8,14,24,30,42]:

    State               elevation (ft)           elevation (m)

Alaska                    14 to 13,500               5 to   500
California             5,000 to 10,500           1,852 to 3,889
Colorado               8,000 to 12,000           2,963 to 4,629
Montana                2,300 to  6,000             701 to 1,829
Utah                   8,000 to 11,000           2,963 to 4,074
Idaho (southeast)      8,000 to 11,000           2,963 to 4,074

Water sedge usually grows in soils belonging to one of three taxonomic
soil orders:  Histosol, Inceptisol (cryaquepts), or Mollisol (cruaquoll)
[39,59].  It grows best in cold soils with textures ranging from sandy
loam to clay [14,30].  The soil climate can vary from semiarid to humid
[21,59].  The soil reactions are slightly acidic, with a soil pH range
of 6.2 to 7.1 [8].  The organic matter is mainly composed of massive
roots and rhizomes, varying in degree of decomposition [6,52].  Water
sedge will also grow on mineral soils.  The soil characteristically has
a very high moisture-holding capacity with shallow to deep peat and a
shallow to moderate active layer [19,20].  It appears that phosphorous
is the limiting element of water sedge in wet tundra and meadows and
correlates with soil temperature in tiller height and number of leaves
[14].


SUCCESSIONAL STATUS : 
Water sedge is an opportunistic colonizer of suitable environments and
exposed mineral substrates [8,52].  It exists in seral and climax
communities in the arctic but is mainly reported in seral communities
[5].  Disturbed areas are colonized by seedling establishment on drier
sites and by vegetative expansion on wetter sites [47].  Water sedge is
long-lived and tends to replace shorter lived species such as cibola
milkvetch (Astragalus alpinus) and Mackenzie sweetvetch (Hedysarum
mackenzii) [12].  In immature fens, water sedge is a dominant species.
After water sedge establishment, further succession incorporates willow
and other shrubs into the community [21].  The water regime appears to
control succession in the Peace-Athabasca River delta.  Water sedge is a
strong competitor [19].  The rhizomes slowly invade bare, moist soils;
the formation of dense clumps makes it difficult for other species to
establish [6,8].  At disturbed sites, sedges initially are dominant, but
colonization is slow in arctic habitats due to low sexual reproduction
and tillering rates [6,12].


SEASONAL DEVELOPMENT : 
During the winter, 10 percent of green tissue survives, which gives
water sedge an early growing advantage in the spring.  Shoot growth is
completed in 30 to 35 days of the 50 to 55 day growing season in arctic
habitats [6].  Another source reported a leaf growing period of 35 to 40
days [19].  From May to late July, new leaf growth is plentiful.  Water
sedge normally flowers between May and June.  At higher elevations, it
may flower as late as August [58].

Related categories for Species: Carex aquatilis | Water Sedge