This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available: [4,62,63,64,80,95,96,101,107,156].
Water sedge is a native [95,96], water-obligate [35,87,88,120], long-lived perennial [86,186,192,203]. The lifespan of water sedge is from 4 to 10 years [27,186,203]. However, the roots and rhizomes of water sedge generally do not die until 1 to 4 years after aboveground dieback [186,203].
The culms of water sedge are slender, sharply triangular, 6 to 60 inches (15-150 cm) tall [4,96,156,214] and borne singly or few together on rhizomes [96,105,128,156,214]. The culms of C. a. var. aquatilis average 20 to 41 inches (50-105 cm) tall [82]. At the southern end of Lake St. Francis, Quebec, water sedge culm density averaged 505/m² [15]. Water sedge plants collected from Idaho State lands had a mean height of 22 inches (55 cm), with a minimum and maximum height of 14 inches (35 cm) and 27 inches (68 cm), respectively [116]. The leaves of water sedge are flat, elongate, 2 to 7 mm wide, and occur on the lower half of the culms [214]. Water sedge plants produce 4 to 5 new leaves a year [186]. In the High Arctic, the leaves of water sedge are mature in terms of photosynthetic rate for approximately 27 days [31]. The inflorescence of water sedge has 3 to 10 cylindrical spikelets [96,128,192], not closely crowded [96], and is 0.6 to 2 inches (1.5-5 cm) long [96]. The fruits of water sedge are lens-shaped achenes 1 to 2 mm wide [120,121,128,192].
Water sedge is a sod-forming [96], clonal plant [5,68], with an extensive network of vertical and horizontal long, stout rhizomes interspersed with expansive meshes of fine roots [4,95,96,165,214]. Water sedge plants are capable of extensive belowground production in low oxygen and anoxic environments by forming well-developed aerenchyma [68]. The rhizomes of C. a. var. stans were excavated within a polar oasis at Sverdrup Pass, Ellesmere Island, Northwest Territories. The number of branchings per rhizome node (n±s) was 1.48±0.59. The internodal rhizome length (inches±s) was 3.46±1.51 (8.80 cm±3.83). The number of nodes per individual rhizome (n±s) was 2.0±1.18. The average rhizome depth (inches±s) for C. a. var. stans was 2.1±3.2 (5.33 cm±8.1) [59].
Rhizome growth patterns for water sedge are complex. Water sedge rhizomes can be divided into 2 classes. "Spreading rhizomes" are 6 to 8 inches (15-20 cm) long and produce almost all of the roots. "Clumping rhizomes" are daughters of the spreading rhizomes and rarely produce roots or daughter rhizomes. Clumping rhizomes are very short (0 to 0.4 inch (0-1 cm)) and are bunched tightly around the "mother" spreading rhizome [186].
At the peak of the growing season (1 August) on wet tundra near Barrow, Alaska, the root system of water sedge ranged from 0.8 to 10 inches (2-25 cm) below the soil surface with the greatest concentration of roots from 4 to 8 inches (10-20 cm) [186].
Fire adaptations: Water sedge establishes after fire through seed and/or lateral spread by rhizomes [119,120,121,170].
FIRE REGIMES: At the time of this review (2006), there is very little information on the fire ecology of water sedge and its varieties. While water sedge is found throughout the United States (excluding the Southeast) and Canada (See General Distribution), the vast majority of literature addresses water sedge in Arctic communities, with little discussion on fire ecology. In addition, water sedge occurs in wetlands where the fire regime may be decidedly different than the larger surrounding communities. The information presented below describes the fire regime of water sedge in several communities where a fire record is found in the literature.
Arctic tundra: Fires are common in the polar desert biome and Arctic tundra. Most fires are relatively small, burning from 2.5 to 25 acres (1-10 ha), but some have covered 25 to 1000 km² [31].
Water sedge is one the most important plant species in the Seward Peninsula tundra ecosystem of Alaska. The first recorded fire on the Seward Peninsula occurred in 1900, but likely fires caused by lightning and Native Alaskans occurred frequently prior to 1900. A United States Geologic Service journal entry from 1906 described summer tundra fires as "common." There is a gap in the tundra fire record from 1910 to 1956, though fires started by miners clearing the land and Native Alaskans trying to reduce the mosquito population are likely. From 1968 to 1973 the Bureau of Land Management recorded 21 fires on the Seward Peninsula, with fire peaks in 1971 and 1972. During this 6-year period (1968-1973) most of the tundra fires burned in the east, central, and southern portions of the Seward Peninsula. During the summer of 1977, a number of lightning-caused fires burned 887,000 acres (359,000 ha) of tundra in the northern and western sections of the Seward Peninsula [169].
Boreal forests: Forest fires in the taiga of northwestern Manitoba and Saskatchewan and southern Northwest Territories occur frequently [150,182]. During 1956 to 1972, 41 fires burned an area of 1,422,550 acres (575,687 ha) in Saskatchewan, and 47 fires burned an area of 2,428,310 acres (982,701 ha) in Manitoba from 1955 to 1967. Of those fires, 75% in Saskatchewan and 66% in Manitoba occurred on upland sites outside of water sedge's range [151].
Deciduous and mixed forests: Water sedge is a dominant species in wet meadows of the Gunnison National Forest, Colorado. Overstory species surrounding water sedge marshes include pure and mixed stands of Rocky Mountain lodgepole pine, quaking aspen, Engelmann spruce, and subalpine fir. A fire has not been recorded there since the establishment of the National Forest in 1905 [72].
The following table provides fire return intervals for plant communities and ecosystems, and adjacent communities, where water sedge is important. Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Community or ecosystem Dominant species Fire return interval range (years) silver fir-Douglas-fir Abies amabilis-Pseudotsuga menziesii var. menziesii >200 grand fir Abies grandis 35-200 [9] maple-beech Acer-Fagus spp. 684-1,385 [47,212] birch Betula spp. 80-230 [196] cheatgrass Bromus tectorum 162,215] beech-sugar maple Fagus spp.-Acer saccharum >1,000 [212] tamarack Larix laricina 35-200 [160] western larch Larix occidentalis 25-350 [10,22,60] Great Lakes spruce-fir Picea-Abies spp. 35 to >200 northeastern spruce-fir Picea-Abies spp. 35-200 [66] Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to >200 [9] black spruce Picea mariana 35-200 [66] blue spruce* Picea pungens 35-200 [9] red spruce* Picea rubens 35-200 [66] whitebark pine* Pinus albicaulis 50-200 [2,7] Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [21,22,198] Sierra lodgepole pine* Pinus contorta var. murrayana 35-200 western white pine* Pinus monticola 50-200 Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [9] interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [9,17,133] eastern white pine Pinus strobus 35-200 [196,212] eastern white pine-eastern hemlock Pinus strobus-Tsuga canadensis 35-200 eastern white pine-northern red oak-red maple Pinus strobus-Quercus rubra-Acer rubrum 35-200 [212] eastern cottonwood Populus deltoides <35 to 200 [160] quaking aspen-paper birch Populus tremuloides-Betula papyrifera 35-200 [66,212] quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [9,83,149] black cherry-sugar maple Prunus serotina-Acer saccharum >1,000 [212] mountain grasslands Pseudoroegneria spicata 3-40 (µ=10) [8,9] Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [9,10,11] coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [9,154,178] California mixed evergreen Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii <35 [9] western redcedar-western hemlock Thuja plicata-Tsuga heterophylla >200 western hemlock-Sitka spruce Tsuga heterophylla-Picea sitchensis >200 mountain hemlock* Tsuga mertensiana 35 to >200 [9] *fire return interval varies widely; trends in variation are noted in the species reviewThe limited research available on the response of water sedge suggests that fire may increase coverage, particularly in areas where it is dominant. If fire is used to manage water sedge, however, managers should use caution and follow the guidelines addressed below.
Burning season: Since water sedge occurs in wetlands, it usually cannot be burned until late summer or fall when vegetation is sufficiently dry [86,119].
Erosion control: Water sedge provides excellent erosion protection along streambanks [86] and buffers water forces and filters sediments during spring runoff [119]. Therefore, managers burning along water sedge dominated streambanks and runoff areas should exercise caution.
Plant communities: On wetter sites in the Rocky Mountain lodgepole pine (Pinus contorta var. latifolia)/water sedge association, overstory removal may cause an elevation in the water table and a temporary conversion to a willow (Salix spp.)/water sedge association [119].
Soil: During the summer of 1977, a number of lightning-caused fires burned 887,000 acres (359,000 ha) of tundra in the northern and western sections of the Seward Peninsula. On study site 8, which is dominated by water sedge and white cottongrass, the fire caused an increase in the tundra thaw depth during postfire year 1 and 2. The following table describes the prefire (1973) and postfire year 1 (1978) and 2 (1979) tundra thaw depth and increase in thaw depth between years [170]:
Thaw depth (cm±s)Increase in thaw depth (cm (%))
1973 (prefire) 1978 (postfire year 1) 1979 (postfire year 2) 1978-79 1973-79 23.5±2.9 31.1±2.9 42.6±1.9 +11.5 (37%) +19.1 (81%)Water sedge is found in swamps [96,181], bogs [127,155,165,181], marshes [95,96,116,152,155], very wet soil [95,96,156], ponds [20,96,112,214], lakes [96,124,214], fens [165], marshy meadows [80,127,130,139,156,214], lagoons [1], streams [20,116,214], periglacial features [26], permafrost marshes and pond margins [44,98,112], and peatlands [52,136].
All water sedge communities are found in mountainous regions or in subarctic and arctic tundra habitats [174]. Water sedge is widespread and important in boreal and arctic wetland vegetation [157]. In Montana, >99% of all sites with water sedge were wetlands [35,87,88].
Climate: Water sedge can survive the harsh elements of the Arctic [5,6] where the mean annual temperature is as low as Â4 °F (Â20 °C) [173]. Water sedge communities thrive where annual precipitation is as low as 1.4 inches (35 mm) [173] and as high as 40 inches (1010 mm) or more [127]. Water sedge is an important species on the Arctic tundra and in the polar desert biome, where the length of the growing season varies from 1.5 to 4 months [31].
Elevation: The elevational ranges for water sedge are presented in the table below:
State/Province Elevation Alaska sea level to 1,800 feet [29,98,172] Arizona 1,325 to 3,100 feet [193] California 5,000 to 11,120 feet [99,156] Colorado 5,000 to 12,500 feet [20,53,90,127] Montana 2,550 to 6,900 feet [81,135] New Mexico 6,000 to 11,000 feet [143,152] Nevada 6,000 to 11,000 feet [107,140] Utah 4,500 to 11,400 feet [189,214] Washington 500 to 5,210 feet [84,120] Wyoming 5,000 to +10,000 feet [54] Alberta 2,180 to 2,500 feet [136] British Columbia 5,250 to 9,150 feet [184] Northwest Territories sea level to 1,970 [100] Yukon Territory 330 to 6,270 feet [97]Environmental factors: Carex aquatilis var. aquatilis was studied at 5 locations in Alaska (arctic, muskeg, hot springs, and subalpine) and Colorado (alpine) to assess the effect air and soil temperature and available soil phosphorus have on growth rate. When all sites were considered, C. a. var. aquatilis aerial culm height showed a positive correlation with soil temperature (r²=0.50), air temperature (r²=0.37), and available soil phosphorus (r²=0.45). Carex aquatilis var. aquatilis aerial culms were smallest and leaf production slowest among arctic and alpine populations, where air and soil temperature and available soil phosphorus were lowest [44].
Litter: Thormann and others [199] studied the decomposition rate of water sedge leaves and rhizomes in the peatlands of boreal Alberta. Two years after water sedge plants cease growing, 75% of rhizomes and 54% of leaves completely decompose. During the 2 year decomposition study, water sedge leaves and rhizomes added 290 g/m² of carbon to the peat soil. Arp and others [13] discuss the effect of acid rock mining drainage on water sedge litter in Summit County, Colorado.
Soils: Soil orders on which water sedge commonly grow include Histosols, Inceptisols (cyraquepts), and/or Mollisols (cruaquolls) [118,207]. Water sedge grows best in cold, moist soils with textures ranging from sandy loam to clay [44,86,161]. It is often associated with soils high in organic matter [14]. At the southern end of Lake St. Francis, Quebec, water sedge grows on soils with an organic content of 79.3% [15]. Where water sedge grows on peatlands, the soil nitrogen level generally ranges from 1.43% to 2.27%, with an average value of 1.77% [89]. Water sedge is evenly distributed on peatland soils with a pH ranging from 3.0 to 7.9 at Candle Lake in central Saskatchewan [103]. Water sedge grows on peat soils 13 to 15 feet (4-4.6 m) deep in a central Alberta muskeg [136].
In 4 water sedge dominated fens in Summit County, Colorado, soil temperature ranges from 46.8 °F to 52.7 °F (8.8-11.2 °C), water pH ranges from 3.8 to 6.7, and the water table depth ranges from +2.2 to Â1.4 inches (+5.5 to Â5.1 cm) [13].
The soil constituents of 4 peat bogs where water sedge is dominant in central Alberta are detailed in a review by Lewis and Dowding [136].
Water table characteristics: Water sedge readily establishes in submerged areas [1]. It can withstand periods of 1 to 2 months of submersion [161]. At Candle Lake in central Saskatchewan, water sedge is evenly distributed on sites where the water table is from 30 inches (80 cm) below to 15 inches (39 cm) above ground surface. Some smaller populations occur where the water table ranges from 16 to 30 inches (40-80 cm) above ground surface [103]. In Yellowstone National Park, Wyoming, water sedge is dominant on sites where the water table is from ground surface to 70 cm below soil surface [38].
The livestock forage value for water sedge is variable, depending upon the time of year, previous grazing use, and the extent to which it is present [85]. Water sedge is found in moist environments, allowing it to stay green late into the growing season and provide forage when other species have gone dormant [25]. Given that water sedge is found in wet places, it is generally not grazed until late summer and fall when soils have dried [86]. Lewis [137] notes that cattle and horses in Utah heavily graze water sedge on overgrazed rangelands.
Ungulates: The forage value of water sedge for ungulates varies widely. Sedge meadows (water sedge and wheat sedge) are important grazing ground for wood bison in the Mackenzie Bison Sanctuary, Northwest Territories. During June of 1986, water and wheat sedge composed over 80% of wood bison's diet. By late summer and early fall, wood bison grazed the sedges substantially less than in early summer [129]. Water sedge is an important forage species for caribou on Alaska's arctic slope [216]. In northwestern Alaska, Klein [117] observed caribou actively selecting water sedge as winter forage. Water sedge is the most important winter forage species for muskox on Victoria Island in the Canadian High Arctic. Water sedge composes from 46.2% to 47.4% of their diet during early winter, and from 38.2% to 47.9% during late winter [183]. Water sedge is a valuable forage species for Alaskan reindeer during the summer [197]. Trudell and White [204] observed reindeer of Prudhoe Bay, Alaska, eating water sedge during the peak growing season (late July to mid-August). The eating rate (g/minute±s x) and biomass eaten (g/m²±s x) of water sedge by reindeer was 2.4±1.3 and 25.9±3.2, respectively. Sedge meadows, including those dominated by C. a. var. stans in the High Arctic of the Northwest Territories, provide the main grazing grounds for muskox and caribou [59,92]. On the Canadian Arctic Archipelago, water sedge is a substantial constituent of Peary caribou and muskox diets [130].
Water sedge is an abundant species in sedge meadows on southern Vancouver Island, British Columbia. During March through May the Columbian black-tailed deer feeds on water sedge, but it is not an integral part of its diet [56]. The diet of free-ranging wood bison of the Slave River lowlands, Northwest Territories, is composed of less than 10% water sedge [177]. The average standing biomass (kg/ha±s x) of water sedge on the Slave River lowlands of the Northwest Territories is 190±70 in wet habitats [177]. LeResche and Davis [134] observed over 28,000 bites taken by moose on Kenai Peninsula, Alaska in the summer of 1971. Of those bites observed, approximately 4% were taken from water sedge plants [134].
In Montana and Washington riparian and wetland sites, water sedge provides fair food for elk, mule deer, and whitetail deer, but poor food for pronghorn [35,87,88,120].
Waterfowl: Water sedge is an important source of food for a variety of large waterfowl. In northern Alaska along the Colville River delta, water sedge is heavily grazed by greater white-fronted geese, tundra swans, and black brant during late summer [23]. Aerial culms of water sedge provide autumn forage for lesser snow geese in the Arctic National Wildlife Refuge, Alaska [37]. Water sedge is a dominant species along the edges of Teshekpuk Lake within the National Petroleum Reserve Alaska. The area supports large populations of Canada geese, black brant, white-fronted geese, and snow geese that depend upon water sedge as a food source [61]. After snowmelt in spring and in areas with shallow standing water, lesser snow geese at Eskimo Point, Northwest Territories, pull shoots of C. a. var. stans and C. a. var. aquatilis from the ground [112]. Monda and others [153] observed tundra swan in the Arctic National Wildlife Refuge, Alaska, actively eating water sedge plants from 20 May to 15 September in 1988 and 1990.
Water sedge is grazed by lesser snow geese at La Perouse Bay, Manitoba. While the leaf tips are very high in nitrogen, it is not preferentially grazed because of its tough, tall leaves [75]. Lesser snow geese goslings from La Perouse Bay, fed water sedge in a controlled trial, lost weight when compared to goslings feeding exclusively on commercial feed [76].
At Bylot Island, Northwest Territories, water sedge is an important food for lesser snow geese [142]. The basal stems of water sedge constituted from 0.7% to 71.0% of the esophageal contents of lesser snow geese during 1989 to 1990. The leaves and rhizomes are also fed on by lesser snow geese, making up from 0.1% to 33% of their diets. The lesser snow geese were either prelaying, laying, and/or incubating during the study [78]. In the years 1983 and 1988, Hughes and others [100] observed greater snow geese goslings feeding on basal stems of C. a. var. stans on Bylot Island.
Rodents/small mammals: In Montana and Washington riparian and wetland sites, water sedge provides fair food for small mammals [35,87,88,120]. Sedge meadows, including those dominated by C. a. var. stans in the High Arctic of the Northwest Territories, provide the main grazing grounds for collared lemmings and arctic hares [59,92].
Palatability/nutritional value: Water sedge is moderately palatable [116,137]. Water sedge palatability in Montana and Washington riparian and wetland sites is listed as good for cattle, domestic sheep, and horses [35,87,88,120]. Water sedge has fair energy and nutritional value [35,87,88,120].
The mean nutrient content of water sedge at the southern end of Lake St. Francis, Quebec, is presented in the table below. The nutrient content provided is averaged across the growing season. Water sedge had the lowest nutrient content of the sedges (wooly sedge, lesser panicled sedge, tussock sedge, and hairy sedge (Carex lacustris)) studied at Lake St. Francis [15].
Mean tissue nutrient concentration (mg/g)
Ash Ca P N K Na Mg Cu Fe Mn Zn 47.38 4.565 1.256 11.53 13.72 0.618 1.385 0.007 0.095 0.099 0.058The mean nutritional content of water sedge at Pole Mountain, Wyoming, during early August 1944 to 1947 is presented in the table below. For further water sedge nutritional data during the growing seasons 1944 to 1947 at Pole Mountain see the review by Beath and Hamilton [25].
Year Ca (%) P (%) Moisture (%) Ash (%) Protein (%) Ether (%) Fiber (%) Carotene (mcg/g) 1944 0.55 0.22 5.65 7.71 12.32 3.27 29.48 169 1945 0.34 0.28 7.55 7.76 13.11 3.10 30.74 145 1946 0.46 0.39 6.88 7.26 14.39 4.83 25.86 308 1947 0.44 0.40 6.0 6.77 3.68 34.88 9.59 195On Banks Island, the westernmost island of the Canadian Arctic Archipelago, water sedge crude protein, digestibility, lignin, fiber, and energy content increase from the beginning of the growing season (mid-June) until the peak of the growing season (mid- to late July) and then begin to decline thereafter. During the summers 1993 to 1998, crude protein of water sedge ranged from 5% to 20%, mean percent digestibility ranged from approximately 15% to 37%, mean lignin content ranged from approximately 2% to 3%, mean percent fiber content ranged from approximately 30% to 40%, and energy content ranged from approximately 18 kJ/g to 20 kJ/g. The nutritional value of water sedge was highest in this study in the years when available moisture was greatest [131,132].
The nutritional value of water sedge (whole plants collected May 1971) at Kenai Peninsula, Alaska, is presented in the table below [134]:
P (%) Ca (%) K (%) Mg (%) Na (%) Protein (%) Ether (%) Fiber (%) Ash (%) Carbohydrates (%) 0.10 0.15 0.92 0.10 0.010 5.4 2.2 31.6 3.6 53.0Cover value: Water sedge is an excellent source of cover in riparian and wetland communities for birds and small mammals.
Water sedge provides cover for birds and small mammals at Wet Creek and Summit Creek, Idaho [46,146,147,148]. On Bylot Island, Northwest Territories, C. a. var. stans provides cover for greater snow geese from predators such as arctic fox, glaucous gull, long-tailed jaeger, parasitic jaeger, and common raven [100]. Water sedge stands in the Arctic National Wildlife Refuge, Alaska, provide prime habitat for nesting tundra swans [153]. Water sedge-common cattail (Typha latifolia) stands in the Wood Buffalo National Park, Canada, provide critical nesting habitat for whooping cranes [200]. Yellow rail build nests in water sedge stands along the shore of Lake St. Francis, Quebec [179].
In late July 1986, Kerbes and others [112] identified up to 22 lesser snow geese nests/3.7 acres in C. a. var. stans and C. a. var. aquatilis stands on the west coast of Hudson Bay near Eskimo Point, Northwest Territories.
In Montana and Washington wetland and riparian zones, water sedge provides good cover for waterfowl, small nongame birds, and small mammals [35,87,88,120]. White spruce/bog birch/water sedge communities provide cover for a variety of rodent species in Kluane National Park, Yukon Territory [122].
In Montana, water sedge communities are often found adjacent to waterways supporting trout. The dense sod created by water sedge hangs over streambanks, creating valuable cover and shade for fish [86].
In the High Arctic, approximately 10% of water sedge's aboveground green tissue survives over winter. In spring, water sedge shoots present grow rapidly, reaching maturity (late June to early July) in 30 to 35 days of the 50- to 55-day growing season [33]. Water sedge continues to produce new shoots during late June to late July in the High Arctic, but at a lesser rate than in May [27].
In Alaska, C. a. var. aquatilis plants produce all their leaves by late June in a hot springs environment, while C. a. var. aquatilis plants in a permafrost environment do not mature fully until late August. The hot springs plants show 3 times the rate of vegetative growth and 5 times the rate of flowering of permafrost plants [44]. C. a. var. stans plants on Ellesmere Island, Northwest Territories, have a growing season from the last week of June to the 1st week of August [173].
The flowering period for water sedge is presented below:
Location Flowering period Idaho July to September [116] Utah (Uintah Mountains) June to August [80] New England June to July [185] Pacific Northwest June to August [96] Yukon Territory (Sheep Mountains) 25 May to 10 June [97] Canadian Arctic Archipelago June to July [131]Water sedge recovers from fire by rhizomatous spread and/or establishing from seed [119,120,121,170,186]. Seed dispersal onto burned sites is likely effected by water [161,191] or waterfowl [161]. While water sedge utilizes a seed bank [30,69], as of this study (2006), there is a lack of information on seed tolerance to fire. At the time of this review (2006), there is little information regarding the effect of fire on water sedge. One study, conducted in Alaska, found that fire in a water sedge-white cottongrass community caused a substantial increase in water sedge cover by postfire year 3, and by postfire year 24 cover was over 3 times that of prefire coverage [172]. However, the same fire caused a large decrease in water sedge coverage in an area where it was not dominant [170].
A publication on wetland sites on National Forests of eastern Washington notes that water sedge quickly sprouts following summer or fall fires, when growth is reinitiated in spring [120]. A publication on riparian zone associations in Oregon National forests notes that water sedge is very resistant to fire [121].
Water sedge reproduces primarily by rhizomatous growth [27,31]. Reproduction of water sedge by seed occurs infrequently [33,187].
Pollination: Water sedge is wind pollinated [41].
Breeding system: Water sedge is weakly self-compatible [41]. Most plants are cross pollinated [41]. The upper ends of spikelets on water sedge plants are often monoecious [96,156,214].
Seed production: Fruiting of water sedge may only occur during "favorable" years [145,161]. Each year approximately 6% to 9% of water sedge shoots flower and produce few viable seeds [33].
Seed dispersal: Seeds of water sedge are dispersed by water [161,191] and grazing waterfowl [161].
Seed banking: Water sedge utilizes a soil seed bank [30,69]. On 23 July 1981 and 15 July 1983 soil samples measuring 6Ã6Ã4 inch (15Ã15Ã10 cm) were taken from a tundra site at the southern edge of Alaska's Arctic Coastal Plain. Water sedge seeds were obtained from a planeleaf willow/sheathed cottonsedge (Eriophorum vaginatum) community, a grayleaf willow/entireleaf mountain-avens (Salix glauca/Dryas integrifolia) community, a rope-root sedge-round sedge (Carex chordorrhiza-C. rotundata) community, and a dwarf birch-northern Labrador tea (Betula nana-Ledum palustre) community. Seeds excavated in 1981 were stratified for 6 months at 36 °F (2 °C). The 1983 soils were stored at Â0.4 °F (Â18 °C) for 4 months before being placed in a greenhouse, where they were subjected to a temperature regime ranging from 68 °F to 86 °F ( 20-30 °C). Half of the seeds obtained in 1981 and all of the seeds from 1983 were fertilized with a solution of 15/30/15 N/P/K fertilizer once per month while in the greenhouse. Seeds from the 1981 lot were allowed to grow in a greenhouse for 9 months and seeds from the 1983 lot were allowed to grow for 11 months. The following table describes the number of water sedge seeds (# of seeds/m²±s x) from the 4 community types that germinated under greenhouse conditions [70]:
Community type1981
1983
Unfertilized Fertilized Fertilized planeleaf willow/sheathed cottonsedge ---* 107±86 --- grayleaf willow/entireleaf mountain-avens 18±18 --- --- rope-root sedge-round sedge 160±99 107±86 267±101 dwarf birch-northern Labrador tea 18±18 71±18 55±11 *No dataGermination: Water sedge has a germination rate ranging from 20% to 60% [111]. Water sedge seeds collected in Wisconsin and placed in a greenhouse had a germination rate of 12% [176]. To determine seed germination requirements, so as to restore wetlands with water sedge seeds, a series of experiments was conducted by van der Valk and others [208]. Seeds were collected from Midwest wetlands. Water sedge seeds were approximately 1 month old when subjected to 3 temperature and 2 moisture treatments. Seeds were stored for 4 months under the 3 different temperature regimes, then stored for 5 months at 39 °F (4 °C) before being placed in a greenhouse. Germination rates were best when water sedge seeds were stored in a dry environment for 4 months at 25 °F (Â4 °C). There was no appreciable germination of water sedge seeds 8 months or older in the study. The following table describes the results of the water sedge germination trials [208]:
Temperature treatmentMoisture treatment
Dry Wet Room 22% 53% 39 °F 55% 58% 25 °F 78% 5%Baskin and Baskin [24] describe the dormancy of water sedge seeds as "physiological dormancy."
Seedling establishment/growth: On the upper Mackenzie Delta, Northwest Territories, seedlings of water sedge produced rhizomes and tillers during their 1st year of growth [161].
Asexual regeneration: Water sedge reproduces asexually from rhizomes [15,27,31]. On cryic soils, vegetative reproduction rates of water sedge are slow, resulting in limited expansion. A low rate of expansion is also often associated with deficient soil phosphorus levels [15]. Water sedge rhizome cuttings planted in a Colorado fen had a survival rate of 50.7% two years following planting (see Value for Rehabilitation of Disturbed Sites [53].
Water sedge thrives on disturbed sites [40,145,190,210], is shade intolerant [163,206], and occurs in several stages of succession. On the Colville River floodplain near Umiat, Alaska, water sedge is a pioneer species [32]. As a consequence of global climate change, pockets of boreal permafrost peatlands are thawing, creating "collapse scars." Water sedge is a pioneer species on the edge of collapse scars in northern Manitoba [39]. On the Alaskan tundra, water sedge is a pioneer species in areas where vehicles have created thermokarst (thawing of ice-rich permafrost) landforms [40]. At wetland sites throughout Montana, water sedge is a late seral to "climax" species [85]. On oil spill and abandoned oil drilling sites and roads on the North Slope of Alaska, water sedge is a pioneer species [145]. Water sedge is a secondary successional species in wetlands on Mount St. Helens, Washington, 14 years after the 1980 volcanic eruption [201]. On sites severely burned by the 1988 Greater Yellowstone Ecosystem fire, water sedge occurs as a pioneer species [3]. In the low and high arctic, water sedge can be found on pioneer sites, but water sedge is also part of the stable, "climax" vegetation [31].
In northwestern Canada, water sedge naturally colonized borrow pits created during the construction of the Dempster Highway and the Canadian Oil pipeline system [114].
The currently accepted scientific name of water sedge is Carex aquatilis
Wahlenb. (Cyperaceae) [4,36,62,63,64,79,80,95,96,106,107,109,125,128,143,181,211,213,214]. There are 3
recognized varieties:
Carex aquatilis var. aquatilis Wahlenb. [101,106,107,181]
Carex aquatilis var. dives (Holm) Kükenth [106]
Carex aquatilis var. stans (Drej.) Boott [101,106]
Throughout this review Carex aquatilis refers to the species as a whole.
Carex aquatilis var. aquatilis, C. a. var. dives, and C. a. var. stans
are referred to by their full scientific names when citing literature that distinguishes varieties.
Water sedge is an excellent species for stabilizing streambanks due to its strong rhizomatous growth [85,86]. In Montana and Washington riparian and wetland sites, water sedge has medium erosion control and short-term and long-term revegetation potential [35,87,88,120]. A cultivar of water sedge is commercially available [205].
In 1986, two wetlands that had been destroyed by highway construction were restored in the Upper Mud Lake wetlands complex, Wisconsin. The relative cover of water sedge in the undisturbed reference area was 21.0%, which was significantly (p<0.01) greater than in restored area 1 (7.0%) and restored area 4 (1.0%). The reduction in cover of water sedge in the 2 restored wetlands was primarily due to a loss of peat and an unstable hydrologic regime [14].
On the north coast of Devon Island in the Canadian High Arctic, clonal transplants of C. a. var. stans were successfully used under 2 moisture and planting regimes to revegetate tire ruts in the tundra. Two study plots with 2 different treatments were established on Devon Island. Plot 1 was planted with 55 vegetative shoots of C. a. var. stans with the gaps between the shoots filled in with sod containing 3 bryophytes (giant calliergon moss (Calliergon giganteum), limprichtia moss (Limprichtia revolvens), and meesia moss (Meesia triquetra)) to bring the ruts up to the level of surrounding undisturbed tundra. Plot 2 was planted with 45 vegetative shoots, and the gaps were not filled with sod. Plot 1 had water flowing through the ruts on a seasonal basis, and plot 2 was completely covered in standing water. Nineteen years following planting, on plot 1, the mean percent cover of C. a. var. stans was 21.4% in the restored site and 28.6% on the undisturbed control site. On plot 2, the mean percent cover of C. a. var. stans was 18.0% on the restored site and 14.4% on the undisturbed control site [74].
In the southern Rocky Mountains of Colorado, water sedge was used to revegetate mined peatlands. Water sedge seedlings were collected from the field in late fall 1991 and early spring 1992, and germinated in a greenhouse in April 1992. While the seeds were germinating, rhizome cuttings from a healthy population of water sedge were collected from High Creek fen. In June 1992, 270 water sedge seedlings and rhizome cuttings were planted in 27 study plots. Water sedge seedling and transplanted rhizome survival rate was greatest where the water table was within 4 inches (10 cm) from the soil surface or where there was shallow standing water. By August 1994 the survival rate for seedlings and rhizome cuttings was 50% and 51%, respectively [53].
Survival rate (%)
August 1992 June 1993 August 1993 August 1994 Seedlings 95.2 67.0 63.0 50.3 Rhizomes 91.4 79.6 68.9 50.7Several studies have investigated the impact of oil drilling activities on water sedge communities in northern Alaska and Canada [34,69,73,94,113,115,145,180].
Carex aquatilis is a species of sedge known as water sedge and leafy tussock sedge. It has a circumboreal distribution, occurring throughout the northern reaches of the Northern Hemisphere. It grows in many types of mountainous and arctic habitat, including temperate coniferous forest, alpine meadows, tundra, and wetlands.
There are several varieties of this species, and it is somewhat variable in appearance. It produces triangular stems reaching heights between 20 cm (8 in) and 1.5 m (5 ft), and generally does not form clumps as some other sedges do. It grows from a dense rhizome network which produces a mat of fine roots thick enough to form sod, and includes aerenchyma to allow the plant to survive in low-oxygen substrates like heavy mud.[1] The inflorescence bears a number of spikes with one leaflike bract at the base which is longer than the inflorescence itself. The fruits are glossy achenes, and although the plant occasionally reproduces by seed, most of the time it reproduces vegetatively, spreading via its rhizome.[1] In fact, in any given year, most shoots produce no flowers.[1] This perennial plant lives up to 10 years or more, can form peat as its rhizome system decomposes, and is sometimes used to revegetate areas where peat has been harvested.[1]
Carex aquatilis is a species of sedge known as water sedge and leafy tussock sedge. It has a circumboreal distribution, occurring throughout the northern reaches of the Northern Hemisphere. It grows in many types of mountainous and arctic habitat, including temperate coniferous forest, alpine meadows, tundra, and wetlands.
There are several varieties of this species, and it is somewhat variable in appearance. It produces triangular stems reaching heights between 20 cm (8 in) and 1.5 m (5 ft), and generally does not form clumps as some other sedges do. It grows from a dense rhizome network which produces a mat of fine roots thick enough to form sod, and includes aerenchyma to allow the plant to survive in low-oxygen substrates like heavy mud. The inflorescence bears a number of spikes with one leaflike bract at the base which is longer than the inflorescence itself. The fruits are glossy achenes, and although the plant occasionally reproduces by seed, most of the time it reproduces vegetatively, spreading via its rhizome. In fact, in any given year, most shoots produce no flowers. This perennial plant lives up to 10 years or more, can form peat as its rhizome system decomposes, and is sometimes used to revegetate areas where peat has been harvested.
