Wetlands are places where aquatic and terrestrial habitats meet. They are either permanently or seasonally wet, and support plants adapted to wet conditions. Labrador has large and widespread wetlands, especially bogs and fens, as well as smaller coastal and estuarine wetlands. Read more
Wetlands are highly productive and biologically diverse habitats that provide ecological and economic services such as habitat for plants and animals, improved water quality, water storage, flood and erosion control, and carbon sequestration. Wetlands are some of the most depleted ecosystems on earth; with over ½ of global wetlands already converted to human uses. Canada is the steward of about ¼ of the world's wetlands.
Five classes of wetlands occur in Labrador:
Bogs are organic wetlands with thick accumulations of weakly decomposed peat at least 40 cm thick. They are nutrient-poor, receiving nutrients through atmospheric precipitation, and supporting fewer species than other wetland types (oligotrophic) (NWWG 1997, Meades 1990, Riley 2011). Bogs are dominated by red and brown Sphagnum mosses, such as S. rubellum and S. fuscum, ericaceous shrubs such as Sheep Laurel and Leatherleaf, and lichens of the genus Cladonia (Mahoney et al. 2007). The trees occurring on bogs are Black Spruce, with some Tamarack. Bog pools have even fewer vascular plants, such as Buckbean (Menyanthes trifoliata), Carex limosa and C. oligosperma, and black mosses (Goudie and Whitman 1987). Palsa bogs are found throughout the permafrost zone south to the Porcupine Strand. These ice-cored wetlands are vulnerable to disturbance, particularly trampling, which can damage the insulating moss and lichen layers, causing melting and collapse (Goudie 2004).
Fens are more nutrient-rich and receive added nutrients through lateral seepage of waters in contact with the underlying sediments (minerotrophic) (Goudie 2004, Meades 1990). They occur as stand-alone peatlands or in combination with bogs, or along pond and lake margins (Goudie and Whitman 1987). Fens support more species than bogs and are often dominated by sedges and brown mosses, with fewer Sphagnum mosses than bogs. Typical plants include Newfoundland Dwarf Birch (Betula michauxii), Sweet Gale (Myrica gale), Bottle-brush (Sanguisorba canadensis), TaIl Meadow-rue (Thalictrum polygamum), New York Aster (Aster novi-belgii), Dwarf Raspberry (Rubus acaulis), Spatulate-leaved Sundew (Drosera intermedia), Bladderwort (Utricularia vulgaris), and Club Spikemoss (Selaginella selaginoides) (Goudie and Whitman 1987, Meades 1990, Wells and Hirvonen 1988).
Peatlands often contain both bogs and fens, and are difficult to map remotely, because local patterns relate to subtle changes in basin microtopography and slope. Patterns include “string” and “pool” forms, with bogs occupying raised, ribbed and drier sites, and fens the lower, wetter sites (Mahoney et al. 2007). Linear hummocks are usually terraced perpendicular to basin slope (NWWG 1997). In Labrador, fens are particularly frequent north and west of the Smallwood Reservoir (Riley et al. 2013). Labrador peatlands are notable for their patterned fens and fen-bog complexes, which provide important breeding habitat for waterfowl and Canada Goose. Patterned fens also support higher diversity and densities of waterfowl (Goudie and Whitman 1987). Plants common to both bogs and fens include Bog Rosemary (Andromeda glaucophylla), Leatherleaf, Bog Laurel (Kalmia polifolia), Labrador Tea, Pitcher Plant (Sarracenia purpurea), Round-Ieaved Sundew (Drosera rotundifolia), Small Cranberry (Vaccinium oxycoccos), Buck bean (Menyanthes trifoliata), and Deer Grass (Scirpus caespitosus) (Meades 1990).
Freshwater marshes are mineral wetlands with little or no peat accumulation. They are nutrient-rich, and are found next to periodically flooded rivers, ponds and bays. Marshes are mostly non-wooded, and vegetation is grassy in appearance, being composed primarily of sedges, rushes, and grasses (Meades 1990). Plant species characteristic of freshwater marshes include Sweet Gale (Myrica gale), Red-Osier, Swamp Birch (Betula pumila), Blue Flag (Iris versicolor), Tall Meadow-Rue (Thalictrum polyganum), Bluejoint grass (Calamagrostis canadensis), Bur-reeds (Sparganium spp.), Horsetails (Equisetum spp.), and sedges (Carex utriculata, C. lasiocarpa, C. oligosperma, C. aquatilis) (Meades 1990). Large freshwater marshes are limited in Labrador (NWWG 1997). They fringe the shores of Lake Melville (Lopoukhine et al. 1978), Smallwood Reservoir (Wells and Hirvonen 1988), and lake and river margins in the Eagle, White Bear, North, and English rivers and elsewhere in southern Labrador (Goudie 2004, Wells and Hirvonen 1988). Seasonal flooding often defines their extent, and they are also often created by beaver dams. They are important for geese and dabbling ducks, especially the rich fluvial marshes of Flatwater Brook, which support hundreds of moulting male Black Duck (Goudie and Whitman 1987). This is one of only a few moulting sites for Black Duck identified in Labrador. Rich river deltas supporting extensive fluvial marshes occurring within the Seal Lake area, particularly Snegamook Lake, are also important for breeding and moulting waterfowl (Goudie 2004).
Swamps are nutrient-rich, mineral wetlands adjacent to seasonally inundated rivers, streams or ponds. They are dominated by Alder (Alnus spp.) and Willow (Salix spp.) and generally have rich herb understoreys. Other shrubs like Mountain Maple (Acer spicatum) are rare. Scattered trees can include Balsam Fir, White Spruce, White Birch, and Balsam Poplar. Conifer swamps are less common (Mahoney et al. 2007, Meades 1990). In Labrador, swamps are restricted in their overall extent. Important swamp areas flank the large rivers in the Seal Lake and Eagle River areas, and support rich habitat for breeding and moulting waterfowl. Extensive shrub swamps interspersed with fluvial marshes are found along the network of lakes, ponds and peatlands on the Eagle Plateau, especially along the Paradise River. Swamps are particularly abundant on lake deltas and river meanders (Goudie and Whitman 1987, Goudie 2004).
Shallow open water wetlands have submerged aquatic plants growing within a waterbody less than 2 m deep (Mahoney et al. 2007, Meades 1990). Vegetation includes totally submerged and/or floating-leaved species such as Yellow Pond Lily (Nuphar variegatum), Bladderwort, Mare's Tail (Hippuris vulgaris), Water Millfoil (Myriophyllum alterniflorum), Pondweeds (Potamogeton spp.), and Quillworts (Isoetes spp.) (Meades 1990).
Wetlands can be further classified based on surface terrain, patterning, or physiognomy. In Labrador, ecodistricts rich in peatlands include St. Paul (20% of total area), Atikonak Lake (19%), Eagle Plateau (17%), Melville Lowland (14%), North Michikamau (13%), and Joseph Lake (12%).
No wetland inventory is available for Newfoundland and Labrador. Some data have been collected through Environmental Impact Statements (EIS), but are often out of date, and many researchers note the need for a comprehensive wetland inventory.
Land cover such as the Earth Observation for Sustainable Development of Forests (EOSD), the Drieman-Curtis Index and the Forest Resource Inventory include broad wetland classes but wetlands are not the focus of these classifications. In 2007, the Canadian Wildlife Service surveyed an area of the Eagle Plateau, just east of Minipi Lake, identifying various wetland types. A comparison between this work and other land cover datasets showed that none accurately identified swamps and marshes, whose extent is notably underestimated in Labrador. Conifer swamp is a major element of boreal wetlands, but further work must be done to map their extent in Labrador. In the case of salt marsh, some mapping has been completed but is not yet available digitally.
In the absence of detailed wetland surveys, but applying findings from other boreal regions, wetlands of particular conservation interest should include, at a minimum, wetlands that are distinctive, diverse and productive, including salt marsh, freshwater marsh, open fen, and thicket swamp. Quebec uses waterfowl abundance as an indicator of wetlands of conservation interest. Habitat data have been combined with 15 years of Eastern Waterfowl Survey (EWS) data on breeding waterfowl to predict important areas in the southern boreal (see Lemelin et al. 2008). Other metrics related to high-value wetlands are watershed-level intactness, or the absence of human disturbance, wetland size, and wetland density.
Wetland density is a measure of the extent of wetlands as a percentage of the total area (per km2). Areas with a vaue of 100 percent are areas entirely occupied by wetlands, while those with a value of 0 percent have no wetlands at all. Ecodistricts with the highest wetland densities include: Eagle Plateau, St. Paul, North Michikamau, Atikonak Lake, Lac Joseph and Goose River.
The largest wetland in Labrador is occurs near Woods Lake, north of the Smallwood Reservoir, and is 96 km2 in size. Average wetland size is less than one km2. Other large wetlands are found west of Lac Joseph (88 km2), south of Fraser Lake (76 km2), southeast of Ossokmanuan (65 km2), and in the Eagle (80 km2) and St. Paul River headwaters. These are also areas of high wetland density, with many wetlands adjacent to one another.
Wetland edge-density measures wetland edges, both the aquatic-terrestrial ecotones of the external edges of wetlands, as well as the internal edges created by pools of open water. Wetland edge-density is measured in km/km2. The highest wetland edge-density in Labardor is nearly 69 km of edge per square kilometer. Biodiversty is often greatest at ecotones, and wetland edge-density may be a useful metric for biodiversity planning.