Many writers have called wetlands the kidneys of the earth because they filter and clean the water that flows through them. But they are also the bladders of the earth by virtue of their water storage ability. For their role in transforming nutrients, wetlands are also the earth's digestive tract, and for their ability to filter toxins, they are the liver as well.
— Linda Nowlan and Bill Jeffries
There are many types of wetlands (swamps, marshes, bogs, fens, seeps…) and their nuances can become complicated. Really, the name says it all: land that is wet. Some wetlands are covered in shallow water year-round, whereas others are wet for only a few months out of the year. The distinguishing features of wetlands are water-loving vegetation, and soil formed under low-oxygen conditions. Estuaries
and salt marshes
are special types of wetlands that are located at the interface between fresh and salt water; these are treated in detail elsewhere (see links above). Although the definitions of wetlands and riparian zones
overlap somewhat, riparian zones occur alongside streams and water bodies only.
Wetlands were long considered “waste” areas, full of undesirable pests, unsuitable for building on, and useful only once they had been filled in and converted to “practical” land uses. Consequently, a great many wetlands have been abused and destroyed. Now, they are being valued once again for the useful services they perform as functional ecosystems, such as: water supply and regulation of flows; water purification; prevention of downstream and shoreline erosion; maintenance of biodiversity; provision of wildlife habitat; recreational, educational and cultural opportunities; and in some cases production of medicinal and food plants.
Did you know?
- Since 1800, 20 million hectares (about 15%) of Canada’s wetlands have been filled in and lost to development. Near major cities and towns, 70% of wetlands have been lost.
- When one hectare of wetlands is converted to agricultural land, between 1 and 19 tonnes of carbon dioxide (a greenhouse gas) are emitted to the atmosphere per year.
- Most wildlife in the province use wetland habitat at some point in their life cycle.
- Wetlands cover about 6% of the land in BC
- One hectare (100m x 100m) of wetland can store between 9 and 14 million liters of water.
- Wetlands perform many important “ecosystem services” that have been estimated to be worth $14,785 (1994 US$) per hectare, per year.
What lives in wetlands?
Wetlands are home to an enormous variety of plants and animals. The main distinguishing feature of wetland plants is their ability to flourish in saturated soil and to tolerate flooding to various degrees. The types of plants that can grow in any specific area depend on a number of factors, including: the water level and water flows, and how much these vary over the seasons; the underlying geology (rock and mineral content of the soil); and the acidity (measured by the pH) of the site. In dynamic wetlands, where the water level fluctuates both vertically and laterally, nutrients are generally plentiful and decomposition occurs rapidly. These wetlands include swamps and marshes. In wetlands with stagnant or sluggish water, oxygen is limited, plant material decomposes much more slowly, the soils often become acidic and peat forms. These are the conditions that form bogs and fens. Shallow-water wetlands are another type of wetland permanently flooded by still or slow-moving water. These wetlands are often located in the shallow zones of lakes and ponds. Some of the plants that live in these different types of wetlands are described below.
These wetlands are dominated by Sphagnum
peat mosses, which soak up large quantities of water, and create acidic conditions. Other plants that may be found in bogs on southeastern Vancouver Island include:
- Mosses such as ribbed bog moss (Aulacomnium palustre), black fish hook moss (Schistidium apocarpum), and hoary rock moss (Racomitrium lanuginosum)
- Herbaceous plants such as narrow-leaved cotton-grass (Eriophorum angustifolium), white bog orchid (Planthera dilatata) and bunchberry (Cornus canadensis)
- Shrubs such as Labrador tea (Ledum groenlandicum), crowberry (Empetrum nigrum), sweet gale (Myrica gale), bog cranberry (Oxycoccus oxycoccos) and bog blueberry (Vaccinium uliginosum)
- Trees, often in dwarf form, such as lodgepole pine (Pinus contorta) and (more rarely) western redcedar (Thuja plicata)
Fens are not as acidic as bogs, and contain more mineral-rich groundwater. Fens have some water flow through them at least seasonally, and are the most common type of wetland in British Columbia. Sedges (Carex
spp.) are the dominant plant type in fens. Other plants found in fens on southeastern Vancouver Island include:
- Mosses such as tall clustered thread moss (Bryum pseudotriquetrum) and spear moss (Calleirgonella cuspidata)
- sedges such as white-beak rush (Rhynchospora alba) and Dulichium (Dulichium arundinaceum)
- peat mosses of the Sphagnum genus
- herbaceous plants such as bog St. John’s wort (Hypericum anagalloides), buckbean (Menyanthes trifoliata) and purple marshlocks (Comarum palustre)
- shrubs such as hardhack (Spirea douglasii) and sweet gale (Myrica gale)
Marsh wetlands are flooded permanently (to varying levels) or seasonally, and are often dominated by one or two plant species, especially (in this region) by cattail (Typha latifolia
) or hard-stemmed bulrush (Scirpus lacustris
). Other species may include Pacific water-parsley (Oenanthe sarmentosa
), small bedstraw (Galium trifidum
) and sedges (Carex
Swamp wetlands are distinguished by the presence of trees, which are usually absent in most other wetland types. On southeastern Vancouver Island, the dominant trees are usually red alder (Alnus rubra
) or western red cedar (Thuja plicata
). Shrubs such as willow (Salix
spp.), salmonberry (Rubus spectabilis
), huckleberry (Vaccinium
spp.) and red elderberry (Sambucus racemosa
) may be present. Understorey plants include skunk cabbage (Lysichiton americanum
), horsetail (Equisetum
spp.), lady fern (Athyrium filix-femina
), false lily of the valley (Maianthemum dilatatum
) and tree moss (Climacium dendroides
Shallow water wetlands
These wetlands are permanently flooded, and have aquatic vegetation such as floating-leaved pondweed (Potamogeton natans
), yellow pond lily (Nuphar polysepalum
), white water-buttercup (Ranunculus aquatilis
), and Robbin’s pondweed (Potamogeton robbinsii
The species of animals that live in wetlands for all or parts of their life cycles are too numerous to list. Directly or indirectly, almost all wildlife depends on wetlands. Some examples of the species most closely associated with wetlands include:
- A multitude of invertebrates, including worms, molluscs, insects and crustaceans, that control ecosystem processes in wetlands and supply food for higher consumers such as birds, mammals and fish
- Birds, many of which nest and/or feed in wetlands at certain times of the year, including many species of seabirds, shorebirds and waterfowl, Great Blue Heron (Ardea herodias), Canada goose (Branta canadensis), mallard (Anas platyrhynchos), Red-breasted Merganser (Mergus serrator), Common Goldeneye (Bucephala clangula), scaup (Aythaya spp.), Osprey (Pandion haliaetus), plover (Charadrius spp.), sandpipers (Calidris spp.), gulls (Larus spp.), owls, kingfishers (Ceryle alcyon), waxwings, wrens, chickadees, swallows, warblers, sparrows and blackbirds
- Frogs, newts, toads and salamanders, many of which are species at-risk
- Mammals such as bats, mice, shrews, voles, muskrats, mink, river otters, beavers, elk, deer and bear, which live or periodically hunt and graze in wetlands
- Many species of fish, including juvenile Pacific salmon and cutthroat trout, which may use wetlands for their first one to three years of life.
Why are wetlands important to ecosystems?
Wetlands provide food and habitat for thousands of species of plants, animals and microbes, making them crucial for maintaining biodiversity. Biodiversity is essentially variety – within the genetic material of one species, between different species and between ecosystems – and is a necessary feature of life on earth. Ecosystems are complex networks of relationships between species. If too many species in an ecosystem become extinct, the overall system becomes vulnerable and may collapse. Biodiversity increases the resilience of ecosystems, making them more able to function despite natural or human-caused disturbances. Even though wetlands are usually a fairly small component of the landscape, they provide a crucial link between many species and between different life stages of one species.
Wetlands are “powerhouses” of energy and life. They are among the most highly productive ecosystems on earth, ranking among coral reefs and tropical rainforests in terms of primary productivity. The biomass produced in the food webs of wetlands in turn nourishes terrestrial and aquatic organisms and ecosystems.
Wetlands are sometimes referred to as “nurseries” since so many animals begin their lives within them. Juvenile fish benefit from the sheltered waters and plentiful food in wetlands. Many species of birds nest in wetlands. Frogs need moist areas but especially the standing water in wetlands in which to lay their eggs and mature as tadpoles. Many insects lay their eggs in water, and their life cycles include an aquatic larval phase. Insect larvae are in turn important fish and bird food.
Wetlands play an important role in regulating the quality and flows of fresh water, which improves ecosystem function. Wetlands act as “sponges” that soak up excess rainwater during the wet season, and slowly release it in the dry season. As a result, stream flows are maintained even during the summer, and winter (or wet season) flows are less destructive. Stream channels maintain their integrity, riparian vegetation flourishes, and fish and aquatic invertebrates are better able to survive, along with the animals that feed on them.
Finally, wetlands filter the water that flows through them. Microbes break down many potential contaminants, plant roots trap excess sediment, and plants and microbes both reduce excess nutrients such as nitrates and phosphates. Downstream ecosystems including streams, lakes and marine water bodies benefit from improved water quality.
Why are wetlands important to people?
People benefit from wetlands for many of the same reasons as ecosystems do, since we are all interdependent. However, people often equate value to monetary worth; because ecosystem “services” have not been traditionally accounted for in modern economic models, they have often been taken for granted. Nevertheless, even in economic terms, wetlands are valuable ecosystems:
- By regulating water flows, wetlands help to prevent flood damage. The cost (in reduced development and taxation revenue) of preserving wetlands in or near urban areas can be paid back many times over when expensive property damage is prevented.
- Higher property values are associated with proximity to public green spaces such as wetlands, so preserving wetlands can actually increase the value of a new development and offset costs associated with not developing this land.
- By acting as “sponges” that soak up excess water, wetlands help to prevent erosion and property damage along stream banks. This is especially important as new areas are developed and impervious surfaces replace forested land.
- In their role as water purification systems, wetlands serve an important function in maintaining the quality of drinking water, one that would otherwise require purification plants that can cost millions to billions of dollars. They also purify the water we use for recreation and that we rely upon for healthy fisheries.
- As highly productive biological systems, wetlands contribute nutrients required by many commercially important fish and game. As “nurseries,” they are important for the early life stages of many fish and waterfowl.
- Wetlands provide opportunities for recreation, education and community/cultural involvement. The value of these functions is difficult, but not impossible, to assign. For example, in Canada, Mexico and the USA, more than 60 million people participate in bird watching, and 3.2 million hunt waterfowl, generating more than US$20 billion in economic activity per year.
- Wetlands store carbon, in the form of living plants, as well as partially decomposed plant matter (also called peat). In so doing, they prevent this carbon from being released to the atmosphere as carbon dioxide (CO2), a greenhouse gas, and therefore help to moderate the effects of climate change. When one hectare of wetlands is converted to agricultural land, between 1 and 19 tonnes of CO2 are released to the atmosphere per year.
In one of the first comprehensive attempts to apply principles of ecosystem valuation based on services performed by ecosystems (such as those listed above), the authors of a 1997 report estimated, admittedly conservatively, that wetlands have an average value of $14,785 (in 1994 US$) per hectare per year.
Where can I visit wetlands in the Victoria area?
As with many urban areas, many of the wetlands that once existed in the Victoria region have been lost to development. However, a few important areas remain:
- Rithet's Bog is located in Saanich, on Chatterton Way. This bog, used over the years for a variety of agricultural purposes, is now protected as a municipal park, and is maintained with lots of volunteer help.
- Quick’s Bottom Park is in Saanich, and is accessed off Markham Rd. or Wilkinson Rd. This wetland is located in the Colquitz watershed, covers an area of 19 hectares, and includes public walking trails.
- Swan Lake Nature Sanctuary also in Saanich accessed off Saanich Rd. or MacKenzie Ave. The Sanctuary includes the lake and adjacent wetlands, has an interpretive centre, trails and offers many public programs.
- Blenkinsop Lake can be viewed from a bridge that forms part of the Lochside Regional Trail, which connects with the Galloping Goose Regional Trail. Guide to Blenkinsop Lake (PDF)
How can I help protect wetlands?
- Enjoy the accessible wetlands in your area: go on a nature tour, join a bird-watching or native plant group, or just enjoy the peace and solitude of wetlands.
- CRD Nature Programs
- Take your children out in wetlands, or enroll them in a children’s nature program, to learn about the biology of these places; they can also teach us a lot about appreciating the wonders of nature!
- Once you’ve got to know some of your local wetlands a little, make your voice heard to local politicians, to ensure these areas are protected and valued.
- Get involved with a local community stewardship group. They are often looking for people to help out with invasive plant removal, restoration activities, community events, and more.
- If you own property that contains a wetland, consider options to preserve it as an amenity to yourself and other residents and wildlife of the area. See also the resources for streamside and shoreline development and sustainable agriculture.
Additional Information & Links © Image courtesy of L. Townsend