Ministry of Environment
Sensitive
Ecosystems Inventories
Wetlands of East Vancouver Island and the Gulf Islands
Wetland ecosystems are characterized by seasonal or year-round water, either at or above the soil surface or within the root zone of plants. They are found in areas of flat, undulating terrain and colder wetter climate.
Wetlands encompass a range of plant communities which includes western redcedar/skunk cabbage swamps, cattail marshes, Sphagnum moss dominated bogs and coastal salt marshes. The six Wetland classes recognized by the SEI include:
- Bog (WN:bg). Bogs are acidic, nutrient-poor wetlands
that characteristically support Sphagnum mosses and ericaceous shrubs
such as Labrador tea and bog-rosemary. Being generally isolated from
mineral rich groundwater or surface water, their primary source of
water and nutrients is from rainfall.
- Fen (WN:fn). Underlain by sedge or brown moss peat,
fens are closely related to bogs. In addition to rainfall, fens receive
mineral and nutrient-enriched water from upslope drainage or groundwater.
Thus a broader range of plants, including shrubs and small trees,
is able to grow.
- Marsh (WN:ms). Marshes are characterized by permanent,
seasonal or diurnal flooding of nutrient-rich waters. They include:
freshwater marshes which are dominated by rushes, sedges and grasses;
saltwater marshes; and estuarine marshes occurring at the mouths of
most of the major rivers.
- Swamps (WN:sp). Swamps are wooded wetlands dominated
by 25% or more cover of flood-tolerant trees or shrubs. Characterized
by periodic flooding and nearly permanent sub-surface waterflow through
mixtures of mineral and organic materials, swamps are high in nutrient,
mineral and oxygen content.
- Shallow Water (WN:sw). Shallow Water Wetlands are
characterized by water less than 2 m in depth in mid-summer, support
less than 5% rooted vegetation. They serve as important habitat for
waterfowl and support fish, insects and amphibians.
- Wet Meadow (WN:wm). Wet Meadow wetlands receive water from run-off or seepage, and provide a grassy overall mixture of flood tolerant grasses, low sedges, rushes and forbs.
Wetlands often occur as mosaics of several classes or are transitional between two classes. In addition, Wetlands may occur in complexed units with other ecosystems such as Seasonally Flooded Agricultural Fields (FS), Riparian (RI) and Older Second Growth (SG).
Wetland ecosystems account for 1.7% of the entire SEI area or 22% of the total area of sensitive ecosystems. They are more commonly found in the northern part of the SEI study area (Comox-Strathcona, and Nanaimo Regional Districts).
Values and Ecological Attributes of Wetlands
Wetland ecosystems are the most productive environments in the world. They provide critical habitats for many rare species and plant communities due to their extreme productivity as feeding areas and support of a high number of habitat niches. In addition, wetlands play important roles in maintaining water quality via biofiltration, and the regulation of rainfall run-off by acting as storage sites for surface water.
Conservation Concerns for Wetlands
Direct impacts such as draining, filling or dyking, are responsible for the loss of or disturbance of vegetation or soils in a wetland.
Indirect impacts such as changes to hydrology due to urban development, agriculture and forestry activities, have the most significant effects on wetlands. Additional indirect impacts include increased disturbance from recreational access, nutrient level changes from urban run-off and the introduction of invasive species.
Climate change could have devastating impacts on wetland ecosystems on the east coast of Vancouver Island.
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