Ecosystems and habitats

Wapusk National Park represents Hudson-James Bay Lowlands, a vast, low-lying plain on the western shores of Hudson Bay. The land is a flat, poorly drained coastal plain with many lakes, ponds, creeks and meandering rivers that cover half of the land’s surface. The plain is influenced by a maritime subarctic climate and covered by the most extensive mantle of muskeg in North America. Located between latitudes 51ᵒ and 65ᵒ North, the lowlands contain one of the world’s largest contiguous wetlands.

The park is a transitionary ecosystem with boreal forest in south and arctic tundra to north. The current landscape developed as a result of isostatic rebound. This means that the land masses are rising after ice sheets pushed them down during the last ice age. This process is happening at a rate of approximately 1.3 metres every 100 years. The region is underlain by continuous and discontinuous permafrost and impermeable silt-clay soils. These features impede water infiltration and cause pooling of water at the surface. This creates the wetlands and thousands of lakes that aerial views of Wapusk are known for.

Wapusk National Park plays an important part in habitat conservation. Wapusk protects one of the world's largest known polar bear maternity denning areas. The park preserves critical habitat for hundreds of thousands of waterfowl and shorebirds. These birds nest on the Hudson Bay coast in the summer and gather to feed during the spring and fall migrations.

Ecosystems

The park is divided into six unique ecotypes:

• Coastal fen
• Coastal ridges and fen
• Transitional fen
• Interior peat plateau
• Coastal forested fen
• Forested peat plateau

The coastal fen ecotype is dominated by sedge and rush vegetation. Lakes within this ecotype form in depressions between beach ridges or in depressions caused by thawing permafrost.

The interior peat plateau ecotype contains moss, lichen and small shrubs. Approximately two to three metres of peat is underlain by roughly 70 centimetres of continuous permafrost. Lakes within this ecotype are primarily thermokarst in origin with ice-wedge peat polygons as their dominant features.

The boreal spruce forest ecotype is dominated by lichens, sphagnum moss, black spruce, tamarack, shrub willow and birch. Lakes within this ecotype are predominantly thermokarst in origin.

The thermokarst terrain type is characterized by very irregular surfaces or marshy hollows and small hummocks as ice-rich permafrost thaws. The land surface type occurs in Arctic areas and, on smaller scale, in mountainous areas.