Hudson Bay Lowlands – Natural History (Lecture 5)
-- Boundaries that are encountered include; the Canadian shield (hilly area). At the west is
the boreal forest, the south is Canadian shield (boreal forest), going east is James Bay, while
the Tundra is in the North.
The Hudson Bay Lowlands is one of the wildest untouched parts of the world. There are no
roads there, only planes can access the area. The Hudson Bay Lowland is sometimes called
the “Northern Boreal”. The Hudson Bay lowland is underlain by sedimentary limestone.
This makes the land very flat (low elevation – 60 to 150m). Thus the winds off the Hudson
Bay still have an effect. The average temperature there is -3 to -6 thus a short growing
season. It has discontinuous permafrost. It is also still feeling the effects of the glaciers
(rebound) so land depression. Clay and silt deposits from the Tyrell Sea. Lots of water!
Cold and wet conditions are ideal for sphagnum moss. Sphagnum moss creates a
habitat called a peat land. Peatlands are the dominant habitats in the Hudson Bay
lowlands. When peat >45cm thick and wet it is called Muskeg.
In Ontario we have one of the largest continuous muskeg habitat. How do we tell this from
the Tundra zone? – Trees in the tundra are dwarf, the trees in the Hudson Bay Lowland are
Stunted (black spruce and Tamarack). But the trees grow taller and form continuous forests
in some sites.
Bogs and Fens are two major types of peatland. Bogs receive water and nutrients
only by rainfall and are dominated by sphagnum moss. Fens receive nutrients from
flowing groundwater such as streams and are often sedge dominated.
How do Peatlands form? – they begin by lake fill (moss grows on the edge of the water). It
has helpers (giving it a place to anchor). Sedges colonize and grow out into the water. The
moss mat will grow thicker (forming the soil like habitat). Sphagnum modifies the
environment making it acidic, nutrient poor, and blocks off oxygen (oxygen deprived –
making it hard for other plants to live in). Sphagnum has dead cells that are hallowed that
absorb the water, they are intertwined with
living cells with chloroplasts. They form the
soil. Slowly the mat grows thicker ands
spreads chocking the water. The lower
portion of the moss dies and more moss
grows on top of it.
What type of plants will colonize afterwards? – Lichens, especially Reindeer lichens. Heath
plants are a dominant group (they have mycorrhizal associations – to obtain nutrients on
the roots (fungi). Plants included are the Cranberries and Bog Rosemary. Leather leaf also
has leathery leaves with hairs underneath (to prevent desiccation and conserve nutrients).
Carnivorous plants (sundews (adhesive traps), pitfall (pitcher plants), and bladderworts).