Lecture 5 Flashcards
T/F: the HBL forest region is the only one on the HBL physiographic region
F: it includes the tundra as well
Why does the southern HBL have continuous forest?
- Glaciers left earlier
- higher elevation + better drainage
- more opportunity for forest to develop
- flat due to isostatic rebound
Bedrock in the HBL
Sedimentary rock (limestone)
Elevation of the HBL
- low (60-150m ABS)
- southern part is more elevated
HBL’s average daily temp. + its effects
between -3C and -6C
- short growing season
- discontinuous permafrost
- cold + wet conditions are ideal for sphagnum moss
- effect of the Tyrrell Sea
What results in the HBL having poor drainage?
- discontinuous permafrost
- flat land
- impervious deposits
T/F: Sphagnum moss creates its own soil where there is none, and forms peatlands
True
T/F: the HBL is one of the largest expanses of continuous wetland in the world
True
Bog
Peatland where nutrients arrive through rainfall; nutrient-poor compared to fens
Fen
Peatland where nutrients arrive through moving water (brought from the land); nutrient-rich
T/F: It’s impossible for a bog to become a fen, or vice versa
F: can change if the method of how nutrients are brought in changes
Sedges
Grass-like (but with a triangular stem, not a round one); can colonize/grow out into water by attaching to shore and stems growing into the water
How does a peatland form?
Sphagnum moss grows around sedges and dominates the area, changing its characteristics
Effects of sphagnum moss
- Changes physical/chemical attributes of the area
- Releases acids
- Locks up nutrients; deprives area of nutrients
- forms a mat on top of water, depriving the area of oxygen
How does a mat of sphagnum moss get thicker through time?
- Little decomposition occurs due to cold, so growth > decomposition
- Gets thicker, locking up nutrients and preventing the system from giving off oxygen
Structure of sphagum
Living & dead cells joined in a chain; can soak up water from the bottom to provide it to the mat’s surface
What does sphagnum do to habitats?
Makes them cold, wet, oxygen-poor
Peat
Partly-decayed bottom of the mat of sphagnum moss - this is the “soil” they form
What is peat called when it’s >45cm thick and wet?
Muskeg
What trees characterize HBL muskeg?
Stunted black spruce & tamarack
Plants that grow on muskeg
- Lichens (e.g. reindeer lichens)
- Heath plants (e.g. bog laurel/rosemary, cranberries, labrador tea, leatherleaf)
What features of heath plants let them survive in muskeg?
- Leathery leaves w/hairs on the bottom (prevent dessication in the winter)
- Leaves are retained to conserve nutrients
- Mycorrhizal associations on the roots draw in nutrients
3 types of traps for carnivorous plants + examples
- Pitfall traps (pitcher plant)
- Adhesive traps (sundews)
- Suction traps (bladderwort)
What are the most common type of shrubs around peatlands? What advantage do they have in getting nutrients?
Alders - root nodules filled with nitrogen-fixing bacteria help them get nutrients
