Unit 3: Northern Biogeography Flashcards
What is the primary factor that determines the northern limits of tree growth?
The lack of summer warmth. Without it, plant tissue doesn’t have the time to grow. Plants can’t afford the energy.
Describe the process of succession as it relates to Subarctic plants and soil.
- Succession starts: Under bare, open, sunlit soil, the permafrost table lies deep, leaving the surface a hospitable habitat for trees.
- When the trees grow big enough to form a closed canopy, the ground becomes shaded and is soon covered with dead leaves and needles. In time, a carpet of moss develops as well (good insulator).
- As the soil becomes more and more insulated, the soil gradually cools, and the permafrost table rises until the ground is no longer suitable for trees growing on it.
- As the trees die, they are replaced by stunted trees which can grow on the thinner layer of active layer and on soil made acidic by plant remains.
- The new trees are too widely placed to shade the ground, so new tundra plants can grow in between them. Dense carpet of lichen often develops. Succession is finished.
What factors other than cold do plants need to adapt to in order to survive in the Arctic?
- short growing season
- drought
- frost-heaving
- strong winds
- infertile soil
What is a drunken forest and what causes it?
It is an area where the vertical alignment of trees has been disrupted by the thaw and freeze of permafrost, causing them to lean like they were drunk. Thermokarst (ground slump caused by permafrost).
Is the tundra a carbon sink or source?
The tundra absorbs more carbon than it gives off, bringing about a net reduction in the amount of carbon dioxide in the atmosphere, therefore making it a carbon sink.
This is because most of the carbon gets locked away in peat in the cold since things can’t decompose as easily.
If global warming raised enough to reheat, it could become a carbon source, enhancing the greenhouse effect.
What is unique about the Arctic woolly bear?
Unlike southern caterpillars that reach maturity in a few weeks, this guy takes 10 years since it has such as limited feeding window. It produces lots of antifreeze to survive multiple polar winters.
Explain the adaptations of the Caribou.
- Unique hooves shaped like shovels that help them dig food up through snow.
- Thick, blunt snout that houses a heat exchanger for air.
- Slender legs have heat exchange system of veins and arteries to prevent heat loss.
- Dense two-layer overcast that traps warm air insulated around the body.
- Can sniff found beneath 70cm of snow
- can recycle, resynthesizes, and store nutrients from digestive system in times of food scarcity.
- Draw on fat deposits in emergency (e.g. blizzard).
- Slow their metabolic rate by 30% to preserve essential functions.
What is refection?
Snowshoe hare can sustain itself temporarily by eating partially digested droppings which can stretch limited food resources.
Explain some of the adaptation made by migratory birds to the short summers.
Moult migrations (they will move from the main area to help preserve food supplies)
Early Nesting
Rapid Development
Diversified diets
Leaving early (parents leave as soon as chicks can fend for themselves)
Thirst (1. feed on high fat; 2. specialized breathing to minimize water loss).
What is anadromy?
It is a migratory lifestyle involving breeding in freshwater and growing in saltwater. A practice that increased with latitude.
How do birds protect their feet from the harsh cold of the Arctic?
Counter-current heat exchange (like caribou). Overlapping veins and arteries warm up as blood passes through. They send only enough blood to the feet to keep them from freezing and they keep as much blood in torso.
What are the differences between altricial species, precocial species, and semialtricial and semiprecocial birds?
Altricial: Hatchling nest and entirely depend on parents (e.g. naked, blind, immobile), but mature the fasted to adulthood.
Precocial: Hatchling start more mature and independent (e.g. can wander with parental guidance, downy).
Semiprecocial: They stay in the nest despite their advanced development
Semialtricial: they are immobile and need to be fed, but are downy and open eyed.
What makes a phalarope unique?
usually, the male of the species is larger, more colourful, more dominant. Phalaropes are the opposite; the female is bigger, prettier, and in charge. Males take on egg responsibility, while females defend territory.
Discuss some of the adaptations to Arctic conditions that are observable in capelin eggs.
- outer shell has an additional thick, sticky layer to keep out ice crystals.
- eggs are continuously surrounded by film of seawater which prevents freezing inside the egg.
Why are Arctic marine waters more productive than fresh waters?
Marine waters in the Arctic are more productive than fresh waters because they contain a higher concentration of the basic nutrients that are necessary for the growth of phytoplankton. In turn, these tiny protists support an entire food web and their quantity determines the abundance of fish that live there.
