Midterm 1 Flashcards
Vegetation patterns exist in the tundra. Describe: Tussock tundra
Tussock tundra – special type of sedge meadow derived from dense clumps of the cottongrass Eriophorum vaginatum
• Comprise a large portion of carbon stocks
There are 3 zones of the boreal forest, list them.
- Closed boreal forest (southern)
- Open boreal forest (northern)
- Forest-tundra ecotone
In terms of sea ice, define: Shore-fast ice.
coastal regions where ice grows out from and stays attached to the shore
Describe this type of tundra tree: Krummholz
Krummholz – stunted wind-blown trees due continual exposure to fierce, freezing winds causes vegetation to become deformed
Conifers dominate the taiga for many reasons, describe how being an accumulator species contributes.
Most conifers are accumulator species – hoard minerals
• accumulated nutrients aren’t recycled – don’t lose leaves
• fires are often needed to break down dead plant material
Vegetation patterns exist in the tundra. Describe: Sedge meadows.
Sedge meadows: flat or rolling terrain dominated by a mat of grass-like sedge plants
• dense green swards or lawns in imperfectly drained lowlands, dominated by a variety of sedges (Carex sp) and cottongrasses (Eriophorum sp)
•Wettest after snowmelt – drier as summer goes on •Degrade with water pollution and grazing
• related to the open peatlands of the northern boreal forest
What 4 things (basic) are needed for snow crystals to form?
Water Vapor + Ice Nuclei + Cloud Droplets + Temperature <4°C
Define: Kettle hole.
A hollow created when buried blocks of glacier ice melt out.
Conifers dominate the taiga for many reasons, describe how mutalism with mycorrhizae. contributes.
Most taiga plants have mycorrhizae – interweavings of fungal mycelium and root tissue.
Mycorrhizae are a mutualism between plants and fungi.
• the plant provides the fungus with carbohydrates
• the fungus helps the plant get nutrients from the soil, like nitrogen
Describe the Pleistocene Epoch in terms of:
- How many glacial retreats/advances?
- How thick was the ice and how much land was covered?
A glacial period that had up to 20 glacial advances and retreats. There were massive ice sheets (3-4km thick) that covered 1/3 of earth’s land masses.
List the 5 major ice ages that earth has experienced (in order).
- Huronian.
- Cryogenian.
- Andean-Saharn.
- Karoo.
- Quatenary.
- Reading by Dredge*
- What kind of ground was present in the natural environment of Northern Manitoba (pre-ice age). How was this ground formed?
Northern Manitoba (Canadian shield) is a mix of ancient remnants of the earth’s original crust and newer rocks. Old crust was folded through mountain building cycles, while newer crusts was created by volcanic activity (sediments). Most of Churchill’s topography developed in the Late Precambrian time. Limestone makes up much of the sedimentary rock, and is made up of silt or clay sediments and skeletons of calcareous marine organisms.
What are ice wedges, and how does permafrost make them form?
Cold ground contracts in winter, cracks • Cracks fill with water in spring • Freezes and expanded by surrounding permafrost • Forms ice wedges • Repeat. Wedges grow over time.
Are bogs and muskeg’s low or high in nutrients? What is their environment like (temp and nutrients)?
- Low nutrients, but some plants are adapted to this and the chilly soils.
Describe this principle force acting on sea ice:
- Ocean Currents
typically act in the opposite direction of the wind force
• act as a drag on the wind-driven sea ice motion
• important in longer-term ice motion (monthly to
yearly)
Eastern and northern Manitoba’s Boreal Forest and peatlands are exceptionally rich in ___.
Eastern and northern Manitoba’s Boreal Forest and peatlands are exceptionally rich in carbon
Define: Albedo.
What does this influence?
% solar energy reflected back into space (big influence on surface energy).
How much of the world’s freshwater do cryospheres hold?
75%
Describe ice nucleation active (INA) bacteria.
Presence on plant surfaces causes ice nucleation at temperatures 5-8° warmer than in the absence of the INA bacteria.
- Reading by Dredge*
- Today, what is the climate of Churchill (basic)? Is it colder or warmer than previous times, and how can we know this?
- Marine subarctic climate. Most of northeast Manitoba has continuous permafrost (up to 80m thick in Churchill).
- There is evidence of tree migration when warm climates prevailed, and it is believed that trees were present 300km more north compared to now.
Optimal function of enzymes is __-__ C.
Optimal function of enzymes is 37-40 C.
Define: Tree line.
Treeline: northern boundary of the forest-tundra zone
• the zone where ‘forest with patches of tundra’ merges
into ‘tundra with patches of forest’
• the northern limit of the growth of trees that >5m high
• No distinct boundary - gradual change
Has carbon energy pathway to benthic fauna changed over time? Explain this by answering the following question using the Atlantic walrus (a bioindicator).
These walruses are.. • Primarily benthivores • Can consume 57kg of bivalves per day • Central place foragers • Haul-out in large aggregations
2) Is there latitudinal variation associated with different sea ice phenology?
(pretty much just yes or no)
Dependent on latitude and sea ice conditions • Jones Sound – no change, other areas had change.
Boreal forest areas burning is highly episodic with high inter annual variability. Approximately 0.2 - 7.6 million ha are burnt a year. Is this increasing over time?
Yes, and will likely continue to increase with more climate change.
- There are more HUGE fires now compared to before (more area burnt), but smaller fires haven’t changed as much.
First year ice vs multi year ice.
- First year ice forms in grades every year.
- Multi-year ice is a permanent ice zone, may contain younger ice and open water
There are 3 types of fires, surface, crown, and ground fires.
Describe surface fires in terms of what burns/where.
Surface fires: burn fuels at the ground surface
• shrubs, grasses, fallen branches, litter
How do invasive species post a threat to forests?
Invasive species can pose an even greater threat
• no predators, diseases or other natural forces in
Canada to control their population
Define: Minerotrophic.
Fens are minerotrophic – water supply comes mainly from streams or springs.
How are peatlands are growing points for permafrost throughout the taiga?
In summer, sphagnum dries out, insulates against incoming heat
•Sphagnum soils are among the last to thaw in the boreal forest.
In autumn, heavy rains and freeze-thaw cycles: sphagnum becomes water-saturated – conducts outgoing heat
List 5 principle forces acting on sea ice.
- Wind
- Ocean Currents
- Coriolis Force
- Internal Ice Stress
- Sea Surface Tilt
CO2 levels are increasing by __% per year (anthropogenic cause).
1.5%
How does permafrost freeze in winter (ie. from top or bottom?), and how does it thaw? What happens after it thaws?
- Active layer freezes in winter, thaws in summer (top-down)
- After active layer thaws, the water can’t drain
- Can have very wet and boggy ground in summer
- practice exam question *
T or F - Is the rate of ocean heat content now increasing faster?
True!
How (and when) was Lake Agassiz formed?
- Ice sheets blocked meltwater from moving out into Hudson’s bay, and formed a freshwater lake.
- The lake covered most of the mid continent (including Manitoba) for ~5000 years.
- Emptied 8000 years ago when the last ice sheet disintegrated, but left areas depressed by water and ice.
One theory for the reason of more autochthonous lake input (“stuff” coming in from farther places) may be due to more run-off. Is there evidence for increased precipitation, and how would this cause the problem?
• Significant increases in total annual precipitation detected; Trend driven by summer rainfall.
- Precipitation is increasing by +17-19 mm per decade.
List the 3 layers of the nivean environment.
- Subnivean
- Intranivean
- Supranivean
What do climate change models predict in terms of insect outbreaks? What would be detrimental to insect outbreaks (ie. prevent them)?
- Increased temperature increases could increase the risk of future beetle outbreaks
- esp. at high altitudes and latitudes where not as common currently
• Extreme winter weather patterns (e.g., large temperature drops) are detrimental to beetle outbreaks
Describe viruses in sea ice (part of food web).
- High ratio of viruses to bacterias, likely indicating high infection rates but limited information;.
Describe this area within the boreal zone in terms of trees (basic): Forest-tundra ecotone.
transition between
taiga and tundra
What kind of camera can be used to detect infrared (like an animal)?
- FLIR infrared camera.
In terms of glaciers, what is plucking?
Glacier picks up rocks and sediment and deposits it elsewhere.
What forms corn snow?
- meltwater or rain enters the snowpack
- Thawing and freezing cycle = increased vapor migration and freezing lead to large rounded grains
Snow depth/ melt pond coverage largely control light availability in sea ice.
How does attenuation doffer between snow and ice? What is attenuation?
- Snow – 15 m^-1
- Ice – 2m^-1
Attenuation is how easily light can penetrate something. Snow increases attenuation (less light scatter, less light for algal growth).
- Reading by Dredge*
- Describe how Churchill evolved with its 3 major glaciations.
1st: The ice melting created a large lake/sea with clay deposits. Eventually land rose and water receded, leaving tundra-vegetation to cover the area.
2nd: Ice again formed and melted, leaving a sea and vegetation similar to what is seen today (tundra moss, shrub-sedge, birch communities) and animals like woolly mammoths, beavers, snails, and molluscs occupied the area.
3rd: This glaciation brought fossiliferous limestone debris and created the Glacial Lake Agassiz which covered most of the mid-continent.
In terms of formation of snow pack, define: Constructive metamorphism (temperature gradient metamorphism).
New crystals are formed
• Water vapor rises – moves from warmer area near ground
• Water vapor crystalizes as it hits colder temperatures
• With a greater temperature gradient, more vapor is transferred
• More tightly packed near top • Bottom snow layers becomes
loose, less dense, creating crystalline snow = depth hoar
There are 3 types of fires, surface, crown, and ground fires.
Describe ground fires in terms of what burns, and how they form.
Ground fires: burn subsurface organic fuels by smoldering combustion
• often ignited by surface fires
• found in deep peat deposits in a peat bog
• burns most intensely & spreads fastest at the lowest levels
• can move very fast
• may smolder for days to months….then break out on the surface to be fanned by winds into full-scale crown fires
Impacts of disturbances are influenced by spatial factors, temporal, and magnitude.
Describe magnitude.
• Intensity - Physical force of the event
Describe this type of tundra tree: Flagged trees
Flagged trees – branches grow on only one side, due to abrasion by wind and blowing ice crystals.
Reading by Pruitt
Describe this quality of snow cover that affects living organisms: Density.
How does it affect animals (3)?
- It expresses the water content of the snow cover, so dense snow will cause more spring run off.
- Higher density can mean higher insulation for subnivian organisms.
- The insulating properties of density makes the pukak layer warmer than the upper layers, allowing animal and bacterial activity to proceed (which increases carbon dioxide up to 5x more than outside).
To stay alive in cold, life has a few options: Stay above 0C, or drop below 0C.
In terms of staying above 0C, describe staying warm for endotherms.
- Adjust body temperature.
What is the microbial loop in sea ice primary production? How important are bacteria?
- ≈50% of sea ice primary production is in the form of dissolved organic matter (DOM).
- DOM is the main substrate for bacterial growth.
- Microbial loop: Bacteria assimilate DOM into the biogenic particulate fraction that can be utilized by bacterivores, transferring carbon back into the classical food web.
- Bacterial respiration has been estimated at 11% of primary production.
Define: Peat plateaus.
Size?
Flat-topped areas of peat (smaller).
What is a consequence of younger and thinner ice (old ice is melting)?
- more light transmitted through the ice = positive feedback loop of more warming
The Anaktuvuk river fire was the largest fire on record for the tundra biome (2007), where the tundra ecosystem lost >2 kg C/m^2. What is the problem with so much carbon being released?
Overall, the fire released ~2.1 metric tons of C to the atmosphere
• an amount similar to the annual net C sink for the entire Arctic
tundra biome
Carbon balance will subsequently be altered due to
• reduced albedo (absorbs more energy)
• removal of soil organic matter (less insulation)
= Thaws permafrost
What are pingos, and how does permafrost make them form? What are they similar to?
Subsurface water can freeze and force frozen ground upward (pressure) to form cone-shaped mounds with cores of ice.
Similar to palsas, but are much bigger and they grow below the active layer (vs in the active layer).
What is the main cause of ice ages (very brief)?
Changes in thermal energy.
In ice as a biome, who are the algal primary producers and how much of the biomass are they? Does it change from first bloom to melt and late season?
- Pennate diatoms dominate bottom ice algal bloom biomass in the Arctic, can make up >90% biomass in the bottom ice algae community of landfast ice.
- During melt, autotrophic flagellates tend to dominate. Sub-ice communities can also develop in late season (e.g., dominated by the chain-forming centric diatom Melosira arctica
How do warmer summer temperatures affect fish who like cold water (trouts, walleye, Cisco)?
Species are using deeper, colder water in Ontario lake.
Nearshore (littoral coupling) is lower with higher summer temperatures.
Found in deeper waters when littoral zone warmer.
Moose were found to not avoid roads/human activity. They did however, avoid deer. Why?
Brain worm – carried by deer in brain
• Fatal in moose
Larvae passed through blood into feces – then onto snails or slugs Causes sickness in white-tailed deer
Sea ice is one of the largest biomes, and it’s extent equals __-__% of the world’s ocean surface at any one point in time.
Sea ice extent equals 4-6% of the world’s ocean surface at any one point in time.
List 2 ways/methods (general, not subcategories) boreal plants escape frost damage.
- Extracellular (aka intercellular) freezing, which prevents intracellular freezing.
- Supercooling.
Describe this quality of snow cover that affects living organisms: Hardness.
What influences it?
Give an example of an animals it effects?
primarily influenced by wind and thaw; force required to collapse the api.
Affects terrestrial mammals like caribou.
- Reading by Warner *
Canadian peatlands cover about __% of the land surface
Canadian peatlands cover about 13% of the land surface.
- practice exam question *
New data suggests that the ocean heat content is now rising much faster than before. By how much? (%).
50-75%
Canada has the most surface water of any other country, what are these surface waters critically important to?
• All life and the maintenance of biodiversity on the
landscape
• A large range of ecosystem goods and services
(e.g. drinking water, hydro power, agriculture, sanitation, commercial fisheries, recreation), big economic effect too
List the 3 most abundant greenhouse gases, and how long each stays in the atmosphere.
- Water vapour (9 days)
- CO2 (up to 100 years)
- Methane (12 years)
Boreal areas can also be adapted to disturbance, what do larger scale disturbances create, and what animals can live here?
Larger disturbances, over time, create habitat for species that prefer large, uniform forests
• marten, woodland caribou, & great grey owl
Do bigger or smaller animals have a higher mass specific metabolism?
smaller animals.
Why do conifers dominate the taiga? List their 6 main adaptions.
- Short growing season.
- Conical shape, dark colour.
- Low surface area.
- Tolerate nutrient poor soils.
- Accumulator species.
- Mutalism with mycorrhizae.
Describe this principle force acting on sea ice:
- Coriolis Force
causes objects to accelerate because of the rotation of the earth.
• affect processes that occur at the global scale, such as
ocean currents, winds, and ice motion
• in the Northern Hemisphere, causes objects to deflect
to the right
• increases toward the poles – plays an important role in determining sea ice motion
How are fens “fed”? Describe this. What “types” can they be?
Fens are minerotrophic – water supply comes mainly from streams or springs.
Fens can be peatlands & mineral wetlands.
Damage can be caused by _____ which feed & reproduce in the inner bark of trees; causes tree mortality. They essentially girdle the tree.
bark beetles (Scolytidae)
Radiant energy from the sun warms the earth’s atmosphere and surface (water and soil) and becomes heat energy. Describe this mechanism by which energy is transferred through the atmosphere:
- Conduction
- Molecule to molecule (or solid to solid) exchange.
- Depends on the temperature gradient, and rate of transfer varies by substance.
- Air is a poor thermal conductor, while snow is a poor conductor.
When did Canada develop peatlands? Do they span tot he high arctic?
Canada’s extensive peatlands developed since the last glaciation
< 10,000 years ago.
Peatlands are rare in the High Arctic because climatic aridity and harsh growing conditions are not particularly conducive to peatland formation
How does wind speed influence damage? Are damaged trees more susceptible to other problems?
Wind speed largely determines the extent of damage to trees
• Larger trees are more susceptible to windthrow - lever
• stands that have been recently burned
Damage to tree stands increases the probability of pathogen outbreak and tree mortality
Radiant energy from the sun warms the earth’s atmosphere and surface (water and soil) and becomes heat energy. Describe this mechanism by which energy is transferred through the atmosphere:
- Radiation
- Transfer of energy by electromagnetic waves (ie. sun in form of visible light).
- Wavelength is related to vibration frequency: Long - infrared, short - ultraviolet.
- Reading by Warwick *
In terms of the ecological implications of changes in the arctic cryosphere, what effect does the warming arctic cryosphere have on: Permafrost.
- Effect of more water, effect on vegetation and life once it dries up, contaminants.
- Erosion will release a lot of water that will ruin forests and turn them into fens, and can create many lakes and wetlands.
- Southern invasive species.
- Increased vegetation biomass with drier conditions can increase fires.
- Thawing permafrost releases organic matter, gasses, inorganic solutes, and microbiota into the environment.
What is the high arctic in terms of:
- General area (relative to tundra)
- Vegetation, ground, amount of snow
- Winter thaw or no?
- northern tundra
- vegetation is short
- A lot of bare ground
- less snow
- No winter thaw
How do amphipods combat freezing?
To combat freezing ice amphipods conform osmotically to their environment
Animals in the arctic follow the SA/vol rule called the: __/__ power law
3⁄4 power law
Reading by Carlson + Windsor
- How long ago did the last ice age occur?
- How does the melting of glaciers differ for glaciers on land (coastal vs inner) and on the ocean?
- 2.6 mya, ice sheets covered large portions of the northern hemisphere, which melted rapidly in the southernmost land margins, and retreated slower on land. Marine ice sheets had a delayed onset of retreat relative to temperature (retreat followed by rapid collapse).
Define: Biome.
- A major geographical area characterized by a particular type of flora and fauna – primarily determined by CLIMATE.
- A large-scale community of organisms shaped by common environmental conditions (climate and geology)
• usually named after its predominant vegetation association
• general and global, encompassing numerous smaller- scale ecosystems
• e.g., Amazon Basin rainforest vs Congo Basin rainforest
How long ago did this ice age occur?
- 1/5: Huronian
2.4 to 2.1 billion years ago.
Describe this Milankovitch cycle explaining changes in insolation reaching earth:
- Tilt.
- How does it vary, and how long is the cycle?
- Axial obliquity: Ranges from degrees of 22.1 to 24.5 (currently 23.4 and decreasing).
- 41k year cycle.
Define: Supercooling.
lowering the temperature of a liquid or a gas below its potential freezing point, without it becoming a solid
= Ice crystals cannot form at 0°C
What is subsea permafrost, and how did it form?
Under the Arctic ocean, not in Southern hemisphere Formed >11,000 years ago, during the last ice age
• Lower sea level
• Exposed land froze
When ice sheets melted, sea level rose & covered up areas of permafrost
Today, some of seafloor still frozen up to 100m thick under seafloor
Milankovitch cycles explain changes in insolation reaching earth. List the 3 different cycles/changes in orbit.
- Eccentricity.
- Tilt.
- Precession.
Where do peatlands occur and how much of this region do they cover globally?
Peatlands occur mainly in boreal regions, covering 25-30% of the boreal forest region globally
How does the cryospheres influence the world?
Influences global energy balance and ecological functions of northern environments
In terms of formation of snow pack, define: Destructive metamorphism (equi-temperature).
“destruction” of individual grains as snow settles (ie. by wind)
• Decrease in volume
• Increase in density (reduced space between
crystals)
• Occurs early in snow settling
Define: Talik.
Soil or unfrozen ground, year-round, can be above, within or below permafrost
___ can be a major fire season.
Spring.
Boreal forest areas burning is highly episodic with high inter annual variability. Approximately how many million hectares are burnt a year (the range)?
0.2 - 7.6 million ha.
Why do carbon concentrations in the atmosphere oscillate?
They go down a bit in summer due to increased plant photosynthesis.
Main grazers of ice algae include heterotrophic protists (microfauna), metazoans that live within the sea ice (meiofauna), and under-ice metazoans.
Describe the meiofauna of ice. What are the main ones, and how much algal life (and daily ice algae production) do they consume?
- Dominated by flatworms, crustaceans (including harpacticoid and cyclopoid copepods), nematodes, rotifers, and bentho- sympagic larvae
- Consume about 1% of the ice algae standing stock and <6% of daily ice algae production
What is the most widespread peatland in Canada?
a. fen
b. bog
c. muskeg
d. swamp
e. tundra
B - bog
Are we in a new epoch, and headed toward a “hothouse earth”?
- It is possible that we are driving the glacial-interglacial limit cycle toward a hotter state…
- Even if the earth temperature stabilized, it’s still hotter than at any time modern humans have existed.
How long ago did this ice age occur?
- 2/5: Cryogenian
720 - 630 million years ago.
Lightening fires are destructive in the boreal forest. They make up:
–__% of total fires
–represent __% of area burned
Lightening fires are destructive in the boreal forest. They make up:
–35% of total fires
–represent 85% of area burned
Impacts of disturbances are influenced by spatial factors, temporal, and magnitude.
Describe temporal factors (3).
- Frequency - number of events per unit of time
- Duration
- Time of year
Describe how slopes can influence the amount of frozen ground present.
- slope facing towards sun get more sunlight (radiation) – facing south in northern regions
- warmer ground = less likely to freeze (angles of insolation)
- steep slopes do not get as much direct sunlight = relatively colder, also don’t hold as much snow
Animals may experience severe range contractions and possible extinction due to environmental change… what 2 things can occur due to this? (Ie. genetically).
- Isolation.
- Genetic drift.
In North America, what kind of forests would you find north?
Tundra.
Describe this principle force acting on sea ice:
- Wind
What does it cause/how?
primary force responsible for ice motion • Short-term ice motion – days to weeks • causes the ice to drift – drag force • force depends on the speed of the wind and the characteristics of the sea ice surface • rough ice surface is affected more • Speed is predictable - sea ice that drifts freely moves at 2% of the wind speed
Where would a jack pine be found (habitat)? Is it common in MB?
Jack pine (Pinus banksiana): continental, found on dry, sandy outwash plains and former dune areas – low nutrient, droughty substrates not tolerated by spruce and fir. • most common pine in Manitoba
Do boreal ecosystems experience natural disturbances often? What are 4 major ones?
Boreal ecosystems are regularly subjected to
large-scale natural disturbances - they’re disturbance-based ecosystems:
Major disturbances:
1) Fire
2) Insect infestations
3) Disease
4) Severe weather
Boreal forest ecosystems are constantly changing Most boreal vegetation and wildlife species have adapted to, and depend on, disturbance.
Define: Discontinuous permafrost.
How thick is it?
Discontinuous→ occurs under 50-90% of land in a defined area
• Up to 10 m thick
What is the intermediate disturbance hypothesis?
- Highest diversity is often maintained at an intermediate level of disturbance.
- Both frequency and scale of disturbance affect diversity
How does dried peat have some uses for humans?
Dried peat is a traditional fuel in places where it is of high quality and easily accessible (e.g., Ireland).
- Also in alchohol!
Fire size in the boreal forest varies:
• Most fires are small (___% are ___ ha
these together represent 97% of area burned
Fire size in the boreal forest varies:
• Most fires are small (70% are <5 ha)
• only 3% of fires are >200 ha
these together represent 97% of area burned
__% of land (globally) has permafrost underneath. Over __% of Canada does.
24% of land (globally) has permafrost underneath. Over 50% of Canada does.
Why is it colder at the poles of the earth (3 main reasons)?
- When sunlight hits the ground obliquely (at an angle), there’s more surface area to cover and less absorption, so less amount of energy per unit area.
- The sun’s rays have to travel farther through the atmosphere at higher latitudes, resulting in less heat reaching the ground, less absorbed into the ground, and more reflected into the atmosphere.
- Long nights in winter (months sometimes), more heat is lost to the atmosphere than gained at the surface.
What 3 things can animals do if the environmental conditions change outside their tolerance?
- Move (new location).
- Adapt (adapt to new conditions in original habitat).
- Go extinct.
T or F: fires can cause a big decrease in forest soil depth.
True
Why can’t trees grow in the far north?
The lack of summer warmth – not cold winters.
• Photochemical reactions (photosynthesis) can
only happen if plant tissues are warm enough
• Results in low growth (leaves and roots are a necessity, wood/growth is a luxury).
What is Clements’ idea of a “superorganism”?
- Communities are “superorganisms”)
- Demonstrates that communities change over time in very discrete ways (like human development) ultimately resulting in a predictable endpoint
Does any flora or fauna live on glaciers and ice sheets?
- Microbes can live on the ice surface or in solid ice.
Microbe – any living organism that spends its life at a size too tiny to be seen with the naked eye.
‒ includes bacteria and archaebacteria, protists, some fungi and even some very tiny animals
What’s the difference between a homeotherm and endotherm?
Homeotherm: animal that maintains an approximately constant body temperature.
Endotherm: generates heat to maintain its body temperature. They rely primarily on their own energy reserves to produce heat in cold conditions.
List a few things that can influence albedos.
Snow depth, age, vegetation, sunlight, cloud cover. Pollution (adds more cloud nuclei and changes reflection/absorption - thicker = more absorptive).
Main grazers of ice algae include heterotrophic protists (microfauna), metazoans that live within the sea ice (meiofauna), and under-ice metazoans.
Describe the under ice metazoans. What are the main ones, and how much algal life (and daily ice algae production) do they consume?
- Dominated by gammarid ice amphipods and planktonic calanoid copepods
- Amphipod grazing rates estimated at 1-3% of ice algae
- Calanoid copepods observed to graze on ice bottom, but no direct estimates to date
- > 65% sloughed ice algae floats or sinks slowly through the water column where it is primarily grazed by copepods
- Gelatinous zooplankton are commonly observed feeding along the sub-ice environment
- Arctic cod is a keystone species, providing a central link between grazers and higher trophic level fish, birds, and marine mammals
What are 7 things that can influence the amount of frozen ground?
- Soil type
- Lakes and rivers
- Snow
- Slopes
- Wind direction
- Plants
- Peat
How can plants accomplish extracellular freezing?
- “Antifreeze” accumulates inside cell walls (sap and other compounds)
- Ice crystals form in between cells in intercellular spaces
Is there a correlation between amount of peatland on a landscape and fire events? What else correlates to more fire events (relating to peatland)?
- Yes!
- Drought.
- Reading by Warwick *
In terms of the ecological implications of changes in the arctic cryosphere, what effect does the warming arctic cryosphere have on: Lake and river ice.
- Increases in certain organisms, contaminants, invasive species.
- Less wind-induced mixing + more light for photosynthesis, will cause increases in zooplankton and contaminant transfer to high trophic levels.
- Shifts habitat of cold adapted species.
- Increases in mercury and other contaminants in fish.
- Southern plants and fish can invade.
How does the albedo in lake vs sea ice differ? What does this have to do with their type of growth?
- Albedo is much higher in sea ice due to the numerous impurities found in sea ice (lamellar growth) compared to lake ice (planar growth).
- 99.9% of impurities are expelled from accreting lake ice
- 10 to 40% impurities are trapped within sea ice
What type of forest fires usually born most intensely and spread fastest?
Ground fires.
List 5 things that cause the formation of layers in snow.
- Wind→ increase wind, increase convection (primary driver)
- Water Vapor→ vapor gradient between snow and air
- Radiation→ Shortwave and longwave
- Advected Heat (Rain)
- Soil contact→ convection
Define: Climate.
- Average state of Earth’s surface conditions.
In terms of sea ice, define: Pack ice.
almost constantly in motion, farther from shore, drifts in response to winds, currents, etc
What is a problem with arctic warming in terms of light reflection (albedo)?
The Arctic is warming twice as fast as the rest of the planet
• changing from a highly reflective surface to a very
dark surface
• Sunlight that would normally be reflected back into
space (by sea ice, snow or glaciers) is instead being absorbed by dark surfaces (ocean, land & rock)
What’s the most recent glaciation in North America?
Wisconsinan glaciation.
When Lake Agassiz was able to drain into Hudson’s bay, and the depressions left filled with marine water, this became the ______ ______.
Tyrrell Sea.
Fresh water is most dense at…
a. 0C
b. 2C
c. 4C
d. 6C
e. 8C
c - 4 degrees.
Describe how plants can influence the amount of frozen ground present.
• Keep soil cooler in summer – leaves can block
sunlight from reaching the ground
• especially evergreen trees
• create bare ground at their base – loses heat easily
• block sun in winter – more likely for frozen ground
One way to reduce heat loss is to get bigger. Describe Bergmann’s rule.
Animals of larger size are found in colder environments.
Less SA/vol ratio, less heat loss.
What happens to species that were around before the last glaciation?
Their range likely expanded and contracted over time.
Low temperatures cause rigidity of membrane phospholipid bi- layers resulting in a loss of ion permeability. Production of ______ fatty acids (e.g., ___-__) play a particularly important role to avoid this increase in viscosity.
Low temperatures cause rigidity of membrane phospholipid bi- layers resulting in a loss of ion permeability. Production of polyunsaturated fatty acids (e.g., omega-3) play a particularly important role to avoid this increase in viscosity.
What will happen to the tree line as the arctic warms?
- Trees move north
- Temperature-induced drought
- Animals will follow!
How do insect outbreaks affect fire risk?
e.g. spruce budworm; Siberian silkworm
- Early summer drought enhances the insect population.
- Forest structure (suitable host trees) enhance insect population further.
- Insect population reduces forest biomass
- Forest structure (ex. dead trees) and biomass enhances fire hazard.
- Fire hazards reduce forest structure and biomass.
- Climate enhances fire hazard - it’s a cycle!
__% of the land in the Northern Hemisphere freezes seasonally.
• ~__ million square kilometers
58% of the land in the Northern Hemisphere freezes seasonally.
• ~55 million square kilometers
How can global warming change the carbon balance in the tundra?
Warming may change the carbon balance on the tundra – from a carbon sink to a carbon source
- More carbon will be released due to decomposing microbes that release carbons, that won’t be offset by increased plant growth.
What is ecological succession?
- Communities change through time.
* Succession is the replacement of one community by another.
Why are boreal forests so susceptible to large- scale insect disturbance? 2 main reasons.
1 Relatively lower species diversity = less predators
2. Relatively lower productivity
Describe Maritime snow in terms of:
- General description
- Snow depth
- Layers of snow
Warm, wet, many melt features (ice etc..)
- Snow depth: 75-500 cm
- Layers of snow: >15
What kind of tree is a tamarack, and where would it be found?
- Deciduous conifer that lives on thin, waterlogged substrate in level areas with permafrost.
- Adapted to avoid water stress in spring.
What 2 things determine snow crystal shapes?
- Humidity
2. Temperature
There are 3 ways the sun’s energy can be reflected and absorbed, list the 3 (and relative proportion of each).
- Absorbed in the atmosphere (23%).
- Absorbed at the surface (48%).
- Reflected (29%).
Boreal forests are exceptionally unstable in vegetation. What’s most important cause of disturbance in boreal ecosystems?
Fire.
Define: Polynyas
- Persistent (and predictable) open water surrounded by ice
- sustained by winds or ocean heat
- often occur near coasts, fast ice, or ice shelves
- One of the major lifelines to Arctic ecosystem structure and function
How would an organism (ie. human) react to…
- is below LCT
- in TNZ
- above UCZ
- is below LCT: shivering
- in TNZ: changes in blood flow (dnm?)
- above UCZ: sweat
Are forests on the coasts more or less likely to burn? What other disturbances are also common here?
Forests on the coast are less likely to burn
But other impacts: wind & coastal erosion resulting in death of conifers
Are current CO2 concentrations very different from historic levels? Does it vary?
Over the past 20 million years, the Earth’s climate has oscillated between relatively warm and relatively cold conditions:
•During interglacial periods, atmospheric CO2 concentrations were relatively high
•during glacial periods, CO2 concentrations were relatively low.
We are currently in an interglacial warm period
To stay alive in cold, life has a few options: Stay above 0C, or drop below 0C.
In terms of staying above 0C, describe staying warm for ectotherms. Many possible options revolving around a common theme!
Ectotherms don’t produce their own heat, so must reduce heat loss (by habitat selection, move where it’s warmer).
- Can move underground.
- Communal nesting/huddling.
- Alternative life stage (in many inverts, overwinter in egg stage, ie. mosquitos).
- Move into deeper water.
- Move under snow (subnivian layer)
Generally,
Ectotherm = _____
e.g., most insects, fish, herps
Endotherm = _____
e.g., most birds & mammals
Generally,
Ectotherm = Poikilotherm
e.g., most insects, fish, herps
Endotherm = Homeotherm e.g., most birds & mammals
What triggers insect population increases and associated widespread tree mortality? 2 reasons (causing 2 thing).
- sustained periods of abnormally warm weather
- drought
–> Both are correlated and create dry conditions. Multiple years of this can have a synergistic effect (much more damage than just 1 year).
- practice exam question *
New data suggests that the ocean heat content is now rising much faster than before. By how much?
A. 10% B. 50-75% C. 100% D. 150% E. No change.
B
_____’s _____ forest is the largest remaining intact forest.
Canada’s boreal forest is the largest remaining intact forest.
Describe Tundra snow in terms of:
- General description
- Snow depth
- Layers of snow
Thin, windblown, no trees, few melt effects
- Snow depth: 10-75 cm
- Layers of snow: 1-6
What was the largest fire on record for the tundra biome (2007)?
Anaktuvuk River fire in 2007
• burned > 1,000 km2
• largest fire on record for the tundra biome
Describe how a pitcher plant in a sphagnum bog can still collect nutrients.
- Their red colour attracts flies and other meat-eating insects, they have hairs inside covered with a slippery gel.
- The insects fall into the watery solution and are trapped and drown.
- Plant secretes digestive enzymes into this warm, sun-heated solution; OR bacteria, microbes, and mosquito larva digest & the plant gets the waste products.
What is the definition of Boreal Ecology (very brief)?
Ecology of the north.
Describe this layer of a nivean environment, and give an example of an animal that may live here.
- Intranivean
within the snow
• Area where some animals burrow, e.g. ruffed grouse
T or F: Canada is home to the world’s largest lakes and rivers.
True!
Main grazers of ice algae include heterotrophic protists (microfauna), metazoans that live within the sea ice (meiofauna), and under-ice metazoans.
Describe the microfauna of ice. What is the main one, and how much carbon is it consuming?
- Consume ≈1% of total particulate carbon during an ice algae bloom and do not seem to consume diatoms (Michel et al. 2002)
- Mainly bacterivores
