Wetlands, Peat, and Tundra Part 2 Flashcards
What are the major landscape building features in northern systems?
glaciation and de-glaciation (above ground)
permafrost and melting permafrost (below ground)
__% of earth’s surface used to be covered by ice sheets, today only __% is covered
30
11
Pleistocene glaciation was ___-___ yrs ago, and was the southern extent of the ice sheet in north america
What were the 2 ice sheets associated with it?
1million to 18,000 yrs ago
Laurentide Ice sheet- eastern North america
Cordilleran ice sheet- western north america
*between them= rockies
The _____ glaciation covered most of the northern half of north america 85,000-___yrs ago
Wisconsin glaciation
7000
= northern systems are still relatively young
Ice is heavy, so ___ the crust of the earth. When the ice melts, the earth __ resulting in lots of changes
compresses
lifts
T/F
The cypress hills were not glaciated by the laurentide ice sheet
true
not glaciated at all= lots of species could survive
What are some of the consequences of the distribution of the proglacial drainage and the proglacial lakes?
- glacier melts= more water –> impacts fish etc
- permitted fish etc to migrate northwards across present-day drainage divides
- dispersal of some tree species into the deglaciated areas
Glaciation stripped away ___, deposited glacial ___, and created many ___ basins and ____
soil
till/ drift
lake
riverbeds
Glaciers began to recede ~___years ago and forest cover gradually regenerated over Canada
20,000
The boreal forest took on its present character ~___yrs ago making it a ___ ecosystem
5000
young
What are 4 signs of glaciation left on the landscape (evidence)?
- glacial fluting
- glacial moraines
- raised beaches- isostatic rebound
- eskers (water moves under the glacier, carrying sill)
Periglacial= ___of a glacier
edge
Permafrost=
earth material (soil, bedrock, clay, etc) that’s been below 0C for >2yrs, so it has become ice-cemented
Permsfrost can be ___-___ deep, with a much shallower ___ ___ that melts seasonally
200m-1km
active layer
T/F
1. frozen land below glaciers is permafrost
2. Many trees are adapted to live in permafrost
- true
- false
- not many can live here; nowhere for the roots to go
Continuous vs discontinuous zone of permafrost:
Continuous zone= permafrost is found everywhere
Discontinuous zone= permafrost is spatially sporadic
Mean annual air temp:
- < -6.7C= permafrost is ____
- -3.9C to -6.7C= permafrost is ____
- -1.1C to -3.9C= permafrost is restricted to ___
- -1.1C= southern ___ of permafrost
continuous
discontinuous
peatlands (easier to have permafrost in peatlands b/c more insulated)
limit
What is a talik? How does it form?
= unfrozen land surrounded by frozen land
Happens b/c:
- human modification
- change in water flow
- land below water = warmer b/c of water’s heat capacity
- vegetation on surface is insulating
Give 3 reasons why peatlands are so prevalent in the north
- permafrost restricts movement of water
- flat terrain can reduce water flow
- short summers and cold temps reduce rates of decomp
3 conditions for peatland to form:
- annual precipitation must be greater than 500mm b/c soils need to become waterlogged
- annual biotemp cannot be too warm
- there must be a positive water balance in the area (sufficient water)
Melted water in permafrost areas can’t percolate through ice= ___ ___ develop and change ___ and the ___ below them
shallow lakes
communities
permafrost
cold soil temps found in some boreal forests result in:
- reduced organic matter ____
- restricted nutrient ____
decomp
cycling
Bogs have low____ and their only source of water is through _____. They’re pH is ____
nutrients (ie fertility)
precipitation
acidic
t/f
bogs impact the water table
true
Bogs may be treed with ___ ___ or may be treeless. They’re usually covered with poorly decomposed ____
black spruce
sphagnum
How do bogs form?
Paludification= the conversion of dry land to a peatland
- results from altered drainage (beaver dam) or by an elevation of the water table
What role to sphagnum play in plaudification?
they colonize the edges of a water body and draw water towards them = water expands outwards
sphagnum move inwards until they’ve terrestrialized the whole body of water, and peat forms underneath
Peatlands are hostile places for plants because they’re waterlogged, have low ___ and ___ availability, and are high in ____
What kind of plants can thrive in these conditions?
nutrient and oxygen
toxins
acidophiles= thrive under acidic conditions
What are the 4 types of bogs?
- basin
- domed
- palsa (like small pingos)
- peat plateau
Explain how a basin bog forms
- open water lake is present
- over time, sediments accumulate on the bottom (making it shallower) and there’s an increase in floating and submerged plants
- these fill in the lake, leaving you with grasses/ shrubs on the ‘shores’ of the former lake, and a swampy center
Spruce bogs are bordered with ___ ___ and ___, and will likely become a ___ bog with time
black spruce
tamarack
basin bog
What is a domed bog?
raised bog!
bogs fill area but peat continues to develop, so it lifts and spreads beyond original area
What’s a palsa bog?
a mound of peat that develops as a result of the formation of ice beneath the surface
- also raised
- like a pingo but smaller
*ice in center
A fen is a peatland that’s influenced by ___ from outside its own limits
water
- water is moving= higher nutrient load
Fens are connected to ____ and may connect areas as areas fill with water (___)
groundwater
plaudification
Poor fens are slightly ___
Rich fens are ____
and extremely rich fens are ___
acidic
neutral
alkaline
