Wetlands, Peat, and Tundra Part 3
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Oligotrophic= ___ fertility Mesotrophic= ___ fertility Eutrophic= ___ fertility
low medium high
fens have a ___ pH, bogs have a ___ pH (ie ___)
high low (acidic)
Wetland formation is a function of: 1 2 3 4 5
• climate • geomorphology (landform and soil parent material) • hydrology (internal/external drainage) • chemistry of water/ soils • biology (fauna and flora)
t/f swamps must be wet all year long
false swamps are forested wetlands, so they may not be wet all year long because trees need dry-ish conditions to grow
swamps are ___ wetlands/ peatlands, associated with lakes and ____, and periodically inundated by ____
forested waterways water
Why are marshes and swamps usually found further south than peatlands?
because decomp is temp dependent - marshes/ swamps are on well decomposed mineral soil
Marshes are adjacent to ____, so they have shallow water whose levels ____
waterways fluctuate
Which type of wetland is described: - little accumulation of peat - high productivity - high decomp - herbaceous vegetation
marshes
t/f marshes can be coastal (marine) or freshwater
true
Graphs of land and ocean temp departures from average tell us that ___ systems are getting especially warmer
northern
Mean annual air temp (MAAT) is determined solely by ____ ____, and mean annual ground temp (MAGT) is key to controlling ___ thickness MAAT ___ MAGT
prevailing climate permafrost impacts
Is the ground below the permafrost (very deep) impacted by global warming?
no geothermal heating causes the ground below permafrost to be >0 degrees C (always unfrozen, not impacted by global warming)
typically, the further north you go, the ___ the active layer becomes Also, permafrost becomes more ___
thinner continuous
___ have a shallow active layer due to the insulating properties of peat, which dries in summer
bogs
fens are wet, which ___ the depth of the summer thaw (___ active layer)
enhance deeper
sandy areas (eg beach ridges)= the ground can easily ___ in summer, resulting in a ___ active layer
warm deep
Tundra polygons are caused by the earth ___ with __-__ cycles
cracking freeze-thaw
How do ice wedges form?
frozen winter ground cracks, and fills with water in spring - water pushes soil up, and when it freezes, expands the crack more - more water enters the expanded crack, freezes, expands, ….
In a high-centered ice-wedge polygon, the ice wedges have ____ because the water flows ___
disappeared downhill
In a low-centered ice-wedge polygon, ice-wedges are ___/___ because water is flowing ___ them
forming/ present into
What causes a ‘drunken forest’?
as permafrost melts, trees slump into bogs etc because they’re no longer supported by the permafrost underneath
_____ ____= a shallow body of freshwater that’s formed in a depression by meltwater from thawing permafrost - why does the depression form?
thermokarst lake • depression often produced by collapse of ground levels associated with permafrost thaw
ebullition=
bubbling of methane in a thermokarst lake from decomposition
How does ebullition occur?
permafrost thaws - trees fall into thermokarst lake b/c land slumps - organic matter (trees) decompose at the bottom of the lake - methane bubbles form from this decomp, and bubble up to the surface