Tundra Biome

Arctic tundra and alpine (high elevation) tundra

N-hemi= fringe of arctic ocean
S-hemi= southern South America, fringe of Antarctica
high elevations, above altitudinal treeline

Temperature: summer: short season, w/ long days, t>0 (24hrs daylight)
winters: long avg. T<<0 (long periods of darkness)
high annual range; low daily range
ppt: low= "arctic desert"
summer (wetter), winter snow + wind
humidity:
-both ppt + evaporation=low=relative humidity is high
water balance:
primarily E limited = Low PE
-small H2O deficit in summer

See graph

Permafrost: ground permanently frozen
- true arctic defined by this
-sub= patches of frozen
Active layer: surface that thaws in summer
-usable for plants + substrates

-permafrost prevents H2O from percolating into soil + flat landscape + surface runoff= lots of standing H2O
this is why tundra is humid even though there is little ppt

Barren land
life forms= bryophytes, herbs and shrubs
limited by:
-cold temperatures
-short growing season
-cant get deep roots b/c permafrost

Will grow shallow roots
dwarf growth form: due to wind + ice will grow smaller
drought resistance: soil H2O frozen
-have to be accustomed to little water
99% perennial: growing season too short for annuals
-quickly rebuild regenerative sources
abundant root vs shoot biomass:storage organs are below ground and there are more
for ex) the arctic heather will put new green material where plant left off

Freeze-thaw action of soil
-results in variable moisture conditions in space and time
-frost heaving
-sorts-soil particles by size

Low annual insolation and intensity is low
extreme seasonality
high reflection
H2O takes energy to melt

A human impact: H2O expands + forces soil up
-when volume decreases soil creates pattern ground
hummocky topography, where irregular pits and depressions develop

Driving which deepens the active layer causing melting of soil which decrease volume of soil, results in depressions which fill with water, melts more, subsides more mechanical disturbance.
resource extraction

consequences: variable moisture conditions in space + time (flooding, inundations, + drought)

1 darker land: absorbs more slaor E
2 more of the xtra trapped E goes diectly into warming rather than into evap
3 the atmosphere layer that has to warm in order to war the surface is shallower in the arctic
4 as sea ice retreats solar heat absorbed by the oceans is easily transferred to atmosphere
5 alterations in atmosphere and oceanic circulation can increase warming
-equatorial water moves to moles

Decrease sea ice and snow
vegetation will increase because more sun.