Polar Landscapes

A Regional Approach

All elements of physical geography integrated in the ecoregion approach of Robert Bailey, UCLA Geographer, U.S. Forest Service

General circulation perspective

• Intertropical Convergence Zone (ITCZ) – brings summer rains in equatorial &

tropical latitudes

Subtropical High – brings drought, annually or seasonally

Polar Front – brings precipitation in the midlatitudes

Polar Easterlies – the cold landscapes of tundra and ice caps

Organized by basic climate processes controlling precipitation and temperature

Organization

• 1st – climate• 2nd – soils • 3rd – landforms• & hydrology• 4th – biogeography• with discussion of geology because geology plays an

important role in deserts in defining meso-scale landform regions

Polar Climates

Dominated by Polar HighDense, cold air flows equatorward

Extreme Seasonal Changes

24 hr days in summer, 24 hr night in winter

Ice Cap Climate

Mean monthly

below zero

Ice Cap Climate

•Dominated by dry, frigid air masses

•Average temperature below freezing most or all year

•World’s coldest surface air is found in Antarctica in S. hemisphere winter

•Glaciers accumulate snow and ice despite low precipitation (<80mm/yr in Antarctica)

•Precipitation exceeds small evapotranspiration demand

Examples: Antarctica, North Pole, Greenland

Tundra Climate •harsh winters •low average temperatures •little snow or rainfall•too short summer season for trees.

•Influenced by permafrost, a layer of permanently frozen subsoil in the ground. The surface soil, which tends to be rocky, thaws in summer to varying depths.

•The combination of frozen ground and flat terrain impedes drainage of water. Held at the surface or soaking the upper layer of soil, the water forms ponds and bogs in low areas

Soils

Poorly DevelopedIn Rocky Areas

SoilsExperience overturning from permafrost activity

Soils: Position is very important

Upland soils: entisols

Poorly developed

Lowland soils: histosols

Peat – plant accumulation

In low-lying areas where water collects from permafrost melting, get accumulation of organic remains of plants called PEAT.

Name for soils: histosol

Why does peat accumulate ?

•Production by plants exceeds decomposition

•Abundant growth due to available moisture during growing season

•Preservation of plants (cool conditions)

•Saturated conditions - slow, anaerobic decomposition by methanogenic bacteria

•When plants decay (with drying & warming), release of methane

Landforms &

HydrologyPermafrost

Ice Wedge Polygons

Pingo

Patterned Ground

Solifluction

Rocky Uplands

Rivers

Permafrost Permanently frozen water in the ground

Underground mine in permafrost (Yakutsk, Permafrost Institute, Dr. P. Konstantinov

When thaws, creates “thermokarst”Pipelines Break

Roads Cave In

Buildings Collapse if not properly insulated

Natural permafrost

cycle

Northwest Territories

Northwest Territories

Pingo

Northwest Territories

Pingo

Can grow as water moves to ice core

Patterned Ground – Rocky & Flatactive layer “churning” sorts rocks

Northwest Territories

Solifluction: sloped ground in finer materials flows (oozes)

Kinnard Research, Excavation, Yukon

TopographicPosition

Rocky uplands

patterned ground

Low slopes

solifluction lobes

Lowlands

ice wedge polygons

Rocky Uplands

Felsenmeer – rock block field broken up by frost weathering

Steep slopes with lots of frost-weathered rock: Rock Glaciers

Ice core & seasonal freeze/thaw moves rocks

Rivers

Winter – frozen

Spring – thaw

Summer – very

aggressive

erosion

SuddenThaw

FloodsLena River

Siberia

Breakup Timing

http://aprfc.arh.noaa.gov/rwpindex.php

River Ice

• River ice is a unique aspect of Arctic Hydrology. All rivers experience some ice effect, yet in some instances, runoff events associated with river ice have produced extreme and dangerous flooding events. River Ice interacts and obstructs the passing of floods. The blockage causes water levels far higher than those experienced for the same flows under open water conditions.

YUKON RIV HARD LIFTED AND SHIFTED SHEETS

Shifted ice – large ice sheets that have moved short distances from their original locations as rising water levels create wider areas of open water into which the ice can move

http://aprfc.arh.noaa.gov/rwpindex.php

TYPICAL RUN OF ICE

May be 10-20 miles in length

Reach of large moving sheets (nr breakup front)

Reach of mixed sheets, pans, and chunksReach of mostly chunksSubsequent runs are mainly chunks

http://aprfc.arh.noaa.gov/rwpindex.php

YUKON RIVER

Ice run – a continuous length of moving ice

http://aprfc.arh.noaa.gov/rwpindex.php

NULATO RIVER ICE JAM

Ice jam – an ice run that has stopped moving due to any of a variety of reasons; this very small jam has broken sheet ice holding back a small run of chunk ice

http://aprfc.arh.noaa.gov/rwpindex.php

ICE JAM IMPACTS

Upstream from the jam...

Fast water level risePacked ice chunksPotential flooding

http://aprfc.arh.noaa.gov/rwpindex.php

Flooding impact

Water outside the channel

http://aprfc.arh.noaa.gov/rwpindex.php

KUSKO RIV ANI VILLAGE FLOODING

Village flood – water spreading into a village that covers roads or threatens buildings

http://aprfc.arh.noaa.gov/rwpindex.php

Lena River Delta

Yukon R. Delta

Biogeography

Cold & Dry

Source: Solomon, 2000

Effect of Latitudeor Altitude

-severe winters

-short growing season,cool summer; too littlewarmth for tree growth

-arctic or alpine

Tundra

Small growing season

Dwarf Willow

Dwarf Birch

Generates dwarf forms adapted to survive in

Cold and Windy winters

• The arctic tundra lies between the Boreal Forest and the permanently frozen polar regions– It is a treeless

biome characterized by extreme cold, wind, and permafrost

– Permafrost is continuously frozen subsoil

Long, bitter-cold winters characterize the tundra

SNOW AND MICROCLIMATE

The snow on top helps protect the tundra plants underneath from the worst of the cold above. When it is very cold outside, take a

thermometer and measure the temperature underneath the snow, and you will see that it is quite a bit warmer! This helps not only the

tundra, but small rodents such as the red-backed vole.

Light and heat may not be the only limiting factors for plant growth•Days are long and temperatures may reach the teens in summer

Wind and moisture deficit are also important•Thin, active layer holds limited moisture. Small, leathery leaves, closely spaced to protect stomata•Hairs limit air circulation•Flowers are small•Plants often occur in tufts for protection•Prostrate growth - stems spread out over ground with little vertical growth - especially willow

Arctic tundra

Lichens Common

Fungal layer

Fungal layer

Algal layer

• Mutualism: Relationships between fungi and hosts that are mutually beneficial

• Symbiosis: intimate association between two distantly, related species that are mutually benefiting from this association

• Food for Caribou

Adaptations to Light Conditions -Perennials

Tundra Flowers

These plants come back every year. Short flowering & reproductive season

Low Arctic Tundra

•Extends north from treeline along a line from Northern Alaska to northern Quebec and southern Baffin Island (10 degree C isotherm)•Cold, with low precipitation•Nearly the entire area is underlain with permafrost

•Almost complete vegetation coverage (except unfavourable areas)•Dominated by dwarf shrubs (birch and willow)

•Vegetation traps snow and provides shading from summer heating

•Peat accumulation at poorly-drained sites•Any black spruce is very stunted and abraded by snow

•Major summer range and calving grounds of some of Canada's largest caribou herds

Mid Arctic Tundra

•Transitional band between high and low arctic•Plant cover more than 50% in most areas but bare ground still exists locally•Vascular plants more common than in high arctic - willow common

Cumberland Sound, Baffin Island, Nunavut, Canada

Wetland Environments

•Cover 14 to 18% of Canada•Mainly just to the south of treeline in discontinuous and sporadic permafrost•Pockets further north•Major carbon sink

•Potential future source of greenhouse gases (methane)

•Hydrophyllic vegetation present due to water table at or above mineral soil

Example of Plants

Sedge

Willow-herb

Cotton grass has seeds that are dispersed across the tundra by the wind.

Source: Natural Resources Canadahttp://atlas.gc.ca/english/facts/wetlands/wetlands_ewetdist2_e.html

Animals of the Tundra – Color Adaptations

Arctic Hare

Arctic Fox

Lemming

These animals turn white in order to camouflage themselves from predator or prey

Animals of the Tundra – Cold Adaptations

Polar bears shelter in dens in winter and to have cubs

Arctic ground squirrels hibernate

Animals of the Tundra

Muskox dig through snow in winter for food, if snow is frozen solid, they could die

Caribou migrate south during winter in search of food

Birds of the TundraSnow geese migrating north in summer

Tundra birds help to distribute seeds. When they eat bright colored berries, they fly to other areas and leave the seeds to grow.

The Arctic Fox eats birds and rodents.

                               

Caribou eat lichen.

The Musk ox eat lichen, moss, grass, and leaves.

Lemming eats grass & other vegetation.

The Polar bear eats large & small mammals, birds, fish, berries, and leaves.

Food Sources

Hansen, Scientific American, March 2004

Arctic Warming at the Front Line of Global Change

Dramatic changes in Artic Sea Ice

1979-2003: Progressive Loss of Arctic Ice

Imagine an ice-free Arctic

Source:

Corell, R. W., 2004: Impacts of a warming Arctic. Arctic Climate Impact Assessment (www.acia.uaf.edu) Cambridge University Press (www.cambridge.org).

The increase in growing season length over the last 50 years averaged for eight stations in Alaska having the longest and most consistent temperature records.

The increase in growing season length over the last 50 years averaged for eight stations in Alaska having the longest and most consistent temperature records.

Gradual Loss of Tundra (purple) as growing season lengthens