Polar ecosystems
description
Transcript of Polar ecosystems
![Page 1: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/1.jpg)
Polar ecosystems Arctic/Antarctic contrasts Tundra - the physical template
(climate, landforms, soils) Tundra plant and animal communities Winter survival Population cycles Management issues Responses to future climate change
![Page 2: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/2.jpg)
Arctic(a) vs. Antarctica
land: 8 X 106 km2 (30% ice)
substantial terrestrial food
land mammals
herbivorous & insectivorous birds
land: 14 X 106 km2 (97% ice)
no terrestrial food
no land mammals
no herbivorous or insectivorous birds
![Page 3: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/3.jpg)
Arctic(a) vs. Antarctica not
geographically isolated
glacial refuges ice-free coastal
zone in summer relatively high
plant and animal diversity
geographically isolated
no? glacial refuges
v. restricted ice-free coastal zone in summer
low plant and animal diversity
![Page 4: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/4.jpg)
Tundra ecosystems
“tundra” = treeless barrens
![Page 5: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/5.jpg)
Global distribution of tundra
![Page 6: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/6.jpg)
Arctic ecosystems in Canada
N.Arctic = polar desert
S.Arctic = tundra
![Page 7: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/7.jpg)
Tundra ecosystems
Tundra ecosystems are associated with areas of extreme near-polar climate which operates either directly, or through a series of environmental forcings (primarily thaw-layer dynamics) to limit productivity and biodiversity.
![Page 8: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/8.jpg)
Tundra ecosystems
Low species diversity may promote instability. This is expressed by highly cyclic behaviour.
Arctic communities are geologically-recent developments in the planetary biome landscape.
![Page 9: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/9.jpg)
Day-length and insolationat top of atmosphere
Equator
40°N
60°N
90°N
Inso
lati
on
(w m
-2)
0
100
200
300
400
500
600
daylength (North Pole) 0h 12h 24h 12h 0h
J M J S D
![Page 10: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/10.jpg)
Tundra climate stations
Barrow
Churchill
IqaluitSvalbard
Tiksi
Gulf Stream
Treeline
60°N
75°N
![Page 11: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/11.jpg)
Mean monthly temperatures,tundra climate stations
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
J F M A M J J A S O N D
Barrow,AK
Churchill
Iqaluit
Svalbard
Tiksi
![Page 12: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/12.jpg)
Mean monthly precipitationtundra climate stations
J F M A M J J A S O ND
Barrow,AK
Tiksi
ChurchillIqaluit
Svalbard0
10
20
30
40
50
60
70
Barrow,AK
Tiksi
Churchill
Iqaluit
Svalbard
![Page 13: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/13.jpg)
Synoptic climatology(after Reid Bryson)
Treeline
Mean position of Polar Front (July)
ARCTIC airmass
Bering Sea ice
![Page 14: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/14.jpg)
Frost-free days
Treeline
![Page 15: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/15.jpg)
Mean annual snowfall (mm)
Treeline
![Page 16: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/16.jpg)
Permafrost distribution(note transect lines
and presence of sub-sea
permafrost)
![Page 17: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/17.jpg)
Alaska
Siberia
![Page 18: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/18.jpg)
Boreal forest Tundra
Permafrost
patchy discontinuous continuous
120 30 mean #d >10°C
mean locationPolar FrontJulyJan
150 240 mean #d <0°C
treegrowth
pollen/seedviability
150 60 frost-free days
![Page 19: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/19.jpg)
The critical thaw period
Data from Barrow, AK
~70 d
~40 d
![Page 20: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/20.jpg)
Microclimatology: slope and aspect
Aspect Flat South-facing North-facingSlope (°)Ground-Sunangle (°)0 10 20 40 10 20 4045 55 65 85 35 25 5210Direct-beam radiation, solar noon, summer solstice, 68.5°N
forest?
![Page 21: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/21.jpg)
Vigorous tree growth on south-facing slopes near
treeline
![Page 22: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/22.jpg)
Polar montane environments:
freeze-thaw weathering -
felsenmeer and talus cones
![Page 23: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/23.jpg)
Polar uplands:
thaw-layer dynamics
and solifluction
![Page 24: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/24.jpg)
Polar lowlands
![Page 25: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/25.jpg)
Cryoturbation and patterned ground
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
dwarf shrubs,grasses
sedges,lichens
![Page 26: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/26.jpg)
Frost polygons: note unvegetated ‘boils’ and standing water in cracks
![Page 27: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/27.jpg)
Tundra floras(product of late Tertiary cooling and landbridges during glacial phases?
Centre-of-origin?
Davis Strait “gap”(major floristic contrast)
Plio-Pleistocene
migration
Plio-Pleistocene
migration
Alpine highlandsof NE Asia
![Page 28: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/28.jpg)
Topography Tundratype
Flora Thawdepth(m)
Organiclayer (m)
rocky, well-drainedridges
Heath evergreenshrubs
>2 <0.1
gentlyrolling
Tussock Eriophorum 0.3-0.5 <0.3
flatlowlands
Wetsedge
graminoids 0.2-0.3 0.1-0.5
well-drainedalluvialsites
Shrub deciduousshrubs
>1 thin?
![Page 29: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/29.jpg)
Tundra vegetation-soil catenas
Sedge Shrub Sedge Tussock Heath
0 organics
sandysoil
permafrost
rockysoil
silty soilsilty soil
Depth (m)
1
2
Felsen-meer
![Page 30: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/30.jpg)
Felsenmeer vegetation dominated by lichens
![Page 31: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/31.jpg)
Evergreen heath tundra
Dominated by Ericaceae (heaths), such as Cassiope
![Page 32: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/32.jpg)
Heath tundra is floristically more diverse than other tundra types
![Page 33: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/33.jpg)
Tussock tundra
(dominated by Eriophorum)
[cotton grass]
![Page 34: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/34.jpg)
Wet sedge tundra:
dominated by graminoids (e.g. Carex, Dupontia)
![Page 35: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/35.jpg)
Animal life
![Page 36: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/36.jpg)
Surviving winterStrategy Organisms
Distant migration Local migration Above snow-pack
heavy insulation
protective colouring
Below snow-pack Hibernation Dormant phase
birds caribou
ground squirrelsplants, insects
muskox, polar bear
lemmings, voles
arctic fox, ptarmigan
![Page 37: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/37.jpg)
Are cyclical population dynamics
(~4 yr period)a product of simple food
webs?(note difference in time
scales)
Vole data: N. FinlandLemming data: N. Norway
![Page 38: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/38.jpg)
Lemming distribution
![Page 39: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/39.jpg)
The tundra phosphorus cycle
lemmings/ha 2-12 2-12 40-50 180-200 jaegers uncommon uncommon breeding breeding(pairs/km2) no breeding no breeding 10 40-50snowy owls scarce scarce breeding breeding(pairs/km2) no breeding no breeding 0.1 0.2shorteared absent absent 1 record 10/km2
owls
Active layer
Permafrost
CaCa
Ca
CaN
NN
N
P
PP
P
K KK
K
Forage (%P) 0.2 0.2 0.3 0.6quality
•• ••••Litter layer thin thick
![Page 40: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/40.jpg)
Caribou dynamics
The ANWR debate
![Page 41: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/41.jpg)
![Page 42: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/42.jpg)
Porcupine herd migrations: radio-collared females at calving grounds on
Arctic Alaska coastal plain
![Page 43: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/43.jpg)
Winter feeding grounds in Yukon, Porcupine caribou herd (1998-99)
300 k
m
![Page 44: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/44.jpg)
Snow goose dynamics
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Lesser snow goose flock
~4 M geese breed in the marshes of the
Canadian Arctic
birds
devegetatedarea
Jeffries et al., 2006. J. Ecol. 94, 234-242.
![Page 45: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/45.jpg)
Impacts of snow goose overgrazing
drying ofsurface soil
increasedsoil salinity
reduced graminoid
growth
reducedgraminoidbiomass
Intense grubbing andgrazing by snowgeese
![Page 46: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/46.jpg)
Effects of snow goose grazing and grubbing (James Bay)
Salicornia
Puccinellia
![Page 47: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/47.jpg)
Potential effects of climate change
Is climate change occurring in Arctic environments? - climate records short - biotic data fragmentary
Simulation modelsField experiments
![Page 48: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/48.jpg)
Recent (post-1950) climate change in polar regions
Arctic:• Reduction in sea ice extent and thickness• Northward treeline shifts (e.g. E. coast Hudson Bay)• Increased lake productivity (e.g. Ellesmere Island)• Range expansions (e.g. dragonflies - Inuvik - 2000)Antarctic:• Ice shelf disintegration (e.g. N. Larsen & Wordie
Shelf)• Spread of flowering plants (e.g. Antarctic hairgrass
has expanded its range 25-fold since 1964)• New lichen species colonizing recently deglaciated
areas
![Page 49: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/49.jpg)
Climate change
![Page 50: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/50.jpg)
Climate change in the western Canadian arctic
Data: Environment Canada
Inuvik, NWT
-40
-30
-20
-10
0
10
20
30
1950 1960 1970 1980 1990 2000 2010
Year
Temperature (°C)
Monthly Max. Temp. (°C)Mean Ann. Temp. (°C)Monthly Min. Temp. (°C)
![Page 51: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/51.jpg)
Climate change in the western Canadian arctic
Data: Environment Canada
Inuvik, NWT
0
50
100
150
200
250
300
350
400
1950 1960 1970 1980 1990 2000 2010
Year
Precipitation (mm)
Total Precip. (mm)
Snow (mm; water equivalent)
![Page 52: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/52.jpg)
Climate change in the eastern Canadian arctic
Iqaluit, Nunavut
-40
-30
-20
-10
0
10
20
1940 1950 1960 1970 1980 1990 2000 2010
Year
Temperature (°C)
Monthly Max Temp (°C)Mean Ann. Temp. (°C)Monthly Min Temp (°C)
Data: Environment Canada
![Page 53: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/53.jpg)
Climate change in the eastern Canadian arctic
Data: Environment Canada
Iqaluit, Nunavut
0
100
200
300
400
500
600
700
1940 1950 1960 1970 1980 1990 2000 2010
Year
Precipitation (mm)
Total Precip. (mm)
Snow (mm; waterequivalent)
![Page 54: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/54.jpg)
Source: www.metoffice.gov.uk/.../ images/figure5.jpg
Sea-ice extent, Arctic
and Antarctic oceans
![Page 55: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/55.jpg)
Source: Arctic Climate Impact Assessment website
![Page 56: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/56.jpg)
The Arctic of the future
![Page 57: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/57.jpg)
![Page 58: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/58.jpg)
![Page 59: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/59.jpg)
Field experiments:
ITEX sites
![Page 60: Polar ecosystems](https://reader035.fdocuments.in/reader035/viewer/2022062309/56814636550346895db344ec/html5/thumbnails/60.jpg)
Impacts of climatic warming (ITEX results [1997])
inc. seedweight and
viability
increasedgraminoidabundance
reduced evergreen shrub competitiveness
increasedplant
productivity
Increased airtemperature
reducedplant diversity