Biomes

Biomes
Arctic Tundra
Houghton and Skole (1990) and Schlesinger (1997)
Tundra
• Lowest diversity (# species/area) 3% worlds species
• Lowest net primary production (10-400 g/m2/yr)
• Limited harsh environment
• Growing season: 2-3 months
• Soils—permafrost, inceptisols and entisols
Tundra regions:
Climate
• short growing season (6-10 weeks)
• 2 months of continuous daylight
• long, cold, dark winters
Mean annual Temp
-20 C to -50 C
Mean annual Ppt
10-50 cm
Moisture source:
summer rain & thaw
Climograph
20
100
18
90
16
80
14
70
12
60
10
50
8
40
6
30
4
20
2
10
0
Temperature
Precipitation (Inche
Barrow, Alaska
Elevation: 31 feet
Latitude: 71 18N Longitude: 156 47W
Ft - Tundra
0
J
F
M
A
M
J
J
A
S
O
N
D
Monthly Average Spanning 47 Years
Mean annual temp = -20º C to - 50 º C
Mean annual precipitation = 10 to 50 cm
(mostly summer & snow melt)
Mechanical weathering
poor soil development
Entisols/Inceptisols
poorly developed
Inceptisols: “embryonic” soils
Entisols: recent soils
Photo from USDA NRCS
Perennial, dark colored leaves
Lichen: symbiotic relation between algae and fungus
Alpine Tundra
•Thin soils
•Different climate from Arctic Tundra
•Freeze-thaw cycles operate on diurnal & seasonal cycle
Colorado Rockies
Arctic Animals
Rangifer tarandus
Branta ruficollis
Ovibos moschatus
Ursus arctos
Arctic Tundra vs. Alpine
High latitudes (lowlands & highlands)
Mountain Tops mid and low latitudes
Large land area
Small land area
Short growing season b/c of day length
Short growing season b/c snow pack
Low light intensity
High light intensity (especially UV)
Less precipitation
Greater precipitation (as snow)
Permafrost
Permafrost is rare
Human impacts in the Arctic
• Warmer temperatures cause accelerated thermokarst
erosion = subsidence of terrain caused by thawing of
frozen ground
• Little impact prior to 19th century. Native people
maintained low population density
• Three periods of human impact in the Arctic:
Early mining period (Alaska Gold Rush – 1870 to 1920s)
WW II Military bases built throughout Alaska (1930s and 1940s)
Oil and Natural Gas exploration (1960’s to present)
Northern Conifer Forest/Taiga
Houghton and Skole (1990) and Schlesinger (1997)
100
18
90
16
80
Saint John, New Brunswick
Elevation: 358 feet
Latitude: 45 19N Longitude: 065 53W
Dcb - Moist Continental
14
12
10
60
50
6
20
4
18
2
16
0
14
12
40
J
F
M
A
M
J
J
A
S
O
N
D
Monthly Average Spanning 12 Years
10
30
100
20
90
10
80
0
70
60
50
8
Temperature
8
40
6
30
Ottawa, Ontario
Elevation: 374 feet
Latitude: 45 19N Longitude: 075 40W
Dcb - Moist Continental
4
2
0
J
F
M
A
M
J
J
A
20
10
0
S
O
N
D
Monthly Average Spanning 21 Years
20
Precipitation (Inche
70
Temperature
20
100
18
90
16
80
14
70
Climate considered “subarctic”
10
growing season temperatures are cool
8
6
annual precipitation is low (25-75 cm )
4
12
60
50
40
30
20
2
10
0
0
J
F
M
A
M
J
J
A
Monthly Average Spanning 21 Years
S
O
N
D
Temperature
Precipitation (Inche
Precipitation (Inche
Fort Nelson, British Columbia
Elevation: 1253 feet
Latitude: 58 50N Longitude: 122 35W
E- Boreal, Subartic
Source Regions
for North American
Air Masses
Precipitation:
Continental(dry)
Maritime(moist)
Temperature:
Tropical (warm)
Polar (cold)
Arctic (very cold)
Boreal Forest/Taiga
•
•
•
•
45 to 70 degrees Latitude
Low diversity (2-4 tree species)
NPP (400-2000 g/m2/yr)
Limited by growing season to north (3-4
months/yr); competition to south
• Soil: spodosol (podzolization)
Moderate Precipitation
Iron rich hard pan layer
Podzolization
General Soil horizons
O
A
E
B
C
R
= organic
= humus/clay
= wash out (eluviation)
= accumulation (illuviation)
= weathered bedrock
= Regolith or bedrock
Common trees of the
boreal forest
Vegetation adaptations:
evergreen needleaf
thick cuticle – xeromorphic leaves