Physical Geographyby Alan Arbogast

Chapter 10 con’t

Biomes

Lawrence McGlinnDepartment of GeographyState University of New York - New Paltz

Geography of Biomes

Grassland Biomes• Midlatitude Grassland – dominant vegetation is

grass – dry parts Dfa, Dwa, Dfb, Dwb climates, and Bsk climate – central N. America, South Africa, eastern Europe, central Asia, Argentina

• Precipitation great enough to support grasses and some trees, but not forests.

• Drought and fire prevent large forests from growing.

• Fires are very common in the grassland biome.• Grasses can survive fires because they grow

from the bottom instead of the top.• Soils found in grasslands are some of the most

fertile in the world, though.• Tallgrass and shortgrass prairie in U.S.

Midlatitude Grassland

Midlatitude Grassland Biome

Shortgrass prairie Tallgrass Prairie

Geography of Biomes

Deserts

• Where are they located?

– Continental areas

– Areas dominated by STHP

– Rainshadows (leeward sides of mountains)

Deserts

• Most animals are nocturnal to avoid high temperatures

• Many cold-blooded animals

• Low organic content of the soil; high salt content

• Warm deserts = tropics, subtropics

• Cold deserts = midlatitudes

• Types of plants in deserts:

• All generally classified as Xerophytes– Phreatophytes: plants that grow along water

courses (deep tap roots)– Ephemerals: plants that wait years for rainfall

events– Succulents: plants that store water for long

periods to survive continued aridity– Halophytes: plants specifically adapted to the

very salty environment often found in deserts

Desert Biome

Desert Biomes

• Hot & Dry Desert – subtropical, centered on 30º N & S – Bwh climate – Sahara, Kalahari, Mohave Deserts – bare ground to xerophytic plants

Warm Desert and Semidesert

• Caused by the low precipitation and dry air of subtropical high pressure

• These areas are under the influence of high pressure 8 to 12 months of the year

• Coastal deserts, such as the Atacama, western Sahara, and Namib Deserts receive precipitation in the form of sea mist and fog

Desert Biomes• Semi-Arid & Cold Desert – western N.

America & central Asia – Bwk climate – bare patches to low, spiny, wooly plants, e.g. mesquite, sagebrush, creosote bush

Cold Desert and Semidesert

• Occur at higher latitudes

• Affected by subtropical high pressure less than 6 months of the year

• Rainshadow and interior location produced the cold deserts of the Great Basin.

• Light winter snow can occur over cold deserts

• Many of these deserts were former shortgrass prairies → overgrazing

Desertification

• Expansion of the desert

• Occurs along the margins of semiarid and arid lands

• Caused by poor agricultural practices, such as: overgrazing, soil overuse/abuse, improper management of soil moisture, erosion, salinization, deforestation, and climate change.

Geography of Biomes

Tundra Biome• Borders Arctic Ocean across N. American &

Russia – ET climate – grasses, shrubs, sedges, mosses, & lichens all short – easily damaged

Arctic Tundra

Figure 20.18

Arctic Tundra

• Associated with high latitudes

• Found in extreme northern Russia, North America, Europe, and Greenland

• 60-80 day growing seasons

• No trees, dwarf plants, soggy ground

• Low temperatures, precipitation, and evaporation

• Poorly developed soils underlain by permafrost

• Tundra vegetation: mosses, sedges, snow lichen, arctic meadow grass

• Important breeding ground for migratory birds: geese, swans, waterfowl

Arctic Tundra

Alpine Tundra

Figure 20.19

Alpine Tundra

• Associated with high elevations; above timberline

• Similar composition to Arctic Tundra

• No permafrost, better drainage

• Andes, White Mts of California, Alps, Himalayas

• Vegetation: grasses, herbs, stunted shrubs