Chapter 20 Terrestrial Biomes

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Chapter 20Terrestrial Biomes

• Geosystems 6e
• An Introduction to Physical Geography

Robert W. Christopherson Charles E. Thomsen
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Terrestrial Biomes

• Biogeographic Realms geographic region where a
  group of plant and animal species have evolved
  generally correspond to continents  
• There are no rigidly defined boundaries between
  realms transition zones
• Ecotone boundary transition zone between
  adjoining ecosystem regions

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Biogeographic Realms

• Terrestrial Ecosystems self-sustaining
  association of land-based plants and animals and
  their abiotic environment characterized by
  specific plant formation classes
• Biome large, stable terrestrial ecosystem
  characterized by specific plant and animal
  communities  

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Biomes

• Usually named for dominant vegetation
• 6 broad biomes forest, savanna, grassland,
  shrubland, desert, and tundra
• These divided into more specific vegetation units

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Earths Major Terrestrial Biomes

• Equatorial and Tropical Rain Forest  
• Tropical Seasonal Forest and Scrub  
• Tropical Savanna  
• Midlatitude Broadleaf and Mixed Forest  
• Needleleaf Forest and Montane Forest  
• Temperate Rain Forest  
• Mediterranean Shrubland  
• Midlatitude Grasslands  
• Deserts  
• Arctic and Alpine Tundra 

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Tropical Savanna
Figure 20.3
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Tropical Savanna Climates

• South Florida
• Influenced by ITCZ
• Two temperature maximum
• Grasslands with scattered, drought-resistant
  trees
• Transitional biome between tropical forests and
  semiarid regions
• Savanna originally covered 40 of land

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Tropical Savanna Biome

• Better agricultural soils
• Sorghum, wheat, peanuts
• Xerophytic plants
• Small, thick leaves rough bark waxy or hairy
  leaf surfaces
• Under the influence of the ITCZ for 6 months
• Convectional thunderstorms
• Semi-permanent high pressure

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Tropical Savanna Biome

• Serengeti Plains
• Sahel Region
• Home to large land mammals
• Zebras, giraffe, buffalo, elephant, lions,
  cheetahs, ostrich, crocodile

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Midlatitude Broadleaf and Mixed Forest

• Southeastern US, Atlantic coastal plain, New
  England, and Great Lakes region
• Pines historically dominated the coastal plain
• A more even mix of hardwoods and pines occurs
  farther north and inland
• Red fox, white-tailed deer, flying squirrel,
  possum, bear, cardinal

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Broadleaf Mixed Forest
Figure 20.9
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Midlatitude Broadleaf and Mixed Forest
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Midlatitude Broadleaf and Mixed Forest

• Deciduous broadleaf trees are common, such as
• Many, many oak species
• All hickories
• Maples (red and sugar)
• Elms
• Pines and other conifers are also important.
• Poor agricultural soils
• Pine plantations

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Needleleaf Forest and Montane Forest

• In northern North America and northern Eurasia,
  the closed-canopy version of this forest is
  called boreal forest.
• In the transitional forests in the higher
  latitudes, the more open version of this forest
  is called taiga.
• This biome is also found in higher elevations and
  is called montane forest.

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Needleleaf Forest and Montane Forest
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Needleleaf Forest and Montane Forest

• Consist almost exclusively of needleleaf trees
• Pines
• Spruces
• Firs
• Larches

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Temperate Rain Forest
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Temperate Rain Forest

• Dense forests of firs, cedars, hemlocks, and
  spruces dominate
• Persistent moisture, humidity in understory (lots
  of moss)
• In Pacific Northwest, called the coastal
  evergreen forest
• Some of the largest trees in the world exist here
• Lower biodiversity than tropical rain forest
• Thick undergrowth - ferns

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Mediterranean Shrubland
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Mediterranean Shrubland

• aka temperate shrubland, chaparral
• Woody shrubs and grassy woodlands
• Important for agriculture
• Fire adapted species
• Deep rooted with sprouting capabilities
• schlerophyllous

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Midlatitude Grasslands
Figure 20.15
Figure 20.16
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Midlatitude Grasslands
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The Grassland Biome

• 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.
• Soils found in grasslands are some of the most
  fertile in the world, though.
• Tallgrass and shortgrass prairie in U.S.

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Deserts

• Camel, bighorn sheep, kangaroo rat, scorpion,
  snakes, and roadrunners
• Most animals are nocturnal to avoid high
  temperatures cold-blooded animals
• Low organic content of the soil high salt
  content
• Xerophytes
• Warm deserts tropics, subtropics
• Cold deserts midlatitudes

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The Desert Biome
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Desertification

• 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.

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Arctic and Alpine Tundra
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Arctic Tundra

• Associated with high latitudes
• 60-80 day growing seasons
• No trees, dwarf plants, soggy ground
• Low temperatures, precipitation, and evaporation
• Poorly developed soils underlain by permafrost

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Arctic Tundra

• Tundra vegetation mosses, sedges, snow lichen,
  arctic meadow grass
• Musk ox, caribou, reindeer, weasels, rabbits,
  polar bears, and mosquitoes
• Important breeding ground for migratory birds
  geese, swans, waterfowl

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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
• Mountain goats, bighorn sheep, elk, voles

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End of Chapter 20

• Geosystems 6e
• An Introduction to Physical Geography

Robert W. Christopherson Charles E. Thomsen