Chapter 16:  Ecosystems and Biomes
 
Part-2:  Biomes

    10-31-001

 [ Exam-3 Coverage ]    [ Geog-100 Home ]

Earth's Major Terrestrial Biomes

Advisory:  

• The graphics and photos in the chapter ARE important!  

• You should view them and evaluate the messages they convey.

Complexities:

• This part of Chapter 16 stretches your capacity to recall what we have covered in this course to date and to relate it to the world-wide distribution of major land-based biomes.

• Hence you need to read the chapter several times along with focused studying.

Table 16-2: Major Terrestrial Biomes and Their Characteristics

• The text's author prepared this concise table for your benefit.  Use it!

  • The organization of the table represents most of HOW I think YOU should THINK about the 10 biomes presented in this chapter.

  • My exceptions are these:

    • Köppen climate codes:  If you cannot scope these out in your mind, make sure you know the word names for them, at the least, as for example, Aw = Savanna, Tropical Wet and Dry.

    • Soils:  I am not interested in you studying this column in the Table.

    • Annual Precipitation Range:  Ditto, soils.

    • Water Balance:  Ditto, soils.

• Hence, to consider Biomes and Ecosystems in this chapter, one needs to:

  • know their names

  • know their vegetation characteristics

  • correlate these with the Köppen climate types

    • Here it probably will be more useful for you to specially correlate the biomes and ecosystems to the temperature and precipitation patterns described for the climates.

Study methods:

• I recommend that you use "flash cards," at least one per biome/ecosystem.  Put the biome name on one side, characteristics as from Table 16-2 on the other side of the card.

• Read and re-read, and highlight the text, make sure you understand the meanings embodied in the illustrations.

Earth's Major Terrestrial Biomes

Again, please DO read the text about that which follows.  You will get MUCH more meaning than be just studying the Table on page 517.

Terrestrial Ecosystem Concepts

• Why study biomes?  

  • They represent what is "natural," what would likely be present if humans had not modified the physical environment.

  • They give us a standard against which to compare our unstable, human invoked biotic environments.

• Terrestrial Ecosystem: 

  • Self-regulating association of plant and animals and their abiotic environment characterized by specific plant formations.

  • Plants in their growth, form and distribution, reflect our world's physical systems:

    • Earth's energy patterns

    • Earth's atmospheric composition

    • Earth's temperature and winds

    • Earth's air masses

    • Earth's water quantity, quality and seasonal timing

    • Soils

    • Regional climates

    • Geomorphic (landforming) processes

    • Ecosystem dynamics

• Biome: 

  • A large, stable ecosystem

  • Characterized by specific plant and animal communities

  • Usually named for dominant vegetation

  • Plant species can be generalized into six, very broad biomes:

    • Forest

    • Savanna

    • Grassland

    • Shrubland

    • Desert

    • Tundra

• Ecotone

  • The primary concept here is that the divisions between biomes and ecosystems are NOT SHARP LINES.

  • An ecotone is a boundary transition zone between adjoining biomes or ecosystems.

• Formation Classes

  • Subdivisions of biomes that refer to the dominant plants.

  • "Tropical Rain Forest" is one example.

• Life-form designations for plants

  • Designations for plants based on outward physical properties of plants or vegetation cover.

  • Trees, lianas, shrubs, herbs, bryophytes, epiphytes, thallophytes 
    (See p 512, top right)

• World Map: Ten Major Terrestrial Biomes (Fig 16-22): 

  • Based on formation classes

  • Many similarities to the world maps of climates and of precipitation, as should be expected

Fig 6-5:  World Climates According to Köppen

World Biomes

 

Biome 1] Equatorial and Tropical Rain Forest

Fig 6-6: Tropical Rainforest Northwestern Brazil

This biome equates largely to Köppen's Af climate: Equatorial Wet, or, Tropical Rainforest Distribution correlates much with the Intertropical Convergence zone and its sunlight and precipitation. There is a vertical distribution of ecological niches.

 

Fig 6-23: Vertical Zonation in Tropical/Equatorial Rainforest Canopy

Different plants have adapted to different elevation layers.  Think about the quest for sunlight for plant photosynthesis.  How much opportunity is there for sunlight to strike the surface.  Therefore, how lush should plant-life be on the actual ground surface?

 

Fig 16-25:  Rainforest Losses Due to Deforestation Photos from Western Brazil

Be sure to study Focus Study 16-1:  Biodiversity and biosphere reserves Trees harvested to clear land for "development." Some woods highly desirable for fine furniture and the like. Reduces major source of atmospheric regeneration via "fixing" carbon dioxide and replenishing oxygen.

 

2] Tropical Seasonal Forest and Scrub

• On the margins of the rain forest

• Regions of low and erratic rainfall

• Highly varied; difficult to portray

3] Tropical Savanna

• Notice on the map that his includes the southern tip of Florida!

• This is a transition zone between tropical forests and semiarid steppes and deserts

• Savanna is large area of open grasslands and in some cases, scattered trees

• Occurs in Africa South America,  India, Australia and a few other small pockets

• This is the "big game" country of Africa. 

4] Midlatitude Broadleaf and Mixed Forest

• This corresponds to Köppen's Cf and Cw climates

• This comprises deciduous (leaf losing) trees plus deciduous and needle trees.

• Example:  Forests of central and eastern USA

West Virginia Scene

Deciduous Forest and Soybeans, Indiana

5] Needleleaf Forest and Montane Forest

• Band across high latitudes of North America, Asia and European Russia

• Also known as the boreal forest and the northern forest

• Occupy some of Köppen's "D" climates.

Northern/Boreal Forest, Canada

• At northern margins, this is called taiga as trees are spread out as this zone transitions into tundra

Taiga, or Northern Forest

6] Temperate Rain Forest

• Only in the narrow coastal margins of the Pacific Northwest

• World's tallest trees here -- California Redwoods

• Another type of "rainforest" in the Olympic Peninsula of Washington state:  midlatitude rainforest

• Corresponds to Köppen's Cfb, Cfc climates

7] Mediterranean Scrubland

• Köppen's Csa and Csb climates with hot-dry summers, moist winters, mild temperatures.

• On poleward side of the subtropical pressure zones.

• Heat and drought foster brushy, tough, drought-resistant plants.

• Eucalyptus native in Australia; chaparral in California

 
Eucalyptus Stand, Mediterranean Climate, Australia

 
Oak Savanna, Sierra Foothills, California

Chaparral, Mediterranean Climate, California

8] Midlatitude Grasslands

• Most modified by humans of the world's biomes -- now the "breadbaskets" of the world.

• Tall-grass prairie is one variety --- Grasses were up to 6 feet plus tall in central U.S.

9] Desert Biomes

• Warm Desert and Semidesert (Steppe)

Death Valley, California

 
Sonoran Desert, Arizona

 
 
Hot Low-latitude Steppe, Australia

• Cold Desert and Semidesert

Cold Midlatitude Desert, West of Ely, Nevada

 10] Arctic and Alpine Tundra

• Köppen's ET or tundra climate.

• Beyond the tree line; temperatures, moisture and length of growing season do not support trees.

• At high, northern latitudes, plus, above the tree line in lower latitude, mountain situations.

 

Winter and Summer, Tundra-Taiga Transition, Hudson Bay

Alpine Tundra, Mt. Evans, Colorado

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