1. Ecology & the Biosphere
Chapter 18

2. Biomes Major terrestrial or aquatic life zone Aquatic biomes
Occupy roughly 75% of Earth’s surface
Freshwater
Marine
Terrestrial biomes
Classified based on vegetation type
Student Misconceptions and Concerns
1. Before addressing specific biomes, consider discussing some specific details about global weather patterns with references to the major factors that influence your local weather. Depending upon where you live, students may not understand the influences of mountains, large bodies of water, and latitude on weather.
2. Students may expect that similar biomes have similar species, a common misperception. As the text notes, the similarities in organisms between widely separated but similar biomes is much more likely due to convergent evolution.
Teaching Tips
1. Before lecturing about rivers and streams, ask students to speculate how the qualities of a stream change from its source to the point where it joins a larger body of water many kilometers downstream. In particular, how does water temperature, water clarity, water speed, and the types of fish compare as the water flows away from its source?
2. The removal and deposition of sediment in a river or stream reveals the importance of the speed of water. Near the out edge of a curve, a river or stream will erode the bank. However, when the river slows or along the slower inside of curves, sediment tends to deposit. The result is the winding nature of mature rivers. A satellite image of the Mississippi river reveals the extensive curvature of this old system.
3. Throughout the text, the sun has been generally considered as the primary energy input to ecosystems. Hydrothermal vent communities are a clear exception. Some students might enjoy additional details about the nature of these ecosystems and the roles they might have played in the early evolution of life on Earth. One source of good Internet information about hydrothermal vent communities is found at:
4. The turnover of lakes and ponds in the fall often results in noticeable changes that students may have observed. Fish kills and distinct changes in the colors and smells of the water may have been noticed by students in your course (depending upon your particular location). If you are addressing this subject in the fall or early winter, you might have students watch for this phenomenon.
5. Many web sites introduce the diversity of biomes with varying degrees of detail and imagery. Many related sites are targeted towards pre-college students. The following site lists links related to biomes (
6. Consider preparing a chart that will help your students compare the characteristics of the major terrestrial biomes. Helping students learn how to organize information may still be needed at the beginning levels of college.
7. Challenge your students to identify unpredictable natural disturbances in the terrestrial biomes examined. How is each biome adapted to recover? What components of each biome are dependent upon these natural disturbances? Exploring the role of disturbances in ecosystems may provide hope to students who may be saddened by human impacts on biomes.
8. In the 1960s and early 1970s, movies about the American west were produced in portions of Europe. Relying upon similar biomes in Europe and North America, these “spaghetti westerns” were made to look as if they were filmed in the American west. A Google search of “spaghetti westerns” will produce links to websites devoted to this genre of film.
9. A discussion of the movements of water through your local community might help students relate to the concept of global water cycling at a local level. Students could be asked to consider all of the possible inputs of water into your community and the possible routes of exit. Students may not realize that it is possible that the outflow of water from one community leads to the inflow of water in a community downstream.

3. Aquatic - Freshwater
Typically have a salt concentration of less than 1%
Standing water
includes lakes and ponds
Flowing water
rivers and streams
Wetlands
Cover less than 1% of Earth
Contain a mere 0.01% of its water
Harbor about 6% of all described species
Are used for drinking water, crop irrigation, sanitation, and industry

4. Photic
zone
Benthic
realm
Figure Zones in a lake
Aphotic
zone

5. Aquatic - Marine Typically have a salt concentration around 3% Oceans
Intertidal zones
Coral reefs
Estuaries

6. (seafloor from continental shelf to deep-sea bottom)
High tide
Low tide
Pelagic realm (open water)
Man-of-war
(to 50 m long)
Oarweed (to 2 m)
Turtle
(60–180 cm)
Sea star
(to 33 cm)
Brain coral
(to 1.8 m)
Photic
zone
Phyto-
plankton
Zoo-
plankton
Blue shark (to 2 m)
200 m
Sponges
(1 cm–1 m)
Sperm whale
(10–20 cm)
Intertidal
zone
Continental
shelf
Hatchet fish
(2–60 cm)
“Twilight”
Sea pen
(to 45 cm)
Octopus
(to 10 m)
Aphotic
zone
Gulper eel
(to 180 cm)
1,000–
4,000 m
Benthic realm
(seafloor from continental
shelf to deep-sea bottom)
Sea spider
(1–90 cm)
Rat-tail fish
(to 80 cm)
Figure Ocean life
Brittle
star
(to 60 cm)
Anglerfish
(45 cm–2 m)
No light
Glass
sponge
(to 1.8 m)
Sea cucumber
(to 40 cm)
Tripod fish
(to 30 cm)
6,000–
10,000 m

7. Terrestrial Tropical Forest Savanna Desert Chaparral
Temperate Grassland
Temperate broadleaf forest
Coniferous forest
Tundra
Polar ice

8. Temperate broadleaf forest Savanna Coniferous forest Desert
Tropic of
Cancer
Equator
Tropic of
Capricorn
30º S
Figure Map of the major terrestrial biomes
Key
Tropical forest
Temperate broadleaf forest
Savanna
Coniferous forest
Desert
Arctic tundra
Chaparral
High mountains (coniferous forest and
alpine tundra)
Temperate grassland
Polar ice
Figure 18.27

9. Tropical Rainforest occur in equatorial areas temperature is warm
days are 11–12 hours long year-round
cm rain
inches

10. Savannas dominated by grasses and scattered trees warm year-round
Experience cm rainfall
12–20 inches
dramatic seasonal variation

11. Deserts driest of all biomes Less than 30 cm
12 inches
May be very hot or very cold
140 to -22 F

12. Temperate Grasslands mostly treeless 25-75 cm rain per year
10–30 inches
Experience frequent droughts and fires
characterized by grazers including bison and pronghorn in North America

13. Temperate Broadleaf Forest
Occurs throughout midlatitudes
sufficient moisture to support the growth of large trees
cm rain
30-60 inches
Includes dense stands of deciduous trees in the Northern Hemisphere

14. Coniferous Forest “Temperate rainforest”
dominated by cone-bearing evergreen trees
Includes the taiga
largest terrestrial biome on Earth

15. Tundra
Covers expansive areas of the Arctic between the taiga and polar ice
characterized by
Permafrost
permanently frozen subsoil
Bitterly cold temperatures
High winds

16. Polar ice high latitudes
north of the arctic tundra in the northern hemisphere
Antarctica in the southern hemisphere
Only a small portion of these land masses is free of ice or snow
Even in summer!