Visualizing Environmental Science

128 CHAPTER 6 Ecosystems and Evolution

Earth’s Major Biomes

LEARNING OBJECTIVES

Near the poles, temperature is generally the

overriding climate factor defining a biome, whereas in

temperate and tropical regions, precipitation is more

significant than temperature, as shown in Figure 6.2.

Light is relatively plentiful in biomes, except in certain

environments such as the rainforest floor. Other abiotic

factors to which certain biomes are sensitive include

extreme temperatures as well as rapid temperature

changes, fires, floods, droughts, and strong winds.

Elevation also affects biomes: Changes in vegetation

with increasing elevation resemble the changes in vegeta-

tion observed in going from warmer to colder climates.

These differences across biomes can be further defined

by types of vegetation present and land use pat-

terns (Figure 6.3 on pages 130 and 131).

We now consider nine major biomes and

how humans are affecting them: tundra, bo-

real forest, temperate rain forest, temperate

deciduous forest, temperate grassland, chap-

arral, desert, savanna, and tropical rain forest.

1. Define biome and discuss how biomes are
   related to climate.


2. Briefly describe the nine major terrestrial
   biomes, giving attention to the climate, soil,
   and characteristic organisms of each.

E

arth has many different climates—long-term
wheather patterns—based primarily on tem-
perature and precipitation differences. Char-
acteristic organisms have adapted
to each climate within large regions called bi-
omes. Each biome encompasses many interact-
ing ecosystems (Figure 6.1). In terrestrial
ecology, a biome is considered the next level of
ecological organization above community,
ecosystem, and landscape.

0

0 1000 2000 Kilometers

1000 2000 Miles

0 ° 0 °

(^30) ° S
30 ° N
60 ° N
(^60) ° S
30 ° S
(^30) ° N
(^60) ° N
60 ° S
Tundra
Boreal forest
Temperate deciduous forest
and temperate rain forest
Temperate grassland
Chaparral
Desert
Tropical rain forest
Tropical dry forest
Savanna
Mountains with
complex zonation
Based on data from World Wildlife Fund.
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Although sharp boundaries are shown in this highly simplified map, biomes actually grade together at their boundaries.
Use the legend below to identify the locations of the different biomes.
biome A large,
relatively distinct
terrestrial region with
similar climate, soil,
plants, and animals,
regardless of where it
occurs in the world.