Environmental Engineering Reference
In-Depth Information
By comparing Figure 5-7 with Figure 5-2 and Fig-
ure 1 in Science Supplement 2 at the end of this topic,
you can see how the world's major biomes vary with
climate. Figure 3-8 (p. 41) shows major biomes in the
United States as one moves through different climates
along the 39th parallel.
Average annual precipitation and temperature (as
well as soil type; see Figure 3-22, p. 52) are the most
important factors in producing tropical, temperate, or
polar deserts, grasslands, and forests (Figure 5-8).
On maps such as the one in Figure 5-7, biomes are
depicted as having sharp boundaries and being cov-
ered with the same general type of vegetation. In reality,
biomes are not uniform.
They consist of a
mosaic of patches,
each having a somewhat different biological commu-
nity but sharing similarities unique to the biome. These
patches occur mostly because the resources that plants
and animals need are not uniformly distributed and
because human activities remove and alter natural
vegetation.
Figure 5-9 shows how climate and vegetation vary
with
latitude
(distance from the equator) and
altitude
(elevation above sea level). If you climb a tall mountain
from its base to its summit, you can observe changes in
plant life similar to those you would encounter in trav-
eling from the equator to the earth's poles.
Polar
Tundra
Subpolar
Temperate
Coniferous forest
Desert
Grassland
Deciduous
forest
Tropical
Chaparral
Desert
Savanna
Rain forest
Tropical
seasonal
forest
Scrubland
Figure 5-8
Natural capital:
average precipitation and average temperature, acting together as limiting fac-
tors over a period of 30 or more years, determine the type of desert, grassland, or forest biome in a particular
area. Although the actual situation is much more complex, this simplified diagram explains how climate deter-
mines the types and amounts of natural vegetation found in an area left undisturbed by human activities. (Used
by permission of Macmillan Publishing Company, from Derek Elsom,
The Earth,
New York: Macmillan, 1992.
Copyright © 1992 by Marshall Editions Developments Limited.)
