Page 113 - Environment: The Science Behind the Stories

Climate influences the locations Aquatic and coastal systems
of biomes resemble biomes

Which biome covers each portion of the planet depends on a In our discussion of biomes, we will focus exclusively on ter-
variety of abiotic factors, including temperature, precipitation, restrial systems because the biome concept, as traditionally
atmospheric and oceanic circulation patterns, and soil charac- developed and applied, has been limited to terrestrial systems.
teristics. Among these factors, temperature and precipitation However, areas equivalent to biomes also exist in the oceans,
exert the greatest influence (Figure 4.18). Because biomes are along coasts, and in freshwater systems. One might consider the
largely a function of climate, and because temperature and shallows along the world’s coastlines to represent one aquatic
precipitation are the best indicators of an area’s climate, sci- system, the continental shelves another, and the open ocean,
entists use climate diagrams, or climatographs, to depict such the deep sea, coral reefs, and kelp forests as still others. Many
information. coastal systems—such as salt marshes, rocky intertidal commu-
Global climate patterns cause biomes to occur in large nities, mangrove forests, and estuaries—share both terrestrial
patches in different parts of the world. For instance, temper- and aquatic components. And freshwater systems such as those
ate deciduous forest occurs in eastern North America, Europe, of the Great Lakes are widely distributed throughout the world.
and eastern China. Note in Figure 4.18 how patches represent- Unlike terrestrial biomes, aquatic systems are shaped not
ing the same biome tend to occur at similar latitudes. This by air temperature and precipitation, but by water tempera-
is due to Earth’s north–south gradients in temperature and to ture, salinity, dissolved nutrients, wave action, currents, depth,
atmospheric circulation patterns (p. 473). light levels, and type of substrate (e.g., sandy, muddy, or rocky

Tropical rainforest
Tropical dry forest

Temperate deciduous forest
Savanna

Temperate rainforest
Chaparral

Boreal forest
Temperate grassland

Desert
Tundra

Figure 4.18 Temperature and precipitation are the main factors determining which biome occurs in
an area. As precipitation increases, vegetation becomes taller and more luxuriant. As temperature increases,
types of plant communities change. For instance, deserts occur in dry regions; tropical rainforests occur in
112 warm, wet regions; and tundra occurs in the coldest regions.

M04_WITH7428_05_SE_C04.indd 112 12/12/14 2:55 PM