Page 118 - Environment: The Science Behind the Stories

(a) Boreal forest 80 (a) Chaparral 120

Mean monthly temperature (ºC) –10 40 Mean monthly precipitation (mm) Mean monthly temperature (ºC) 40 80 Mean monthly precipitation (mm)
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(b) Archangelsk, Russia (b) Los Angeles, California, USA
Figure 4.27 Boreal forest experiences long, cold winters, Figure 4.28 Chaparral is a highly seasonal biome dominated
cool summers, and moderate precipitation. Climatograph adapted by shrubs, influenced by marine weather, and dependent on
from Breckle, S.W., 2002. fire. Climatograph adapted from Breckle, S.W., 2002.

Boreal forest The northern coniferous forest, or boreal ringing the Mediterranean Sea, chaparral occurs along the
forest, often called taiga (Figure 4.27), extends across much of coasts of California, Chile, and southern Australia. Chapar-
Canada, Alaska, Russia, and Scandinavia. A few species of ever- ral communities experience frequent fire, and their plants
green trees, such as black spruce, dominate large stretches of are adapted to resist fire or even to depend on it for germi-
forest, interspersed with occasional bogs and lakes. These for- nation of their seeds.
ests develop in cooler, drier regions than do temperate forests,
and they experience long, cold winters and short, cool summers. Altitude creates patterns analogous
Soils are typically nutrient-poor and somewhat acidic. As to latitude
a result of strong seasonal variation in day length, temperature, CHAPTER 4 • S PEC i ES i n TERA CT i on S A nd Co mmuni T y E C ology
and precipitation, many organisms compress a year’s worth of As any hiker or skier knows, climbing in elevation causes a
feeding, breeding, and rearing of young into a few warm, wet much more rapid change in climate than moving the same dis-
months. Year-round residents of boreal forest include mam- tance toward the poles. Vegetative communities change along
mals such as moose, wolves, bears, lynx, and rodents. This mountain slopes in correspondence with this altitude-induced
biome also hosts many insect-eating birds that migrate from climate variation (Figure 4.29). It is often said that hiking up
the tropics to breed during the brief, intensely productive, a mountain in the southwestern United States is like walking
summer season. from Mexico to Canada. A hiker ascending one of southern
Arizona’s higher mountains would begin in Sonoran Desert
Chaparral In contrast to the boreal forest’s broad, con- or desert grassland and proceed through oak woodland, pine
tinuous distribution, chaparral (Figure 4.28) is limited to forest, and finally spruce–fir forest—the equivalent of pass-
small patches widely flung around the globe. Chaparral ing through several biomes. A hiker scaling one of the great
consists mostly of evergreen shrubs and is densely thick- peaks of the Andes in Ecuador, near the equator, could begin
eted. This biome is highly seasonal, with mild, wet win- in tropical rainforest and end amid glaciers in alpine tundra.
ters and warm, dry summers—a climate induced by oceanic At higher altitudes, temperature, atmospheric pressure,
influences and often termed “Mediterranean.” Besides and oxygen all decline, whereas ultraviolet radiation increases. 117

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