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in summer, many of the species in this biome are adapted to fire,
which, as in the case of tropical savanna, recycles nutrients in
the system. Some plant species in the Mediterranean woodland
and shrub biome have seeds that germinate only after they are
stimulated by the heat of a fire.
Another kind of midlatitude coniferous forest exists in
the southeastern part of the United States within the humid
subtropical hot-summer climate ( Cfa, Cwa ) zone. This for-
est is called the southeastern coniferous forest and stretches
across southeastern Louisiana, southern Mississippi, southern
Alabama, central and southern Georgia, and the Florida pan-
handle on sandy sites that do not hold much water. The biologi-
cal diversity in this region is very high, with the dominant tree
species being longleaf pine that has an understory of wiregrass
(see Figure 9.7 again). Needles in these trees come in bunches
of three and are remarkably long, ranging from 20 cm to 45 cm
(8 in. to 18 in.) in length.
Midlatitude Coniferous Forest Biome The last major
subdivision in the midlatitude forest biome is the midlatitude
coniferous forest. This plant community consists largely of
needle-leaf evergreen trees and is found in places like the west
coast and mountains of North America, the southeastern United
States, and eastern Europe (see Figure 10.6). Coniferous for-
ests in North America's mountainous areas are associated with
humid continental mild-summer climate ( Dfb ) and have short
growing seasons. Some of these coniferous forests occur at
relatively low latitudes because temperatures are cool at high
elevations. In North America, mountain forests include species
such as Douglas fir and ponderosa pine (Figure 10.12a). On the
west coast of North America, these forests are associated with
the marine west coast climates ( Cfb , Cfc ), where annual precip-
itation is between 150 cm and 500 cm (60 in. and 197 in.) and
average annual temperatures are mild for a midlatitude loca-
tion. Given the cool, moist environment in this region, the for-
est is often referred to as temperate rainforest (see Figure 9.9).
This forest also contains significant stands of deciduous trees,
such as the giant redwoods in northern California and southern
Oregon (Figure 10.12b).
Boreal Forest Biome The last major forest biome is the
boreal forest biome. The global distribution of this biome is
closely associated with the subarctic climates ( Dfc , Dwc , Dwd ),
and is the broad expanse of coniferous forest that occurs across
Alaska, Canada, and Russia (see Figure 10.6). This vegetation
assemblage is located entirely within the higher midlatitudes
in the Northern Hemisphere because the large continents have
very cold winter temperatures and relatively low rainfall. If you
recall, the Southern Hemisphere contains no large landmasses,
other than frigid Antarctica, at high latitudes. As a result, this
hemisphere has no large expanse of subarctic climate and thus,
no boreal forest biome.
The boreal forest biome, or taiga in the Russian
language, has the least diverse assemblage of plants of any
(b)
Figure 10.12 Examples of the midlatitude coniferous forest biome.
(a) This stand of ponderosa pine in California's Sierra Nevada is a great
example of an alpine midlatitude coniferous forest. (b) Giant redwoods
in northern California. These trees are over 100 m (350 ft) tall and can be
over 6 m (20 ft) in diameter!
(a)
 
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