Geography Reference
In-Depth Information
Figure 2-18
High in the Indian Himalayas—15,000 feet (4,500 m)—
a horse grazes on vegetation far above the tree line.
Rich in grasses and flowers in summer , this terrain
is covered with ice and snow in the winter months.
Photograph courtesy of B. A. Weightman.
locations. Deciduous trees drop their leaves in the cold
season, using winter dormancy to survive until the warm
days of spring. Oak, birch, and elm are three of the more
familiar varieties. Needle trees such as pine, fir, and
spruce exist in cooler northern regions and at higher ele-
vations. There are nearly 2,000 woody plants in China' s
forests alone. These forests are important for both wood
and non-wood products. Ginkgo, chestnuts, walnuts,
tallow oil, tung oil, and birch juice are some of these. The
vast majority of mid-latitude forests have been elimi-
nated or damaged for the benefit of large human popula-
tions in these parts of the world.
plate of Antarctica, Australia, and New Guinea split
apart, leaving Antarctica behind. The Australia-New
Guinea section collided with southeastern Laurasia,
thereby creating the Malaysian and Indonesian archipel-
agoes. The collision took place just west of Sulawesi.
This undersea fracture marks the division between
Laurasian and Gondwanan faunal types. As mentioned
earlier in this chapter, India, once part of Gondwanaland
(Africa), crashed into Laurasia as well. In the process,
India served as a raft carrying Gondwanan fauna to
Laurasia.
Western and eastern Malesia (Malaysia and Indonesia)
have strikingly different animal communities. Plant dif-
ferences are not as distinct because plants more readily
disperse across water. A combination of Gondwanan and
Laurasian fauna inhabits the western region, while
Laurasian live in the east. Here, animals such as the
tree kangaroo and pygmy glider have similarities with
Australian species.
The British naturalist Alfred Russel Wallace ex-
plored both South American and Southeast Asian rain
forests. During his stint in Asia (1854-1862), Wallace
discovered these two distinct zoogeographic regimes.
He described their fauna as having “endless eccentrici-
ties of form and extreme richness of colour.” The line of
demarcation between the two zones is known as the
Wallace Line .
Thousands of wildlife species live in Asia, many not
yet identified. Many are endemic —they occur in a given
area only . Having a restricted range, these are easily
wiped out. Indonesia, the Philippines, China, India, and
Japan have the most endemic species of flora and fauna,
and these are seriously threatened.
MOUNTAIN VEGETATION
Mountain plant communities vary vertically because of cli-
matic change with elevation. This is known as altitudinal
zonation of vegetation. Everything from tropical to mixed
deciduous forests, to needle-leaf forests and grasslands ex-
ist with increases in altitude. Forested areas give way to
alpine meadows, stunted trees, and the tree line ,where
neither growing season nor soil depth will support tree life.
Here the sparse, stunted trees give way to the low-lying
flora, mosses, and lichens of subarctic tundra (Figure 2-18).
Even higher are barren rock and ice. As with other biomes,
population pressure is having deleterious impacts on
mountain environments, especially in the Himalayas.
Wealth ofWildlife Lost
The existence of two broad zoogeographical divisions—
Gondwanan and Laurasian—can be explained by plate
tectonics. About 15 million years ago, the continental
 
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