Page 17 - The World About Us

Okavango
2.1.2
1.1.1

What is the flora and fauna of the tropical grasslands?

The vegeta on of the tropical
grasslands (also known as savannah) is,
as the name suggests, dominated by
grasses. These plants have evolved to be
able to cope well with the dry season
and grow rapidly when the rains return.
In the rainforests there are a great
variety of trees and in the grasslands a
wide variety of grasses have evolved.
There are 750 species of grasses in the
Serenge Na onal Park alone. Grasses
have evolved to become either annuals
or perennials.
The annual grasses germinate from
seed, grow, flower, set seed and die in a
single season. They grow rapidly and
produce large numbers of seeds to
ensure their survival. Perennial grasses
die back during the dry season but store
their nutrients in a root system ready to fig.41 Wildebeest and zebra on the Serenge plains of Tanzania.
spring into life again when the first rains
arrive. Like annuals they can be very fast during the dry season, when the herds
are elsewhere, life is tough for these
growing with Miscanthus elephant grass
territorial animals and many young will
growing several metres in just a few
weeks. die of hunger in their first year.
The wide variety of grasses have
encouraged vast herds of large, grazing
animals including, in Africa, wildebeest,
zebra, buffalo and gazelle. These animals
migrate to follow the rains, which always
ensures a fresh supply of young fig.42 Acacia: fire and drought tolerant.
nutri ous grass to eat. Other migratory role of grazing mammals, consuming
animals arrive at the end of the rainy
vast quan es of grass.
season. Huge flocks of red-billed quelea,
Where there are trees, such as the
the locust bird, arrive as the grass seeds
ripen at the end of the rains. In South acacia and baobab, these species have
America, where there are no large, evolved drought tolerant (xerophy c) fig.44 Seed-ea ng quelea appear in flocks
and fire-tolerant (pyrophy c)
grazing animals, termites have taken the so vast they are known as the locust bird.
adapta ons to cope with life in the
fig.43 Giraffe feed on small but grasslands. Acacia has deep roots to
nutri ous acacia leaves. reach underground water, ny leaves KEY TERMS
with sunken stomata to reduce moisture
loss and a thick, fire-retardant bark. Temperate regions: Geographical
region lying between the Tropic of
As the acacia is evergreen, its leaves Cancer and Arctic Circle and the Tropic
are prized by grazing animals such as
of Capricorn and the Antarctic Circle.
giraffe and elephants. It is thought that
the elephants, with their ability to knock Tropical region: Geographical and
over trees and consume vast quan es climatic region found between 23 /
north and south of the Equator.
of acacia saplings, help keep the
grasslands clear of acacia scrub Wet and dry (savannah) regions:
woodland. Located between the Equatorial
rainforests and the hot deserts to the
Predators, such as lions and cheetah,
may have an easy me when the large north and south, this region is a
transitional biome with rainfall varying
herds pass through their territories but,
between 500 and 1,500mm each year.

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Ecosystems have distinct distributions and characteristics.