Transcript Document

Tropical Savannas and
Woodlands
Tropical savannas are grasslands with a
scattering of shrubs or trees.
Tropical woodlands have a higher
density of trees, but they do not form a
continuous canopy.
Tropical savanna and woodlands cover
about 20% of the earth’s land area, with
the largest concentration being found in
Africa.
Savanna locations are heavily
influenced by the Intertropical
Convergence Zone.
Seasonality of
rainfall helps
control savanna
distribution.
Native human populations
live largely by pastoralism.
The Serengeti-Mara ecosystem
contains the world’s greatest
concentration of large mammals.
The Serengeti illustrates many of the
relationships that are important in
ecosystems.
More than 3 million ungulates of
28 species inhabit the region.
These herbivores consume about 66% of
the aboveground net primary production.
Probably the largest fraction of any
ecosystem.
Areas subjected
to grazing show
primary
production about
twice that of
protected areas.
Grazing lawns.
Migrations follow a gradient of forage
abundance and nutritional quality.
Wildebeest, plains zebras, and Thomson’s
gazelles spend the wet part of the year on
the southern plains. As forage begins to dry
and disappear, they move northwest, then
gradually concentrate in the northern area
near the Kenyan border. When rains
resume, they return south to the plains.
Grazing by the migratory species is
complementary.
Zebras first, followed by wildebeest, and then
Thomson’s gazelles.
Many carnivores feed on the herbivores
Fragmentation of the savanna habitat is a
major threat to the wildlife of the region.
Perhaps the largest threat is poaching.
African black rhino
Javan rhino
Indian rhino
Sumatran
rhino
African white rhino
Distribution of the
Javan rhino