Visualizing Environmental Science

Average monthly precipitation in cm

14

16

18

20

22

12

10

8

6

4

2

0

Months

16

20

24

12

8

4

0

Average monthly temperature in

°C

JFMAMJJASOND

© DLILLC/Corbis

Based on data from http://www.worldclimate.com

African savanna ( Figure 6.11). Large preda-

tors, such as lions and hyenas, kill and scav-

enge the herds. In areas of seasonally varying

rainfall, the herds and their predators may

migrate annually.

Savanna in many places is being converted into

rangeland for cattle and other domesticated animals.

The problem is particularly serious in Africa, where

human populations are growing rapidly.

Tropical Rain Forest

Tropical rain forest occurs

where temperatures are warm

throughout the year and pre-

cipitation occurs almost daily.

The annual precipitation in a

tropical rain forest is typically between 200 and 450 cm

(80 to 180 in). A related biome not described here is

the tropical dry forest, where temperatures are also warm

Savanna

Savanna, a tropical grassland, is found in areas
of low rainfall or intense seasonal rainfall with
prolonged dry periods. Temperatures in savan-
nas vary little throughout the year. Precipita-
tion is the overriding climate factor: Annual precipitation
is 85 to 150 cm (34 to 60 in). Savanna soil is somewhat low
in essential nutrient minerals, in part because it is heav-
ily leached during rainy periods—that is, nutrient miner-
als filter out of the topsoil. Although the African savanna
is best known, savanna also occurs in South America,
western India, and northern Australia.
Savanna has wide expanses of grasses interrupted by
occasional trees like the acacia, which bristles with thorns
to provide protection against herbivores (see Figure
5.17b). Both trees and grasses have fire-adapted features,
such as extensive underground root systems, that enable
them to survive seasonal droughts as well as periodic fires.
Spectacular herds of herbivores such as antelope,
giraffe, elephants, wildebeest, and zebra occur in the

savanna A tropical

grassland with widely

scattered trees or

clumps of trees.

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Tropical grasslands such as this one, with widely scattered acacia trees, support large herds
of grazing animals and their predators. Photographed in Kilimanjaro National Park, Tanzania,
with Mount Kilimanjaro in the background. Climate graph shows monthly temperatures and
precipitation for Lusaka, Zambia.

tropical rain forest

A lush, species-rich

forest biome that

occurs where the

climate is warm and

moist throughout

the year.

Interpreting Data

In terms of ranges shown across the

year, does the pattern of average

monthly precipitation differ from

the pattern of average monthly

temperature in this savanna? Use

data to support your answer.