Grasslands (Biomes of the Earth)

270 Pages·2006·19.14 MB·english

by  Michael Allaby

BIOMES OF THE EARTH
GRASSLANDS
Michael Allaby
Illustrations by
Richard Garratt
Grasslands
Copyright © 2006 by Michael Allaby
All rights reserved. No part of this book may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying, recording, or by any information
storage or retrieval systems, without permission in writing from the publisher. For information
contact:
Chelsea House
An imprint of Infobase Publishing
132 West 31st Street
New York NY 10001
ISBN-13: 978-0-8160-5323-0
ISBN-10: 0-8160-5323-5
Library of Congress Cataloging-in-Publication Data
Allaby, Michael.
Grasslands / author, Michael Allaby ; illustrations by Richard Garratt.
p. cm.—(Biomes of the Earth)
Includes bibliographical references and index.
ISBN 0-8160-5323-5
1. Grassland ecology—Juvenile literature. 2. Grasslands—Juvenile literature. I. Garratt,
Richard, ill. II. Title. III. Series.
QH541.5.P7A38 2006
577.4—dc22 2005005615
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Text design by David Strelecky
Cover design by Cathy Rincon
Illustrations by Richard Garratt
Photo research by Elizabeth H. Oakes
Printed in Hong Kong
CP FOF 10 9 8 7 6 5 4 3 2
This book is printed on acid-free paper.
From Richard Garratt:
To Chantal, who has lightened my darkness.

CONTENTS
Preface ix
Acknowledgments xiii
Introduction: What are grasslands? xv
CHAPTER 1
GEOGRAPHY OF GRASSLANDS
1
Where grasslands occur 1
Temperate grasslands and tropical grasslands 3
Prairie 4
Steppe 7
Pampa 10
Veld 12
Tropical grasslands of South America 14
Savanna 17
Australian grasslands 20
Upland grasslands 22
CHAPTER 2
GEOLOGY OF GRASSLANDS
26
Movement of continents 26
Alfred Lothar Wegener and continental drift 28
How mountains rise and wear away 31
Grassland soils 37
How soils are classified 39
Laterite 40
Water and grasslands 41
CHAPTER 3
GRASSLAND CLIMATES
45
Why there are seasons 45
Continental and maritime climates 48
How climates are classified 49
Dry seasons and rainy seasons 51
The Dust Bowl 55
Monsoons 57
Adiabatic cooling and warming 59
El Niño 61
Convection and storms 64
Lapse rates and stability 66
Tornadoes 67
CHAPTER 4
HISTORY OF GRASSLANDS
71
Evolution of grasslands 71
Grasslands and past climate changes 73
How forest can change into grassland 76
The transformation of New Zealand 78
CHAPTER 5
LIFE ON THE GRASSLANDS
81
What is grass? 81
How grasses work 84
Photosynthesis 85
Prairie grasses 89
Pampas grasses 92
Steppe grasses 94
Savanna grasses 95
Grassland trees and shrubs 99
Grassland herbs 100
Grassland insects 103
Mongooses, prairie dogs, marmots, ground
squirrels, and pocket gophers 110
Snakes and lizards 114
Grazing animals 119
Hunters of the grasslands 124
Hunter and prey: The evolutionary arms race 130
Grassland birds 130
Coping with drought 136
Coping with heat and cold 139
Hibernation 141
CHAPTER 6
GRASSLAND ECOLOGY
143
How the plant eaters help the grass 143
Food chains and food webs 144
Ecological pyramids 147
Do predators control their prey? 151
How herding provides safety in numbers 153
Mammal migrations 155
CHAPTER 7
PEOPLES OF THE GRASSLANDS
158
Peoples of the prairie 158
Homesteaders and the way the prairie was
transformed 160
Indians and gauchos: The peoples of the pampa 165
Farmers of the pampa 167
Peoples of the African savanna 169
Traditional life on the steppe of Central Asia 171
Genghis Khan, the Golden Horde, and
Mogul emperors 173
Aboriginal peoples of the Australian grasslands 177
CHAPTER 8
USES FOR GRASSLAND
179
Cereal farming 179
The origin of cereals 180
Cattle ranching 182
The origin of cattle 184
Sheep farms of Australia and New Zealand 186
The origin of sheep 189
Upland sheep farming 190
Forestry 191
Biofuel production 194
Biofuels and the greenhouse effect 195
CHAPTER 9
BIODIVERSITY AND GRASSLANDS
198
What is biodiversity? 198
Why it matters 199
Protecting grassland species 201
The Biodiversity Convention 202
CHAPTER 10
THREATS TO GRASSLAND
205
Conversion to farmland 205
Conversion to forest 207
Overgrazing and soil erosion 209
Climate change 211
The greenhouse effect 212
Expansion of towns and roads 214
CHAPTER 11
MANAGING THE GRASSLANDS
218
Lessons from the Dust Bowl 218
Ranching on equatorial grasslands 220
Farming tropical grasslands 222
Dry farming 224
Grassland restoration and conservation 225
CONCLUSION
228
What future for the grasslands? 228
SI units and conversions 231
Soil classification: Orders of the soil taxonomy 235
Glossary 239
Bibliography and further reading 253
Index 257
PREFACE
Earth is a remarkable planet. There is nowhere else in our
solar system where life can survive in such a great diversity of
forms. As far as we can currently tell, our planet is unique.
Isolated in the barren emptiness of space, here on Earth we
are surrounded by a remarkable range of living things, from
the bacteria that inhabit the soil to the great whales that
migrate through the oceans, from the giant redwood trees of
the Pacific forests to the mosses that grow on urban side-
walks. In a desolate universe, Earth teems with life in a bewil-
dering variety of forms.
One of the most exciting things about the Earth is the rich
pattern of plant and animal communities that exists over its
surface. The hot, wet conditions of the equatorial regions
support dense rain forests with tall canopies occupied by a
wealth of animals, some of which may never touch the
ground. The cold, bleak conditions of the polar regions, on
the other hand, sustain a much lower variety of species of
plants and animals, but those that do survive under such
harsh conditions have remarkable adaptations to their test-
ing environment. Between these two extremes lie many
other types of complex communities, each well suited to the
particular conditions of climate prevailing in its region.
Scientists call these communities biomes.
The different biomes of the world have much in common
with one another. Each has a plant component, which is
responsible for trapping the energy of the Sun and making it
available to the other members of the community. Each has
grazing animals, both large and small, that take advantage of
the store of energy found within the bodies of plants. Then
come the predators, ranging from tiny spiders that feed upon
even smaller insects to tigers, eagles, and polar bears that sur-
vive by preying upon large animals. All of these living things
IX