Biomes of the earth grasslands

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 Grassland ecology—Juvenile literature Grasslands—Juvenile literature I Garratt, Richard, ill II Title III Series QH541.5.P7A38 2006 577.4—dc22 2005005615 Chelsea House books are available at special discounts when purchased in bulk quantities for businesses, associations, institutions, or sales promotions Please call our Special Sales Department in New York at (212) 967-8800 or (800) 322-8755 You can find Chelsea House on the World Wide Web at http://www.chelseahouse.com 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 This book is printed on acid-free paper From Richard Garratt: To Chantal, who has lightened my darkness CONTENTS Preface Acknowledgments Introduction: What are grasslands? ix xiii xv CHAPTER GEOGRAPHY OF GRASSLANDS Where grasslands occur Temperate grasslands and tropical grasslands Prairie Steppe Pampa Veld Tropical grasslands of South America Savanna Australian grasslands Upland grasslands 1 10 12 14 17 20 22 CHAPTER GEOLOGY OF GRASSLANDS Movement of continents Alfred Lothar Wegener and continental drift How mountains rise and wear away Grassland soils How soils are classified Laterite Water and grasslands 26 26 28 31 37 39 40 41 CHAPTER GRASSLAND CLIMATES Why there are seasons Continental and maritime climates How climates are classified 45 45 48 49 Dry seasons and rainy seasons The Dust Bowl Monsoons Adiabatic cooling and warming El Niño Convection and storms Lapse rates and stability Tornadoes 51 55 57 59 61 64 66 67 CHAPTER HISTORY OF GRASSLANDS Evolution of grasslands Grasslands and past climate changes How forest can change into grassland The transformation of New Zealand 71 71 73 76 78 CHAPTER LIFE ON THE GRASSLANDS What is grass? How grasses work 81 81 84 Photosynthesis 85 Prairie grasses Pampas grasses Steppe grasses Savanna grasses Grassland trees and shrubs Grassland herbs Grassland insects Mongooses, prairie dogs, marmots, ground squirrels, and pocket gophers Snakes and lizards Grazing animals Hunters of the grasslands 89 92 94 95 99 100 103 Hunter and prey: The evolutionary arms race 130 Grassland birds Coping with drought Coping with heat and cold Hibernation 110 114 119 124 130 136 139 141 CHAPTER GRASSLAND ECOLOGY How the plant eaters help the grass Food chains and food webs Ecological pyramids Do predators control their prey? How herding provides safety in numbers Mammal migrations 143 143 144 147 151 153 155 CHAPTER PEOPLES OF THE GRASSLANDS Peoples of the prairie Homesteaders and the way the prairie was transformed Indians and gauchos: The peoples of the pampa Farmers of the pampa Peoples of the African savanna Traditional life on the steppe of Central Asia Genghis Khan, the Golden Horde, and Mogul emperors Aboriginal peoples of the Australian grasslands 158 158 160 165 167 169 171 173 177 CHAPTER USES FOR GRASSLAND Cereal farming The origin of cereals Cattle ranching The origin of cattle Sheep farms of Australia and New Zealand The origin of sheep Upland sheep farming Forestry Biofuel production Biofuels and the greenhouse effect 179 179 180 182 184 186 189 190 191 194 195 CHAPTER BIODIVERSITY AND GRASSLANDS What is biodiversity? 198 198 Why it matters Protecting grassland species 199 201 The Biodiversity Convention 202 CHAPTER 10 THREATS TO GRASSLAND Conversion to farmland Conversion to forest Overgrazing and soil erosion Climate change The greenhouse effect Expansion of towns and roads 205 205 207 209 211 212 214 CHAPTER 11 MANAGING THE GRASSLANDS Lessons from the Dust Bowl Ranching on equatorial grasslands Farming tropical grasslands Dry farming 218 218 220 222 224 Grassland restoration and conservation 225 CONCLUSION What future for the grasslands? 228 228 SI units and conversions Soil classification: Orders of the soil taxonomy Glossary Bibliography and further reading Index 231 235 239 253 257 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 sidewalks In a desolate universe, Earth teems with life in a bewildering 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 survive under such harsh conditions have remarkable adaptations to their testing 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 survive by preying upon large animals All of these living things IX ... CHAPTER PEOPLES OF THE GRASSLANDS Peoples of the prairie Homesteaders and the way the prairie was transformed Indians and gauchos: The peoples of the pampa Farmers of the pampa Peoples of the African... covers all of Lesotho and part of Swaziland The map shows the area and location of the South African veld The largest area, called the Highveld, covers most of the Free State To the north of the Highveld... existence, these sediments slide down the submerged sloping edges of the continents until they cover every part of the ocean floor Gradually the weight of the upper layers of sediments compresses the