The Facts On File DICTIONARY of ECOLOGY and THE ENVIRONMENT The Facts On File DICTIONARY of ECOLOGY and THE ENVIRONMENT Edited by Jill Bailey ® The Facts On File Dictionary of Ecology and The Environment Copyright © 2004 by Market House Books Ltd 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: Facts On File, Inc. 132 West 31st Street New York NY 10001 Library of Congress Cataloging-in-Publication Data The Facts on File dictionary of ecology and the environment / edited by Jill Bailey. p. cm. Includes bibliographical references (p. ). ISBN 0-8160-4922-X (hc:alk. paper). 1. Ecology—Dictionaries. 2. Environmental sciences—Dictionaries. 1. Title: Dictionary of ecology and the environment. II. Bailey, Jill. III. Facts On File, Inc. QH540.4.F35 2003 577'.03—dc22 2003060353 Facts On File 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 Facts On File on the World Wide Web at http://www.factsonfile.com Compiled and typeset by Market House Books Ltd, Aylesbury, UK Printed in the United States of America MP 10 9 8 7 6 5 4 3 2 1 This book is printed on acid-free paper CONTENTS Preface vii Entries A to Z 1 Appendixes I. SI Units 246 II. Webpages 247 Bibliography 248 PREFACE This dictionary is one of a series covering the terminology and concepts used in important branches of science. The Facts on File Dictionary of Ecology and The Environment is planned as an additional source of information for students taking Advanced Placement (AP) Science courses in high schools. It will also be helpful to older students taking introductory college courses. This volume covers the topics important for an understanding of the basic principles of ecology - the scientific study of the relationships between or- ganisms and their natural environment. It also deals with the wider subject of how human populations interact with and affect the environment as a whole. Environmental science is an area of study involving a number of dif- ferent disciplines besides biology – chemistry, geology, meteorology, human geography, etc. There is particular interest in the effects of pollution and on conservation and the management of habitats. The definitions are intended to be clear and informative and, where possible, we have provided helpful diagrams and examples. The book also has a selection of short biographical entries for people who have made important contributions to ecology and environmental science. The appendixes contain a short list of useful web- pages and an informative bibliography. The book will be a helpful additional source of information for anyone studying the AP Environmental Science course, and also to students of AP Biology. However, we have not restricted the content to this syllabus. Ecol- ogy and the environment are important to everyone, and we have tried to cover these subjects in an interesting and informative way. ACKNOWLEDGMENTS Consultant editor Stewart Thompson B.Sc., Ph.D. Contributors John Clark B.Sc. Robert Hine B.Sc. Eve Daintith B.Sc. vii A abaptation The process by which evolu- quick subjective estimate. COVERand abun- tionary forces acting on ancestral forms dance may be combined for a subjective have helped determine present-day adapta- community description (see Braun-Blan- tions of organisms to their environment. quet scale). Quantitative measures of abundance include DENSITY(the number of abiotic Nonliving. Abiotic factors are individuals in a given area), cover, or the the physical and chemical aspects of an or- frequency of occurrence of a species in ran- ganism’s environment, such as light, tem- domly placed QUADRATS. perature, water, oxygen, and carbon dioxide. They include climatic, EDAPHIC abyssal zone The ocean-floor environ- and PHYSIOGRAPHIC factors. Compare bi- ment between 4000 and 6000 meters in otic. depth. It is characterized by extremely high water pressure, low temperatures and nu- abscission The controlled separation of trient levels, and an almost total absence of a part of an organism from the rest. For ex- light. See also benthic zone. ample, the shedding of leaves in the fall and the dropping of fruits is triggered by acclimation See acclimatization. changes in the balance of plant growth sub- stances (hormones). acclimatization A reversible change in the physiology or morphology of an organ- absolute humidity See humidity. ism in response to changes in its environ- ment. The term is generally used in the absorbed dose The amount of energy context of the natural environment. The absorbed by a tissue or other substance term acclimation tends to be used in a lab- from incident radiation. It is measured in oratory context. grays (Gy): one gray = the transfer of one joule of energy to one kilogram of material. acid A compound that acts as a proton donor in aqueous solution, i.e. it releases absorption 1. The retention of radiant hydrogen ions or protons, giving a pH less energy by an object, e.g. by the pigments of than 7. Acids turn litmus paper from blue a photosynthetic organism. to red, and react with alkalis (bases) to 2. The uptake of small nutrient molecules yield neutral salts. See pH. Compare alkali. into the body of an organism. In animals this takes place after digestion of larger acid rain Rain with a very low pH food molecules. In plants it includes the up- (below pH 5.6 and often below pH 4), due take of water and solutes. to pollution from oxides of nitrogen and 3. See adsorption. sulfur released by the burning of fossil fuels or other industrial emissions. These pollu- abundance A measure of the number of tants combine with water in the atmos- individual organisms in an area. An assess- phere, forming nitric and sulfuric acids, a ment of FREQUENCY(the relative abundance process that may be catalyzed by other pol- of each species present in an area), gives a lutants such as ammonia, hydrogen perox- 1