RESOURCES FOR THE FUTURE, INC. 1755 Massachusetts Avenue, N.W., Washington, D.C. 20036

Board of Directors: Erwin D. Canham, Chairman, Robert O. Anderson, Harrison Brown, Edward J. Cleary, Joseph L. Fisher, Luther H. Foster, F. Kenneth Hare, Charles J. Hitch, Charles F. Luce, Frank Pace, Jr., Emanuel R. Piore, Stanley H. Ruttenberg, Lauren K. Soth, Maurice F. Strong, Mrs. Robert J. Stuart, P. F. Watzek, Gilbert F. White. Honorary Directors: Horace M. Albright, Reuben G. Gustavson, Hugh L. Keenleyside, Edward S. Mason, William S. Paley, Laurance S. Rockefeller, John W. Vanderwilt.

President: Joseph L. Fisher Secretary-Treasurer: John E. Herbert

Resources for the Future is a nonprofit corporation for research and education in the development, conservation, and use of natural resources and the improvement of the quality of the environment. It was established in 1952 with the cooperation of the Ford Foundation. Part of the work of Resources for the Future is carried out by its resident staff; part is supported by grants to universities and other nonprofit organizations. Unless otherwise stated, interpretations and conclusions in RFF publications are those of the authors; the organization takes responsibility for the selection of significant subjects for study, the competence of the researchers, and their freedom of inquiry.

These papers are part of the RFF natural environments program, which is directed by John V. Krutilla.

RFF editors: Mark Reinsberg, Vera W. Dodds, Nora E. Roots, Tadd Fisher.

Copyright © 1972 by Resources for the Future, Inc. All rights reserved Manufactured in the United States of America

The Johns Hopkins University Press, Baltimore, Maryland 21218 The Johns Hopkins University Press Ltd., London

Library of Congress Catalog Card Number 72-4441 ISBN 0-8018-1446-4

Library of Congress Cataloging in Publication data will be found on the last printed page of this book.

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