Table Of ContentENVIRONMENTAL SCIENCES AND APPLICATIONS
Other titles in the series:
Volume 1 UNITED NATIONS Desertification: Its Causes and Consequenses
Volume 2 FUKUSHIMA, Y. Science for Better Environment
Volume 3 UNITED NATIONS Alternative Strategies for Desert
INSTITUTE FOR Development and Management
TRAINING AND
RESEARCH
Volume 4 BISWAS, A. K. A Strategy for the Ozone Layer
Volume 5 HUSAR, R. B., et al. Sulfur in the Atmosphere
Volume 6 J0RGENSEN, S. E. Handbook of Environmental Data and
Ecological Parameters
STATE-OF-THE-ART IN
ECOLOGICAL MODELLING
Proceedings of the Conference on
Ecological Modelling, Copenhagen, Denmark
28 August - 2 September 1978
Editor
S. E. J0RGENSEN
International Society for Ecological Modelling
Distributed throughout the world for the
INTERNATIONAL SOCIETY FOR
ECOLOGICAL MODELLING
by
PERGAMON PRESS
OXFORD NEW YORK TORONTO SYDNEY · PARIS FRANKFURT
U.K. Pergamon Press Ltd., Headington Hill Hall,
Oxford OX3 OBW. England
U.S.A. Pergamon Press Inc., Maxwell House, Fairview Park,
Elmsford, New York 10523, U.S.A.
CANADA Pergamon of Canada, Suite 104, 150 Consumers Road,
Willowdale, Ontario M2J.1P9, Canada
AUSTRALIA Pergamon Press (Aust.) Pty. Ltd., P.O. Box 544,
Potts Point, N.S.W. 2011, Australia!
FRANCE Pergamon Press SARL, 24 rue des Ecoles,
75240 Paris, Cedex 05, France
FEDERAL REPUBLIC Pergamon Press GmbH, 6242 Kronberg Taunus,
OF GERMANY Pferdstrasse 1, Federal Republic of Germany
Copyright © 1979 International Society for Ecological Modelling.
All Rights Reserved. No part of this publication may be
reproduced, stored in a retrieval system or transmitted in
any form or by any means: electronic, electrostatic,
magnetic tape, mechanical, photocopying, recording or
otherwise, without permission in writing from the
copyright holders.
First edition 1979
British Library Cataloguing in Publication Data
Conference on Ecological Modelling, Copenhagen, 1978
State-of-the-art in ecological modelling. -
(Environmental sciences and applications; vol. 7).
1. Ecology - Mathematical models - Congresses.
I. Title. II. Jorgensen, S. E. III. International
Society of Ecological Modelling. IV. Series
574.5ΌΓ84 QH 541.5.M3 78-41208
ISBN 0-08-023443-7
Preface
28. August-2. September 1.978 was in Copenhagen held ISEM!s
1st International Conference on the S tate-of-the-Art in Ecologi-
gal Modelling.
The proceedings contain staie-of-the-art or review papers, ori-
ginal papers and the result of a working session from this confe-
rence ·
The first part of the book containing the invited state-of-
the-art or review presentations, covers the following topics
within the field of ecological modelling: river models, appli-
cation of graphical methods, application of microcosms in ecolo-
gical modelling, prey-predator models, modelling water quality
and irrigation in agriculture, modelling the distribution and ef-
fect of toxic substances, lake models.
The second part consists of 29 original papers presented on
the conference. The following topics were touched:
1. Models of Sea and Coastal Areas (3 papers)
2. Modelling the Atmospheric Pollution (l paper)
3· Modelling Ecosystems in the Lithosphθre (l paper)
4. Water Management Models (k papers)
5· Lake Models (6 papers)
6. Primary Production Models (3 papers)
7. Prey-Predator Models (2 papers)
8. Theoretical-mathematica1 Problems (9 papers)
A working session was arranged for discussion of the state-of-
the-art and the needs for further research within some selected
fields of ecological modelling. During the working session, the
participants were discussing these problems in small groups. The
proceedings summarizes the conclusions, covering the following
i terns :
Prey-Predator Models
Lake and River Models
Application of Microcosms
Toxic Substances Models
Hydrochemical Modelling of Irrigated Agriculture
Modelling Sediment-Water Interaction
Plankton Models
Holistic Approaches to Ecological Modelling
State-of-the-Art in Ecological Modelling. Vol. 7.
INTERNATIONAL SOCIETY FOR ECOLOGICAL
MODELLING AN INTRODUCTION
Asit K. Biswas, President, International Society for Ecological Modelling.
I would like to take this opportunity to explain to you why
this new International Society for Ecological Modelling has been
formed, what are its objectives, and what we plan to achieve in the
future.
We are now living in an era of dramatic changes. It is of
course true that the world scenarios have never been static ever
since the first form of life appeared on earth. The present life-
forms have developed through a continuous evolutionary process, and
there is no reason to believe that this process has come to an end
and that man is the ultimate animal that has evolved and is here to
stay until perpetuity. There is no doubt that mismanagement by man
of the environment and various ecosystems, on which ultimately our
life-support systems depend, can hasten our own demise from this
earth.
It is true that the world we live in is dynamic, and events and
factors are continually changing with time. For example, world
population has been increasing continuously ever since man first
appeared on the scene. But the real problem is not so much that
2
everything in this world has been dynamic since time immemorial,
as it is the rate and/or magnitude of the changes that have taken
place in the twentieth century. Let us consider the scale of the
changes we are witnessing or have witnessed in the present century:
It took nearly a million years for the first billion
people to appear on earth, but the next billion is due
in only another 15 years.
From the beginning of our civilization to the end of the
Second World War all the world1s industry totaled less than
the new industrialized capacity that has been produced with-
in the last 3 years.
The United States alone used more resources in one decade,
1959 to 1968, than did the whole world in all previous
history.
A century ago, the production of crude petroleum was
negligible. By 1966, the production amounted to 1,641
million metric tons per year, having increased sixfold over
the preceding 30 years. It has increased significantly more
since 1966.
The world will consume more metals during the next 3 5 years
than it has in the last 2,000.
The increase in population and standard of living has meant
that we need more food, fibre, raw materials, energy and other
resources to sustain human needs. It has also resulted in the
generation of increasing volumes of residuals which have to be
ultimately disposed of on our land, water and atmosphere in such
a fashion so as to create minimum ecological damages. Furthermore,
man's economic activities have seldom been uniformly distributed all
over the world: they are being increasingly concentrated in a few
urban centres. Accelerated urbanization that we are witnessing
at present, as we approach the twenty-first century, means that
3
ecosystems in those select urban centres are now under continually
increasing pressure which directly stem from human activities. In
many cases we have already reached the point of no return, where
we have already made irrepairable damages to our environment.
Environment in such instances can no longer assimilate the insults:
its resiliency has virtually disappeared.
Fortunately for the future of man we are aware of some of
these problems which we ourselves have created, and there are some
indications that we are attempting to change our behaviour. Thus,
within the last decade, in many countries, societal values and
norms have changed significantly from an automatic acceptance
of economic growth for its own sake to a deeper concern and better
understanding of the ecological and social implications of such
growths. This new orientation of our philosophy is manifested in
our search for "alternate styles of development," "ecodevelopment,"
"new growth," "conserver society," and a host of other similar
concepts. This shift in our value system has also begun to
permeate the political process, within which most major decisions
are taken, and this concern is gradually being reflected in national
and international policies.
These developments, positive as though they are, have
contributed to the further complexification of the planning and
decision-making processes, which were not simple to begin with.
Even though these processes have become exceedingly complex at
present, and will undoubtedly continue to become more complex in
the future, it is becoming increasingly evident that the average
planner and decision-maker has been provided with very few
h
fundamentally new tools and concepts in the past several decades
to cope with such complexities. One of these few new tools is
modelling.
The state-of-the-art ecological modelling haö advanced
considerably during the past decade. Our knowledge and understanding
of ecosystems have improved, and accordingly we are now in a
better position to develop ecological models which can be used for
operational purposes. It has added a new dimension to our analytical
capabilities. Furthermore developments in computer technology during
the past two decades have not only reduced the cost of unit operation
but also have significantly increased computational capabilities.
For example, in 19 52, it cost $1.26 to carry out 100,000 multi-
plications. This unit cost has progressively declined to $0.26
by 1958, $0.12 by 1964, and $0.05 by 1970. Today the same
computations can be carried out for less than one cent and within
a fraction of the time that was necessary to carry out such an
operation in 19 52. Hence, the potential benefits of ecological
modelling is enormous: we have so far hardly even scratched the
surface.
Because of this situation many like-minded scientists and policy
makers felt the need to form a new society for ecological modellers,
where we can discuss the latest developments and applications
thereof, research priorities, and training programmes. We also
urgently need a forum for information exchange. No longer is it
possible to search through thousands of journals hoping one would
find some relevant articles on ecological modelling. Globally
there are now some 35,000 journals which publish about 2,000,000
articles each year, written by about 750,000 scientists in some
5
50 languages. The situation had clearly become intolerable.
The existence of this sad state of affairs has led to the
formation of the International Society for Ecological Modelling,
popularly known as ISEM. Our main objective is to facilitate
the international exchange of ideas and concepts, scientific results,
and pertinent knowledge, as well as the application thereof, within
the general area of ecological and environmental modelling.
ISEM is an interdisciplinary society, and we intend to
emphasize this aspect continually. An implicit assumption of many
university departments and professions is that branches of science
are often interpreted as reality. In other words, it is assumed
that nature is organized in the same way as the professions are.
Thus, we talk of engineering problems, biological problems, social
problems, chemical problems, medical problems, etc. In a real
world, of course, nothing can be further from the truth. A problem
is a problem, and the addition of the professional adjective only
indicates our ways of viewing and analysing the problem. The
method of analysis depends on our training and background, and this
very often introduces significant biases in the resulting analyses.
Individuals trained in different disciplines often look at
a common problem to be analyzed and solved in totally different
fashions, depending on their education, background, and experience.
The point can be best illustrated by the following story. The
manager of an old building once received complaints from his
tenants regarding the long waiting time for elevators, whereupon
he called in his engineers and asked for possible solutions.
The engineers suggested three alternatives: add extra elevators,
replace old elevators with more efficient new ones, or use a banking
6
system, that is one elevator serving a specific set of floors.
The manager rejected the first two because they were too expensive
for an old building and thus they were not economical. The third
alternative reduced the waiting time only marginally, and hence
was not an acceptable solution. The manager, however, had a friend
who was a psychologist and who heard of this dilemma. The psy-
chologist offered a simple but economic solution: install mirrors
in the elevator lobbies. This simple solution surprisingly enough
stopped all the complaints. The mirror gave the ladies waiting
for the elevator an opportunity to do some adjustments, and the men
could look at the ladies in the mirror without any embarrassment 1
Whether the story is true or not is really unimportant: what
is important is the fact that the psychologist saw the same problem
that was facing the engineers in an entirely different light. The
engineers attempted to reduce the actual waiting time by technological
means, but that solution did not occur to the psychologist. His
solution was not to reduce the waiting time but to make it look like
it had been reduced, and this happened to be an acceptable solution
in this particular case. The point I am trying to make is that an
interdisciplinary group is an absolute necessity for ecological
modelling because different disciplines could perceive the same
problem in different lights as a result of their training and
background. Thus, ISEM plans to be truly interdisciplinary society,
and I am happy to report that we have already attracted scientists
from various disciplines.
ISEM will emphasize research, application of research results
and training. We believe that research by itself is a valid objective
to expand our frontiers of knowledge. Simultaneously we would also
