Table Of ContentContributors
LEWIS J. BLEDSOE
NORMAN R. GLASS
DON W. HAYNE
STEPHEN P. HUBBELL
NORMAN E. KOWAL
NANCY T. KUENZEL
RAY R. LASSITER
ROBERT V. O'NEILL
BERNARD C. PATTEN
EDWARD J. RYKIEL, JR.
GEORGE M. VAN DYNE
F. M. WILLIAMS
RICHARD B. WILLIAMS
SYSTEMS ANALYSIS AND
SIMULATION IN ECOLOGY
Edited by BERNARD C. PATTEN
Department of Zoology
University of Georgia
Athens, Georgia
VOLUME I
ACADEMIC PRESS New York and London 1971
COPYRIGHT © 1971, BY ACADEMIC PRESS, INC.
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AT RUTGERS
List of Contributors
Numbers in parentheses indicate the pages on which the authors* contributions begin.
LEWIS J. BLEDSOE, College of Forestry and Natural Resources, Colorado
State University, Fort Collins, Colorado (479)
NORMAN R. GLASS, Institute of Ecology, Environmental Systems Group,
University of California, Davis, California (325)
DON W. HAYNE, Department of Experimental Statistics, North Carolina
State University, Raleigh, North Carolina (367)
STEPHEN P. HUBBELL,* Department of Zoology, University of California,
Berkeley, California (269)
NORMAN E. KOWAL,+ Department of Entomology and Institute of
Ecology, University of Georgia, Athens, Georgia (123)
NANCY T. KUENZEL, Institute of Ecology and Department of Zoology,
University of Georgia, Athens, Georgia (513)
RAY R. LASSITER, Environmental Protection Agency, U. S. Federal Water
Quality Office, Southeast Water Laboratory, Athens, Georgia (367)
ROBERT V. O'NEILL, Ecological Sciences Division, Oak Ridge National
Laboratory, Oak Ridge, Tennessee (441)
BERNARD C. PATTEN, Department of Zoology and Institute of Ecology,
University of Georgia, Athens, Georgia (3)
* Present address: Department of Zoology, University of Michigan, Ann Arbor,
Michigan.
+ Present address: Department of Biology, West Virginia University, Morgantown,
West Virginia.
xi
Xll LIST OF CONTRIBUTORS
EDWARD J. RYKIEL, JR., Institute of Ecology and Department of Zoology,
University of Georgia, Athens, Georgia (513)
GEORGE M. VAN DYNE, College of Forestry and Natural Resources,
Colorado State University, Fort Collins, Colorado (479)
F. M. WILLIAMS,* Department of Zoology, University of Minnesota,
Minneapolis, Minnesota (197)
RICHARD B. WILLIAMS, Bureau of Commercial Fisheries, Center for
Estuarine and Menhaden Research, Beaufort, North Carolina (543)
* Present address: Department of Biology, The Pennsylvania State University, Univer-
sity Park, Pennsylvania.
Preface
This is a book of ecology in transition from a "soft" science, synecology,
to a "hard" science, systems ecology, in which the lens of H. T. Odum's
"macroscope'^on the world of big patterns is the machinery of mathe-
matical modeling, simulation and systems analysis. The book is sub-
stantially the creation of young people at a time when youth in America
is experimenting with, if not revising and reorganizing, the ethical
and moral basis of contemporary civilized life. The systems theme is
central in this exploration in its two salient aspects, change and relation-
ship, and its current pervasiveness in science as well as in society seems
no accident as the world presses closer together in the last third of the
Twentieth Century.
Soft ecology of the past2 has identified in nature a hierarchy of organism/
environment units, each maintaining structural and functional identity
while evolving in the large and fluxing constituents in the small. Such
a conception is quintessentially an organismic one, with philosophical
overtones that have led recently to an eruption of public concern
about the fate and well-being of the planetary "organism" in the face
of human extravagance. This book is an enthusiastic and optimistic
statement about the fundamental adaptability of the scientific mechanism
to newly appreciated truths of existence. It documents, in ecological
science, a move away from the explanatory or cognitive criterion of
truth, a soft criterion which heuristically lends intellectual points of
leverage for seeking understanding, and toward the predictive criterion,
a hard one with the potential of leading ultimately to optimal design
and control of ecosystems.
1 Odum, H. T. (1971). "Environment, Power and Society." Wiley (Interscience),
New York.
2 The terminology is that of Rapoport, A. (1970). Genl. Syst. Yrbk. 15, 15.
xiii
XIV PREFACE
Systems ecology, in its infancy, is a "bisociation"3, a hybrid intersection
of two branches of science, biology and engineering, previously discon-
nected. Such a juxtaposition is not new to biology, recalling earlier asso-
ciations with exact sciences like chemistry and physics that proved so
potent in the microscopic concerns about organisms, and indeed, that
became the dominant biology of recent years. This new bond comes
fortuitously, or perhaps providentially, at a time of winding down of
technology in the human appreciative system, with concommitant release
from productive work of skilled engineers trained in the hard aspects of
systems. Ecologists need only open the door ever so slightly and one can
easily forecast a shotgun marriage in only a few years, and an explosive
development of the predictive potential. Indeed, it has already begun to
happen. Take, as a single example from many indications, the statement
last April by Frank C. Rieman, President of SCi (Simulation Councils,
Inc.), redirecting the purposes of that entire engineering society:
. . . SCi has its roots in analog computation in the aerospace
industry, from which it grew naturally into the field of hybrid
computation. This history dominates the society's image
today. The Executive Committee feels that it is now time to
change that image. . . . We would like to direct the effort of
the Society toward mathematical modeling and specific
applications, independent of computational technique, rather
than the analog/hybrid hardware orientation we now seem to
have. . . . The Executive Committee is recommending that
the attention of SCi, as a society, be directed toward solution
of problems in the environmental and ecological areas.
This book, written in the language of systems scientists, should help
accelerate development of an inevitable kinship between them and
ecologists by demonstrating multifariously how ecology can be cast in
their terms.
I take particular pleasure in having the work of a number of my
students on exhibit here. Students have been the mainspring of my
development as a systems ecologist, and they continue to challenge and
question the many tentative and half-baked notions that seem to be
integral in the learning process. All my students, including those not
represented in these pages, deserve special recognition for the unique
and significant role they have played and continue to play in this chal-
lenging enterprise.
3 Kestin, J. (1970). Am. Scient. 58, 250.
PREFACE XV
There are also debts to the past and I discharge, in a small way on
the dedication page, the two of profoundest meaning to me. These two
men taught and practiced ecology that was of a kind whose kernel
should be conserved wherever this field leads from here. It was an
ecology of interrelationships that did not fail to look closely and inti-
mately at the players. It was a field ecology, a natural history ecology,
but profoundly an ecology of systems.
Throughout this project my wife, Marie, encouraged and prodded and
absorbed externalities at home. Thelma Richardson aided in various
programming and editorial chores, particularly in the final stages. And
Bill Cosgrove, my department chairman, provided an outstanding climate
for unencumbered academic pursuits at the University of Georgia. For
these assistances, I am grateful. But the book belongs to the authors,
and I would like especially to aknowledge and congratulate them all for
their roles in bringing it to fruition.
Athens, Georgia BERNARD C. PATTEN
January, 1971
PART I
INTRODUCTION TO MODELING
A science is known by its methods, and ecology as "the painful elaboration of the obvious*'
has for a long time followed the questionable path of seeking insights by pushing numbers
around. "Quantify and clarify" has been the paradigm of much contemporary study, and
the illusion of synecology as a "hard" science has been provided by widespread use and
misuse of statistical methods, which have enormous predictive appeal if little explanatory
power.
Systems ecology does not lean heavily upon numbers until the latter stages of an investiga-
tion. It differs from statistical ecology in its greater emphasis on the explanatory criterion
of truth as applied to holistic behavior. It accepts as an operating principle that no complex
system can be fully known in all of its interactive details, and accordingly seeks to elucidate
global properties that characterize "core" dynamics, the broad set of possibilities from
which actual behavior is generated according to environmental inputs. The current method
of systems ecology is mathematical modeling, for the dual and distinct purposes of simulation
and systems analysis. This section provides an overview of some of the methods and rationales
for ecological systems modeling in relation to these purposes.
Chapter 1 is an elementary introduction to the use of analog and digital computers for
simulation. The presentation is tutorial, designed to bring the reader with modest mathe-
matical preparation quickly to the point of being able to use modern computing machines
effectively. In a sense the treatment is selective and superficial, sparing many details, but
it offers the proven advantage of giving a fast return in satisfaction to the new student of
simulation. The methods selected, and how they are presented, are the result of a number
of years of classroom sifting and sorting. The treatment centers on compartment models
and their expression by means of ordinary differential equations.
Analog computation is covered first, as the surest way to captivate a new audience.With
a variety of graphic outputs available, and instantaneous turnaround time, there is no better
approach to developing a subjective appreciation for what holism is all about in connection
with system dynamics. At the turn of a potentiometer dial an individual can alter system
inputs, outputs, or internal connections, and observe immediately the behavioral conse-
quences, or lack of them, of his act. Fortran programming, only as much as necessary, is
introduced next and, with a presentation of numerical approximation methods, the reader
is encouraged by examples and exercises to retrace the same ground on the digital computer
that he has just covered with the analog. Thus gaining familiarity with some of the undesirable
as well as desirable features of simulation by Fortran, the instruction loop is closed by
introducing one of the modern simulation languages, S/360 CSMP. This language essentially
makes an analog computer of the digital machine, except for turnaround, and so simple is
its use that it could well have been introduced first were it not for the pedagogical ad-
vantages of the preceding analog and Fortran struggles. A reader who masters this chapter
is well on his way to effective computer use as a basis for his further progress in systems
ecology.
Chapter 2 presents a rationale for ecological model-building in the context of a particular
system of interest to the author, the pine-mor food web. Stages in model formulation are
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