Ecology: A Textbook

289 Pages·1980·9.68 MB·English

by  Professor Dr. Hermann Remmert (auth.)

Hermann Remmert
ECOLOGY
A Textbook
With 189 Figures
Springer-Verlag
Berlin Heidelberg New York 1980
Professor Dr. HERMANN REMMERT
Fachbereich Biologie
der UniversiHit
Lahnberge, Karl-von-Frisch-Stral3e
3550 Marburg/Lahn, FRG
Translated by:
MARGUERITE A. BIEDERMAN-THORSON Ph. D.
The Old Marlborough Arms
Combe, Oxford, Great Britain
2nd German Edition: Oko[ogie
© by Springer-Verlag Berlin Heidelberg 1980
ISBN-13: 978-3-540-10059-1 e-ISBN-13: 978-3-642-67635-2
001: 10.1007/978-3-642-67635-2
Library of Congress Cataloging in Publication Data. Remmert, Hermann. Ecology, a
textbook. Translation ofOkologie. Bibliography: p. Includes index.!. Ecology. I. Title.
QH 54I.R4313.574.5 80-13091.
This work is subject to copyright. All rights are reserved, whether the whole or part of
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illustrations, broadcasting, reproduction by photocopying machine or similar means,
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Under §54 of German Copyright Law where copies are made for other than private use,
a fee is payable to the publisher, the amount of the fee to be determined by agreement
with the publisher.
© by Springer-Verlag Berlin· Heidelberg 1980
The use of registered names, trademarks, etc. in this publication does not imply, even in
the absence of a specific statement, that such names are exempt from the relevant
protective laws and regulations and therefore free for general use.
Cover design: W. Eisenschink, Heidelberg.
2131/3130--543210
Preface
The wealth of the natural sciences
no longer consists in the abundance of facts,
but in the way they are linked together.
ALEXANDER VON HUMBOLDT
There is no dearth of books on ecology. Why write yet
another?
Each person is different, and each views the problems in a
different way. Each emphasizes different aspects and
describes them in a different style. When I was a student I
often found certain books more helpful than others, and
I still think it is useful to have a variety of presentations
from which to choose. This variety also allows the student
to appreciate the diversity within the field of ecology.
I have devoted considerable effort to making this book
readable. Throughout I have refrained from using specialized
terminology - thus also avoiding the problem that many
terms are used differently in the various areas of ecology.
Straightforward English is quite sufficient to describe
complicated situations. Furthermore, precisely defined terms
are usually associated with detailed quantitative descriptions,
whereas we are concerned with a general understanding
of the dynamics of ecology. For similar reasons I have
tried to rely as little as possible on mathematical discussions.
All too often, in recent years, people have overlooked the
fact that mathematics - like language - can give only a
description, albeit an especially precise one.
Further, I have made a point of presenting not only well
established results, but also current hypotheses that give
expression to the dynamic development and orientation of
present-day ecology. In so doing I hope to stimulate further
work in the field, to arouse the reader's curiosity;
hypotheses are the salt and pepper of research.
And finally, I have stressed the functional relationships
within the complex that is ecology. Every phenomenon has
its causes and its effects - a dualism that frequently goes
unnoticed.
The first German edition was soon sold out. In preparing the
second, I am aiming at a simultaneous English edition to
m~ke the book available to readers outside Germany.
Marburg/Lahn, July 1980 HERMANN REMMERT
Contents
A. Ecology: the Basic Concept.
B. Autecology . 3
I. Theory of Autecology 5
II. The Range of Ecological Factors. 6
III. Life-Form Types 6
IV. Ecological Factors. 13
1. Salinity and Osmotic Pressure 13
2. Temperature 24
3. Nutrition. 37
4. Light. 52
5. Oxygen Supply 57
6. Fire 60
7. Interspecific Competition 62
8. The Conspecific as an Environmental
Factor 73
9. Ecological Neurobiology 75
10. Other Ecological Factors 80
11. Periodic Changes in the Habitat 80
12. The Interaction of Environmental
Factors. 85
13. Special Problems. 93
V. Case Studies in Autecology 94
1. Surface Chemistry and Choice of Biotope 94
2. Synchronization with Habitat
Conditions 96
3. The Biology of Game Animals:
Capercaillie and Roe Deer. 100
C. Population Ecology 107
I. Theory of Population Ecology 109
II. Population Genetics . 110
III. Demography 115
IV. The Distribution of Organisms in Space 121
V. Maintenance of an Average Population
Density 126
1. Autoregulation 126
2. Predator-Prey Systems 133
3. Food Supply and Population Density. 155
4. Abiotic Factors and Population Density 158
VIII Contents
VI. Case Studies in Population Ecology.. 161
1. Euphydryas: the Splitting of a Species
into Separate Populations. . . . 161
2. Field Crickets: the Mechanisms
Underlying Population Dynamics. 164
3. Bat and Moth: the Coevolution of a
Predator-Prey System. . . . 168
4. Larus: the Fusion of Species 173
D. Ecosystems . . . . . . . 177
I. Theory of Ecosystems 179
II. "Natural" Ecosystems 181
III. The Climax Concept: Microcosmic and
Seral Successions . . 182
IV. Statics of Ecosystems. . . . . . . .. 185
V. Ecosystem Dynamics. . . . . . . .. 192
1. The Cycling of Matter in Ecosystems. 192
a) The Circulation of Water . 193
b) Cycling of Other Materials 194
2. The Energy in Ecosystems 198
a) Productivity . . . . . . 198
b) Measurement ofa Stand . . 206
c) Food Chains and Food Webs . 209
d) Energy Flux . . . . . . . . 211
VI. The Significance of Animals in an Ecosystem 226
VII. Changeable and Constant Ecosystems . 231
VIII. Constancy and Stability . . 240
IX. Case Studies of Ecosystems . 250
1. Lake Nakuru (Kenya) . 250
2. Spitsbergen. . . 253
3. Central Europe . 261
E. Outlook. . 267
References . . 273
General Books on Subjects Related to Ecology . 284
Subject Index . . . . . . . . . . . . . .. . 285
A. Ecology: the Basic Concept
The term "ecology" was introduced more of long development, and the only systems
than a hundred years ago by Ernst in which man can live at all are those exist
Haeckel; "biocenosis" was introduced in ing at present.
1877 by Mobius, and "ecosystem" in the For example, consider the air we breathe.
1920's by Woltereck. Now, after 100 years We know that the oxygen in the earth's
of ecological research, these words are be atmosphere, on which all animal life de
ing discovered anew. They have become pends, is derived from photosynthesis by
modern, and echo on all sides. But ecology plants, which is usually written
is not a doctrine of salvation. As Ernst 6 CO + 12H 0
2 2
Haeckel put it, ecology is the Haushalts
(+light)~C6H1206 +602 +6H20.
lehre der Natur - the study of the econom
ics of nature. It is a strict natural science, If this formula were a complete description
but must overcome considerably greater of the situation, the production of oxygen
difficulties than physiology, genetics or would continue until all the carbon dioxide
biochemistry; it must accommodate a vast or water had been used up. Of course, this
array of different parameters, so that has not occurred - the reaction can also
predictions become infinitely laborious. proceed in the opposite direction:
With the organism most thoroughly stud
ied physiologically - the human - it is still C6 H1206+ 602 +6H20~6C02+ 12H20.
impossible to predict responses reliably. This formula describes the overall process
Ecologists face the problem of judging in of respiration in microorganisms, plants,
advance the reactions and developments of and animals. Because the conversion of
complex systems within which an ex CO -0 by photosynthesis has, on the av
2 2
tremely large number of genetically dis erage, exceeded the reconversion of 02-
tinct microorganisms, plants, and animals CO the amount of oxygen on earth built
2,
live. Even to attempt such a task is a daunt up in the course of evolution. If the rates of
ing prospect. But the attempt must be conversion and reconversion had been
made. identical, so that the organisms used up all
We are also confronted with a special mod the oxygen the plants produced, neither we
ern dilemma of ecology. Today this old, nor the other animals now inhabiting the
strict natural science has suddenly become earth would be alive.
a focus of public interest. It is called upon Green plants, in fact, can be regarded as
for assistance in making political de the first great polluters of the environment.
cisions, and in so doing it is forced to move While their photosynthesis was creating
out of the realm of pure science. This ne the present-day oxygen atmosphere of the
cessity represents a notable danger to ecol earth, and the earth's surface was being
ogy. Many have come to regard it as a oxidized, many organisms that had existed
method of generating results which, if assi before the plants - adapted as they were to
duously applied, will help mankind to life without oxygen - were doomed to per
achieve steadily increasing well-being and ish.
happiness. Nothing could be further from An amount of organically bound or oxi
the truth. Ecological systems are the result dizable carbon equal to the amount of oxy-
2 Ecology: the Basic Concept
gen produced by photosynthesis must be for particular conditions; population ecol
present on the earth. Some of it is in a form ogy, in which the primary question is why
familiar to everyone, the fossil fuels (an populations of microorganisms, plants,
thracite and bituminous coal, petroleum, and animals do not reproduce without
natural gas, graphite). But these represent limit, but rather maintain certain approxi
only a minute fraction of the earth's re mately constant numbers; and research on
serves. The remainder is present in all sedi ecosystems, which is concerned with the
ments, in a finely subdivided form - so cycling of matter and the flow of energy,
finely that even in future it will not be with the way ecosystems function, and
made available for use as a source of en with questions of the stability and elastic
ergy. (This is a reassuring thought: even ity of ecosystems.
burning of all the fossil reserves will cause In all three areas various approaches - mi
no appreciable change in the oxygen con crobiological ecology, botanical ecology,
tent of the atmosphere. However, by such and zoological ecology of the ocean, fresh
burning we raise the carbon dioxide con water, and land - ought to be combined to
tent of the atmosphere; the consequences provide general insight. But because of the
to the earth's climate are incalculable.) extent of the field, and for historical rea
sons, this collaborative ideal has not been
We live on this earth, then, because of the
realized. As a result, the terminology has
way natural ecosystems have evolved over
become utterly confused. Even the word
millennia, and we can hardly expect the in
"ecology" is used with quite different
sights of ecological scientists to generate a
meanings by botanists and zoologists. (In
utopian world. But ecological theory may
botany it refers only to experimental,
be crucial to our continued existence. We
chiefly physiologically oriented research,
can live on earth under the conditions now
whereas in zoology pure field research is
prevailing, and under no others. As a pure
taken for granted as part of the science.
science, ecology is concerned with under
Botanical field studies, together with his
standing the balance and turnover of mat
torical biogeography, are considered to lie
ter and energy in nature. In its applied
in the area of geobotany.) Moreover, the
form, ecology faces the problem of dis
terms used in the terrestrial domain are
covering how the conditions essential for
quite different from those in limnology
present-day life can be maintained.
and oceanography. In this book, therefore,
The field of ecology is generally subdivided we shall avoid technical terms almost en
into three areas: autecology, the study of tirely (for a review of ecological terminol
the requirements of particular organisms ogy see Tischler, 1975).
B. Autecology
B. Autecology
I. Theory of Autecology made in the gene pool, sexual isolation
from the original population is necessary.
Two organisms that require the same re This separation, the process by which new
source compete for this resource if they oc species are formed, is called speciation.
cupy the same area. The competition be Speciation - sexual isolation from neigh
tween the two is stronger, the greater the bors - is thus an adaptive process which of
number of requirements they have in com fers selective advantages in that it enables
mon. It becomes overpowering when the specialization and alleviates competition.
ecological demands of the two organisms The genotypes selected in the struggle for
are identical in all details. Two different existence, then, are those best suited to the
species with identical ecological require original situation as well as those able to
ments can live together only if the number colonize other habitats because of specific
of individuals is so small that they never adaptations and those which, by virtue of
actually enter into competition - that is, if other adaptations, are least exposed to
they do not utilize their habitat to full ca competition from the original species in
pacity. (The circumstances under which the original habitat.
this situation can arise are discussed in The fact is often overlooked that acquisi
connection with the regulation of popula tion of new adaptive features is never an
tion density, in the section on population unalloyed benefit - in all cases, adaptation
ecology.) In general, however, it is possible takes its toll. Side effects can include
for two species to coexist in the same space slower development, a lower rate of repro
while competing for the same resources if duction, reduced mobility, impaired resis
they differ in various aspects of their biol tance to changes in the environment, or a
ogy or their ecological requirements. combination of these and other symptoms.
Competition is most vigorous, then, be Another possible side effect, a high rate of
tween members of a single species. This ex energy consumption, is found only in ex
tremely strong intraspecific (as opposed to ceptional cases, and then is usually tempo
"interspecific" - between different species) rary. Because high energy consumption
competition is the driving force for evolu must always be coupled with increased
tion, as Darwin described it more than a food intake, and there is hardly ever a sur
century ago. The best-adapted genotypes plus of food available, organisms must
in each situation are continually selected, adopt other strategies for adaptation. In
and those less suited are eliminated from terms of the sort of cost-benefit analysis
the contest. Organisms can escape this made by economists, the price of an
competition in two different ways. As a re adaptation would be set against its value to
sult of selection they either become the organism - the advantage of escaping
adapted to the conditions in a different intraspecific competition.
habitat, or they evolve a different way of So far no such cost-benefit analyses have
life, with different ecological requirements been carried out to completion. In mutants
in the same habitat. The new features ac of flowering plants that thrive on heavy
quired as adaptations must become geneti metal soils, dry-matter production is gen
cally fixed. If permanent changes are to be erally reduced by 20-50% (Ernst, 1975).