Table Of ContentFragile Ecosystems
Fragile Ecosystems
Evaluation of Research and Applications
in the Neotropics
Edited by
Edward G. Farnworth and Frank B. Golley
A Report of The Institute of Ecology (TIE)
June, 1973
Springer Science+Business Media, LLC
Edward G. Farnworth and Frank B. Golley
Institute of Ecology
Rock House
University of Georgia
Athens, Georgia
Library of Congress Cataloging in Publication Data
The Institute of Ecology.
Fragile ecosystems.
1. Ecology-Tropics. 2. Ecology-Latin America.
1. Farnworth, Edward G., ed. II. GoUey, Frank B.,
ed. III. Title.
QH541.155 1974 574.5'098 74-8290
AU rights reserved
No part of this book may be translated or reproduced in
any form without written permission from Springer-Verlag.
©1974 by Springer Science+Business Media New York
Origina1ly published by Springer-Verlag New York Inc. in 1974
ISBN 978-3-540-06695-8 ISBN 978-3-642-86763-7 (eBook)
DOI 10.1007/978-3-642-86763-7
FOREWORD
The Institute of Ecology (TIE) was organized to provide a mech
anism for addressing ecological and environmental issues that were
beyond the special interests of ecology as a profession. One method of
evaluating such issues is the workshop, and this report describes the
results of the third TIE workshop on a major environmental subject.
The ecology of tropical regions is of interest to all the inhabitants of
the biosphere. The tropics provide mankind with both the opportunity
for and the challenge of essential resources, land for settlement and
development, and waters for numerous uses. Moreover, they provide
examples of misuse of the landscape, fragility of ecological systems,
and serious environmental problems. Unfortunately, the study of the
ecology of the tropics has not kept pace with the ecology of other
regions. The purpose of this report, therefore, is to determine the
research approaches that will lead to advances in our theoretical un
derstanding of tropical systems and, more importantly, in the applica
tion of that knowledge to human problems. Although the principal
focus of the report is on the neotropics, it will be useful to the full
spectrum of persons concerned with the tropics around the world
government officials, sCientists, students of ecology, and others.
TIE is especially pleased to thank the numerous scientists and ad
ministrators who participated in the workshop and who contributed to
this report.
Arthur D. Hasler, Director, TIE
v
PREFACE
Ordinarily, research proceeds on a very broad front with in
dividual investigators pursuing the questions they consider most sig
nificant and interesting. Seldom do researchers have an opportunity
to review jointly the state of their subject and suggest research ob
jectives from a collective vantage point. The National Science Foun
dation (NSF) of the United States of America has provided ecologists
with an unusual opportunity to review the state of neotropical ecology
and to recommend research priorities.
These deliberations were designed to provide guidance to the NSF
on their allocation of research support. However, NSF also wanted
to make the results of the study available to agenCies and scientists
throughout the America~. Therefore, this research review deals with
ecology in the A!p.erican tropics .in as broad a perspective as possible
in order to be useful to a variety of scientists and decision makers in
many countries and of varied political persuasions. This report is
published in Spanish and English and is available at a reasonable cost
to all interested persons in the Americas and elsewhere.
The TIE study is based on correspondence with more than 2,500
persons interested in tropical ecology worldwide. More than 400
persons contributed papers, advice, and ideas, and more than 100
persons actively met to discuss and write about the research needs
for tropical ecology. The writers and editors of the report are
acknowledged in each section. Those many other unidentified con
tributors we thank collectively-their support has been exceedingly
helpful throughout the study. We also thank our hosts at the Depar
tamento de Biologla, Universidad de Antioquia and the Jardin Bota
nico for their assistance at the planning meeting in Medellin, Colom
bia, and the staff of the Instituto Interamericano de Ciencias Agrico-
las (IICA-CTEI) for their help at the Workshop in Turrialba, Costa Rica.
Finally we thank the workshop staff, Douglas Pool, in particular,
and the headquarters staff at the University of Georgia Institute of
Ecology, especially Silvia Halfon, Margaret Shedd, Deborah Duncan,
Jimmie Sue Wagner, and Nancy Bunker, for their service to the project.'
We also thank Peggy Farnworth for proofreading the manuscript.
Frank Golley
Edward Farnworth
(Athens, 1974)
vii
SUMMARY
The objective of the Tropical Ecology Research report is to review
the state of knowledge in tropical ecology and to recommend profitable
areas for research. The report is divided into six sections that deal
with populations, communities, ecological succession, impact of tech
nology on environment (excluding urban and manufacturing questions),
regional impacts of man, and mechanisms to support research. The
emphasis is on fundamental theory or patterns characteristic of neo
tropical populations, communities, and landscapes and on how man
interacts with these units. Gaps in knowledge and research questions
are identified. It is intended that the report be useful to the National
Science Foundation (the agency supporting this project), and govern
ments and scientists throughout tropical America and other tropical
areas.
It was concluded that the challenge of tropical ecology is to discover
ways of disturbing the natural tropical ecosystem for the benefit of
man, while not jeopardizing the richest source of biological information
on the earth. Population studies that consider population dynamics,
genetics, environmental physiology, and natural selection are basic
to understanding these dynamiCS of natural and man-dominated tropical
systems. Specific recommendations are directed toward a sustained
yield of products useful to man without degradation of productivity,
richness, or long-term stability:
1. Comparative studies of the morphology, physiology, behavior,
and population structure of temperate and tropical species and of
paleotropical and neotropical species.
2. Comparative studies of time and energy budgets of tropical in
dividuals and populations, assessing the position of a species in a
community by examining the rates and strategies of energy acquisi
tion and expenditure.
3. Evaluation of the impact of exotic species in order to develop
better preventative and management techniques for these species.
4. Floristic and systematic studies emphasizing life history and
ecological data on important ecological research sites are needed to
provide background information for ecologists.
ix
x Summary
5. In planning the establishment of national parks and preserves,
consideration should be given to the predictions of island biogeography
theory and to results obtained in preserves already established, since
extinction rates tend to increase as areas decreases.
6. The creation of greater awareness of the threat of pests to the
agricultural- and forest-development programs and human populations.
7. Determination of the high-priority pest and disease problems
on a regional basis and then to develop around them truly integrated
pest-management research efforts utilizing personnel and financial
resources from the collaborating countries and international sources.
A systems approach will be essential to integrate methodologies and
different disciplinary inputs into a workable, rational system of pest
management at the agroecosystem level.
8. Characterization of the factors responsible for the natural
population regulation of principal insect pe sts.
9. Epidemiological studies conducted for the more important
disease agents. Also, life-system studies of competitors, hyper
parasites (if any), antagonists, conditions influencing inoculum pro
duction and dispersal, host defense mechanisms, and environmental
conditions critical to the disease process are needed.
10. The "center of diversity" of major crop plants should be
worked intensively in search of usable genes for pest resistance.
This approach should serve as the prinCipal element in the integrated
control of crop pests and possibly those of animals.
11. New breeding schemes must be devised to combine the high
yielding, uniform-product advantages of the "monoculture" system
with animal and crop-breeding schemes that will endow greater
genetic diversity and consequently greater agroecosystem stability.
12. Methods should be' investigated for management of weed
popUlations that would minimize the use of herbicides. Very little
is known about the long-term effects of a heavy herbicide burden in
the tropical ecosystem and on traditional agriculture.
Ecological research on ecosystem structure and function must be
conceived, executed, and interpreted in the context of the needs and
realities of society in the tropics at the same time that it must also
be responsive to the further development of ecological theory. The
concept of the ecological system is a useful unifying concept for the
design of research questions relevant to both ecological theory and
society's needs, because the needs of society are related to the forces
acting upon it as part of a system. The research questions that
emerge from this approach are as follows:
1. The hypothesis that process rates (e.g., productivity, decom
position, mineral cycling, succession, etc.) appear higher in the
tropics than in analogous temperate regions needs to be tested in a
Summary xi
in a variety of tropical environments.
2. Rates of productivity, decomposition, and cycling must be
known to assess, for example, potential organic yields, capacities
for waste processing, and water storage alternatives. Rates of suc
cession are requisite for developing management practices relating
to ecosystem recovery silting of water bodies and devising new kinds
of yield systems.
3. Both short- and long-term cyclic phenomena must be incor
porated into ecosystem study.
4. External and internal factors that control ecosystem structure
and function must be investigated in order to understand management
of ecosystems. Natural systems provide free work and with proper
management reduce maintenance costs.
5. Studies of data on the dynamics of the important nutrient
element cycles that occur during clearing and forest destruction,
during cropping, and during abandonment and forest recovery are
needed.
6. Determination of the optimal rates at which ecosystems oper
ate is of primary importance to ecological theory. We also must
know how much stress an ecosystem can tolerate without losing its
capacity to recover.
7. Procedures for tropical research that will facilitate the devel
opment and use of the necessary interpretive framework are recom
mended. These procedural steps include research design in the con
text of the next highest level of biological organization, development
of integrating mechanisms to summarize, interpret, and present the
data, include energy network diagrams and models, and consistent
reporting and the use of comparable techniques.
8. More data are needed to test the hypothesis that diversity and
stability (or better, resistance to perturbation) are directly related.
9. Increased study of regional coupling of ecosystems is neces
sary since coupling involves the synthesis of theory at a level of or
ganization that is of practical importance to the needs of society.
Remote sensing, delineation, and sampling of watershed units, and
techniques of modeling to plan research and manipUlate data are
needed.
10. Research sites should be selected not by the present distribu
tion of stations but by the data necessary to test general principles
of ecosystem structure and function, which also are applicable to the
needs of man in the tropics.
Secondary succession has been studied mainly in temperate areas
and knowledge of the tropical process is derived from studies in only
a few localities. Many ecological studies including secondary vegeta
tion restrict themselves to lists of the species found in secondary
xii Summary
communities. Whereas these data are useful, few generalizations
can be derived from them. Recommendations for research include
the following:
1. Establishment of permanent centers (which may be existing
stations) to study succession over the long time periods.
2. Establishment of replicated plots for studying short- and long
term effects of disturbance.
3. Regional studies of secondary communities should be under
taken with preferences given to areas where past history is accurately
known.
4. "Ecological life histories" (autecological population studies)
of organisms prominent in and/or having a conspicuous effect on dis
turbed habitats are needed. A given ecological life history should
extend across as wide a range of habitats as possible and should in
corporate some reassessment of the taxonomy of the organism.
5. Experiments in adding and subtracting specific organisms or
groups of organisms (e.g., all ants, all insects, all vines) from many
of the types of communities are needed.
6. Taxonomic treatments focused on prominent groups in badly
disturbed habitats should be encouraged. These should proceed hand
in-hand with the development of easily accessible data-retrieval
systems for all the information available (not only taxonomic) concern
ing particular organisms.
7. Knowledge of soil changes occurring in the course of secondary
succession is needed.
8. Detailed publication of data from the studies mentioned above,
in journals or other publications of wide circulation (not only data
banks) is needed. It is imperative that these receive widespread
translation into Spanish, English, and Portuguese.
Human use of the land can be grouped into such categories as agri
culture, grazing, forestry, industry, urban development, and transpor
tation. Each of these activities uses the environment in a special way,
requiring certain inputs and resulting in specific outputs. Thus, the
problem of analysis of the impact of man not only concerns the main
tenance of a given system, but also the inputs and outputs of the
system, which link it to all other man-dominated or natural ecosystems.
Recommendations for research are as follows:
1. The environmental controls of plant and animal agricultural
production in the tropics should be studied.
2. studies of traditional crops and wild plants and animals as new
food sources are essential.
3. Traditional agricultural systems, multiple cropplng systems,
integrated agricultural operations using plants and animals should all
Summary xiii
be investigated utilizing modern techniques of system analysis where
costs and benefits from an environmental, economic, and social point
of view are considered.
4. The value of faunal and floral resources as sources of food,
sport, recreation, and genetic material should be assessed.
5. Development of a sound ecological base for tropical forest
management is needed.
6. The impact of reservoirs on river basins, aquatic flora and
fauna, man living in river basins, disease organisms, and soil erosion
should be inve.stigated.
7. Standard methods of obtaining and reporting Climatological
data are needed in tropical areas since these data are fundamental to
understanding and predicting processes in all ecological systems.
8. Finally, research is needed on the impact of transportation
networks, mining, tourism, and other land use patterns in the tropical
environment and the interaction of these activities with other activi
ties and processes. Urban and industrial problems merit special
attention.
Land, water, and atmosphere are intimately li!J.ked through com
plex biological and geophysical processes without respect to national
political boundaries or even to continental limits. "Action at a
distance" is indeed an accurate metaphor to describe the interregional
and international impacts of one major ecosystem upon another. Better
understanding of regional ecosystem interactions can be of substantial
help in planning to maximize the contribution of natural resources to
human welfare. Recommendations for research are the following:
1. Expanded studies of the biogeochemistry of major tropical
drainage basins are required to establish the initial physical, chem
ical, and biotic characteristics of their streams and associated es
tuaries.
2. The relative roles of various energy sources such as man
groves, algae, and river-borne detritus in tropical estuaries should
be established,with particular emphasis on the effect of perturbation
of these sources on food webs and fish yields. Detailed effects of al
terations in fluvial regimes on the productivity of rivers, lakes,
marshes, deltas, and estuaries should be determined.
3. Field studies should be undertaken to determine the quantita
tive importance of marshes, other wetlands and running water eco
systems for production and support of pelagic fishes and of waterfowl
and other birds that migrate between continents and as habitat for
resident birds and mammals.
4. Additional research should be directed toward more fully es
tablishing the acute and chronic limits of aquatic and estuarine or
ganisms toward pollutants, temperature, and wide fluctuations in
