Tropical rain forests : an ecological and biogeographical comparison

350 Pages·2005·71.294 MB·English

by  Richard B Primack, Richard Corlett

An Ecological and
Biogeographical Comparison
Richard Primack and
Richard Corlett
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© 2005 by Blackwell Science Ltd
a Blackwell Publishing company
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First published 2005 by Blackwell Science Ltd
Library of Congress Cataloging-in-Publication Data
Primack, Richard B., 1950–
Tropical rain forests: an ecological and biogeographical comparison /
Richard Primack & Richard Corlett.
p. cm.
Includes bibliographical references and index.
ISBN 0-632-04513-2 (pbk. : alk. paper)
1. Rain forests. 2. Rain forest ecology. I. Corlett, Richard. II. Title.
QH86.P75 2005
577.34—dc22 2004009785
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Contents
Preface, viii
Acknowledgments, x
Many Tropical Rain Forests, 1
What are tropical rain forests?, 3
Where are the tropical rain forests?, 4
Rain forest environments, 8
Rain forest histories, 17
Origins of the similarities and differences in rain forests, 24
Many rain forests, 27
Conclusions, 29
Further reading, 29
Plants: Building Blocks of the Rain Forest, 30
Plant distributions, 32
Rain forest structure, 33
How many plant species?, 34
Widespread plant families, 37
Neotropical rain forests, 51
Asian rain forests, 57
Rain forests in New Guinea and Australia, 65
African rain forests, 66
Madagascan rain forests, 70
Conclusions and future research directions, 71
Further reading, 74
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vi contents
Primate Communities: a Key to Understanding Biogeography
and Ecology, 75
What are primates?, 75
Old World versus New World primates, 76
Primate diversity, 81
Primate diets, 82
Primate communities, 85
Primates as seed dispersal agents, 94
Conclusions and future research directions, 95
Further reading, 97
Carnivores and Plant-eaters, 98
Carnivores, 98
Herbivores of the forest floor, 111
Conclusions and future research directions, 129
Further reading, 131
Birds: Linkages in the Rain Forest Community, 133
Biogeography, 134
Little, brown, insect-eating birds, 139
Forest frugivores, 143
Fruit size and body size, 154
Flower visitors, 155
Ground-dwellers, 160
Woodpeckers, 165
Birds of prey, 167
Scavengers, 169
Night birds, 170
Migration, 172
Comparison of bird communities across continents, 173
Conclusions and future research directions, 176
Further reading, 177
Fruit Bats and Gliding Animals in the Tree Canopy, 178
Fruit- and nectar-feeding bats, 178
Feeding habits, 181
Flying behavior, 183
Foraging behavior, 184
Bats as pollinators and seed dispersal agents, 187
Fruit bat conservation, 188
Gliding vertebrates, 189
Conclusions and future research directions, 195
Further reading, 197
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contents vii
Insects: Diverse, Abundant, and Ecologically
Important, 198
Butterflies, 199
Ants, 206
Termites, 218
Social wasps, 222
Bees, 223
Conclusions and future research directions, 230
Further reading, 232
The Future of Rain Forests, 233
Different forests, different threats, 233
The major threats, 241
The forces behind the threats, 254
Global climate change, 260
How bad is it?, 263
Rain forest extinctions, 266
Solutions, 267
Conclusions and future research directions, 278
Further reading, 281
References, 282
Index, 307
Color plate section between pp. 150 and 151
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Preface
In the popular imagination, the tropical rain forest consists of giant trees tower-
ing above a tangle of vines and beautiful orchids below, with colorful birds, tree
frogs, and monkeys everywhere abundant. Scientists and visitors quickly realize
that this image is not accurate: animal life, while highly diverse, is not necessar-
ily strikingly abundant, and flowers are often very small and hard to find. But
beyond the difference between perception and reality, there are tremendous
differences among regions. Biologists working in one area rapidly recognize the
special features of the biological community in their area, yet they would find
themselves in highly unfamiliar terrain should they move, for example, from
their accustomed study site in Borneo to a seemingly similar location in New
Guinea. Indeed, even in locations within the same overall zone, such as the
Amazon and Central American forests, there can be differences both dramatic
and subtle from place to place. There are unique plants and animals in every
community, and even those organisms common to other regions are part of a
distinctive mixture of species that interact in ways readily distinguishable from
other forests. Thus, the tendency of both popular media and science to make
sweeping statements about “the rain forest” is highly misleading.
On a larger scale, rain forests on different continents have fundamentally
different characteristics that make each of them unique. In many earlier books
on rain forests, authors such as Paul Richards in The Tropical Rainforest and Tim
Whitmore in An Introduction to Tropical Rain Forests tried to describe the unifying
properties of rain forests on each continent—features such as the high diversity
of trees species and the low nutrient status of the soils. They took comparable
examples from each region and emphasized certain principles of tropical ecology
that are true on all continents. However, this emphasis on commonalities meant
that readers could—and often did—easily overlook the fact that each of these
rain forests has its own unique features of plants, animals, climate, topography,
and past history. Our goal in writing this book is therefore to redress this over-
sight by emphasizing the ways in which the major rain forest areas are special.
We believe this approach can suggest new research questions that can be
investigated in comparative studies of rain forests in different regions. At the
end of each chapter, we suggest specific new approaches, sometimes involving
experimental methods, that could be used to develop new research questions.
Finally, in the last chapter we consider the unique threats faced by rain forests in
each area of the world and suggest strategies for conservation. Such topics may
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preface ix
have relevance to policy initiatives aimed at protecting rain forest habitats
—initiatives that currently are based upon a misunderstanding that the various
communities would respond in the same manner to the same methods of
management.
We hope that readers will come away with an appreciation that our planet is
host to not one monolithic tract of rain forest, but many unique tropical rain
forest habitats, all worthy of study and protection.
Richard Primack and Richard Corlett
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Acknowledgments
Anyone attempting to write a book that makes simple clear statements about the
whole range of tropical ecology, biogeography, and conservation, quickly reaches
the limits of their own knowledge. Books can be studied and articles examined.
But in the end, it is the tropical ecologists themselves who must be consulted for
the accuracy of impressions and ideas, and to explain facts which seem confus-
ing. Therefore, we have many people to thank for their expertise in making this
book as accurate as possible, for providing colorful examples, and also for saying
when we really do not have the data to make definitive statements.
The book is greatly improved by the numerous images supplied to us from
photographers throughout the world. These people are identified by name next
to their photographs. We would especially like to thank Tim Laman in making
his collection of outstanding slides available to us. The photographs were organ-
ized by Dan Primack.
An extended overview of this topic was read and commented on by Tim
Laman, Ted Fleming, Robin Chazdon, Rob Colwell, Linus Chen, Mike Sorenson,
Cam Webb, and Mark Leighton. Individual chapters were read by J.R. Flenley,
Geoff Hope, Chris Schneider (Introduction), Ian Turner, John Kress, Ghillean
Prance, Chris Dick (Chapter 2), John Fleagle, Cheryl Knott, Colin Chapman
(Chapter 3), Tom Kunz, John Hart (Chapter 4), Mercedes Foster, David Pearson,
Fred Wasserman (Chapter 5), Tom Kunz (Chapter 6), James Traniello, Phil
DeVries, David Roubik (Chapter 7), and Kamal Bawa and Peter Feinsinger (Chap-
ter 8). Tigga Kingston assisted in writing an early draft of parts of Chapters 4
and 6.
Vivi Tran and Elizabeth Platt were the principal research assistants for the
project, and read and commented on all the chapters. Kerry Falvey provided
advice on organization. Two reviewers engaged by Blackwell to read the manu-
script gave us many useful suggestions. We greatly appreciate all their efforts.
A Bullard Fellowship from Harvard University and a Visiting Lectureship from
the University of Hong Kong to one of us (Primack) provided time for research
and writing.
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many tropical rain forests 1
Many Tropical Rain Forests
It is easy to make generalizations about tropical rain forests. Travel posters,
magazine articles, and television programs give the casual observer the impres-
sion that tropical rain forests from any spot in the world are one interchangeable
mass of tall, wet trees—the canopy filled with brightly colored birds, chirping
tree frogs, and acrobatic monkeys, the ground level home to silent predators,
tangled vines, and exotic flowers. This popular perception has been useful be-
cause it creates a compellingly attractive image of an untamed, beautiful place
that is, on the one hand, a source of infinite mystery and adventure—and on
the other, a fragile natural treasury that must be protected. Both conservation
and ecotourism rely on this generalized image to promote the idea of tropical
rain forests as a “good thing” to be preserved and enjoyed. Yet, beneficial as this
image may be in encouraging travel and conservation, it obscures the fact that
the world’s tropical rain forests have major differences from one another in
addition to their obvious similarities.
A major drawback of this generalized image is that it encourages a belief that
saving “the rain forest” is a single problem with a single, universally applicable,set
of answers. Nothing could be further from the truth. There are many differentrain
forests, all of which need action for protection, but this action must be targeted
at the specific threats present in each region and adapted to the specific ecolog-
ical characteristics of each rain forest. Policies, tactics, and techniques that work
in one region may prove ineffective or even disastrous in another. The major
differences between the tropical rain forests in different regions also mean that
successes in one region will not compensate for losses in another. The task we
are faced with is not “saving the rain forest”, but “saving the many rain forests”.
Scientists also have usually emphasized the common appearance of rain for-
ests on different continents and highlighted examples of similar-looking species
in separate regions of the world (Whitmore 1984, 1998; Richards 1996a). This
emphasis on the common features of rain forests worldwide has had the unin-
tended effect of discouraging research that makes comparisons between regions.
The assumption that all rain forests are alike has also led to a tendency to fillgaps
in the scientific understanding of one rain forest region by reference to studies in
other regions. This tendency in turn gives the false impression that our under-
standing of rain forests is greater than it really is, so that scientific research that
could fill the gaps is given a low priority. It also implies that differences between
regions are minor, at least in comparison with the similarities.
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2 chapter 1
Fig. 1.1 The currect global distribution of lowland tropical rain forests. (Courtesy of
UNEP World Conservation Monitoring Centre, 2004.)
Our principal reason for writing this book is that we do not believe that the
differences between rain forests are minor. It is our contention that the various
rain forest regions are sufficiently distinct from one another that they merit
individual consideration. In this book, therefore, we will compare the major rain
forest regions of the world. The three largest of these rain forest regions are in
the Amazon basin of South America, in the Congo River basin of Central Africa,
and on the everwet peninsula and islands of Southeast Asia (Fig. 1.1). There are
also two smaller and very distinctive rain forest regions on the giant islands of
Madagascar and New Guinea. We will show that the rain forests of these five
regions are unique biogeographical and ecological entities, each with many dis-
tinctive plants, animals, and ecological interactions that are not found in the
other regions.
Rain forests occur outside of these core areas as well, but they are less extens-
ive in area and usually less diverse in species. There are rain forests in Central
America and coastal Brazil that are basically similar in species composition to
those found in the Amazon, but have fewer species and occupy a much smaller
area. Similarly, the rain forests of Sri Lanka and the Western Ghats of India
resemble those of Southeast Asia, and Australian rain forests have many sim-
ilarities to the more extensive and diverse forests of New Guinea. Each of these
many areas has numerous noteworthy features and unique species, which we
will mention in this book, but the focus will be on the differences among the
five main regions. In addition, there are also small but distinctive areas of rain
forest on many tropical oceanic islands.
Each rain forest region has different geographical, geological, and climatic
features; each region supports plants and animals with separate evolutionary
histories; and each region has experienced different past and present human
impacts (Table 1.1) (Mittermeier et al. 1999). These differences have important
implications for understanding how rain forests work and deciding how they
should be exploited or conserved. Results from scientific research in one region
may not apply in the others. At the end of each chapter, we suggest comparative
investigations and experiments that could provide deeper insights into rain for-
est biology. Similarly, conservation measures or methods of sustainable exploita-
tion that are successful in one area may not work as well in another. Each rain
forest area, and even local areas within each of these regions, must be viewed
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