The Central Amazon Floodplain: Ecology of a Pulsing System

530 Pages·1997·16.32 MB·English

by  Wolfgang J. Junk (auth.)

Ecological Studies, Vol. 126
Analysis and Synthesis
Edited by
M.M. Caldwell, Logan, USA
G. Heldmaier, Marburg, Germany
O.L. Lange, Wtirzburg, Germany
H.A. Mooney, Stanford, USA
E.-D. Schulze, Bayreuth, Germany
U. Sommer, Kiel, Germany
Ecological Studies
Volumes published since 1992 are listed at the end of this book.
Springer-Verlag Berlin Heidelberg GmbH
W.J. Junk (Ed.)
The Central Amazon
Floodplain
Ecology of a Pulsing System
With 137 Figures and 72 Tables
'Springer
Dr. Wolfgang J. Junk
Max-Planck-Institut fur Limnologie
Postfach 165
24302 Plon, Germany
ISSN 0070-8356
ISBN 978-3-642-08214-6
CIP data applied for
Die Deutsche Bibliothek-CIP-Einheitsaufnahme
The central Amazon floodplain: with 72 tables/Wolfgang J.
Junk (ed.).
(Ecological studies; Vol. I26)
ISBN 978-3-642-08214-6 ISBN 978-3-662-03416-3 (eBook)
DOI 10.1007/978-3-662-03416-3
NE: Junk, Wolfgang}. [Hrsg.]; GT
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Foreword
For a long time wetlands have received little attention from eco
logical researchers worldwide. In part, the reason may be that
neither the terrestrial nor the aquatic ecologists, the limnologists,
felt themselves competent to study areas which combine within
themselves terrestrial as well as aquatic conditions of life, and
instead they preferred to concentrate, or to limit, their efforts
on ever more detailed investigations of their traditional subjects. In
part, too, this neglect may be due to the fact that the word "wet
land" is a collective name which comprises many, very distinct
landscape units, from swamps and peatbogs to river floodplains.
Even certain arctic regions with permafrost soil must be taken as
"wetland" since the summer sun melts the frozen surface of the
ground, creating temporary pools of high bioproductivity in the
form of the well-known mosquito nuisance.
The ecosystems of wetlands thus show in themselves terrestrial
and aquatic characteristics, either spatially intermingled or tem
porally alternating. Floodplains, for example, are seasonally inun
dated for periods of up to many months and are during those
periods aquatic biotopes, whereas in the more arid months they
lay dry and represent terrestrial habitats. In the equatorial
lowlands where the temperature remains practically constant over
the course of the whole year, that alternation is caused by the
changing water levels of the rivers and their discharges, and
thus indirectly by the pluvial climates of the catchment basins.
The arctic summer pools, however, follow the thermic climate of
their environment. As we see, "wetland" is not an unequivocal
concept.
It is only in recent decades that ecological research has started to
turn its activities to the wetlands. The reason was a new, purely
scientific interest, and equally the prospect of utilizing them for the
benefits of the alarmingly increasing human population of the
Earth - and/or the awareness of the threatening destruction of
VI Foreword
those peculiar ecosystems and their generally high biodiversity and
bioproductivity.
Some voluminous publications on wetlands in general that have
come out in recent years - important and valuable as they are -
have the inevitable disadvantage that they have to present, in the
same volume or series of books, all too many different objects of
research comprised under the term "wetland" with their many
different problems and aspects. The various scientific endeavours
are not all directed to one common supreme goal or point of
reference but are individually selected by the scientific or regional
specialties of the authors. The whole vast field of the many different
types of"wetlands" with their, again, different sets of problems and
aspects, if they had already been explored, would yet fill immense
rows of books!
It is now of great merit for Dr. Wolfgang J. Junk, Head of the
Working Group of Tropical Ecology of the Max-Planck-Institute of
Limnology at Plan, Germany, to edit a book that for the first time
presents a complete survey of the existing knowledge on the ecol
ogy of one type of tropical wetland, a huge floodplain, that of the
biggest river on Earth, the Amazon. Just the size of that ecosystem
would justify the dedication of a voluminous monograph to one
particular section of the biosphere. That is equally justified by its
geographical position in the equatorial girdle since it reduces ther
mic seasons and their effects on life to a minimum and all the more
stresses the dominating role of the seasonal "flood pulse" for the
annual life rhythm of the organisms. Finally, the Amazonian
floodplains are to a great extent still scarcely or not at all altered by
modern man's activities, nowadays almost an exception even in the
tropics.
Nobody other than Dr. Junk could be called upon to conceive
the idea of this book. It is no question that he has the greatest,
longest and most diversified experience in that unique ecosystem.
As my doctoral student he worked for over 2 years on the "floating
meadows" of Amazonian rivers, lagoons, and flooded terrains,
studying their flora and fauna in an ecological context. These
floating meadows are closely connected on one hand with the water
- many species of their plants and animals depend on certain pH
values and chemical compositions - and, on the other hand, with
the terrestrial substratum of their biotopes, i.e., the floodplains,
since the life cycles of their plants and animals are exposed to
the seasonal alternations of aquatic and terrestrial conditions.
Subsequently, the peculiar and, until then, scientifically scarcely
Foreword VII
investigated biotopes and ecosystems of the Amazonian
floodplains became the main object of Dr. Junk's research. He
studied them and several of the problems they set under various
aspects and questionings, but with the final goal of understanding
the connections between the parts of the system which make the
whole function.
To meet the wide-ranging demands placed by the production of
a book on such a complex matter with its many different compo
nents, Dr. Junk was able to call on a group of highly competent
colleagues. The staff of his Working Group of Tropical Ecology and
Brazilian scientists who worked together on problems related to
the Amazonian floodplains.
It is a wide goal that Dr. Junk as editor and all the authors of the
chapters have set themselves, and they have achieved it. The book
is a decisive step forward in the endeavour to enhance the compre
hension of such a huge and peculiar ecosystem as that of the Ama
zonian floodplains. The research of such a vast complex is like
composing a great mosaic picture. Many stones, large and small
ones, have to be set in the right places. The collocation of those
stones which are to act as basic points of reference gives a concept
of the whole picture. That is what has been achieved by this book;
the filling in of the remaining lacunas with more details will be a
task for the future. The tropical ecologists are grateful for this great
achievement.
Plon, Germany, Winter 1996 Harald Sioli
Acknowledgments
This book is the result of a long and fruitful cooperation between
the Max-Planck-Institute for Limnology, Plan, Germany, and the
Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus,
Amazonas, Brazil. The cooperation started in 1962 with an agree
ment between the directors of both institutes, Prof. Dr. Harald Sioli
and Prof. Dr. Djalma Batista. In the following years, both institutes
stimulated scientific cooperation on Amazonian ecosystems and
gave as much technical assistance as possible to German and
Brazilian scientists to achieve the work. Since 1980, the studies
have concentrated on a holistic approach to floodplain ecology. We
acknowledge with deep gratitude the help of both institutes, the
Max-Planck-Society and the Brazilian Research Council (CNPq),
which provided financial assistance for the cooperation over sev
eral decades. During the last 5 years, the team received additional
assistance from the SHIFT Program "Studies on Human Impact on
Forests and Floodplains in the Tropics" financed by the German
Ministry for Science and Technology (BMBF), the Brazilian Re
search Council (CNPq), and the Brasilian Environmental Agency
(IBAMA).
Fieldwork in Amazonia was only possible because of the invalu
able experience and friendly help of local technicians, field
workers, and fishermen. I cannot name all of them, but I am espe
cially indebted to Mr. Celso Rabelo Costa and Mr. Uwe Thein, who
have assisted us in Amazonia for many years.
For the typing of the manuscripts, I gratefully acknowledge the
help of my secretaries, Mrs. Gerda Lemke and Mrs. Sabine Meier.
Many of the figures were prepared by my technician, Mrs. Elke
Busdorf. English corrections were made by Mrs. Nancy Weider.
Prof. Dr. Rosemary Lowe-McConnell made final corrections of the
English in all chapters and gave valuable comments. Prof. Dr. Otto
Lange helped to prepare the book for the publishers.
Contents
Part 1: Introductory Remarks
1 General Aspects of Floodplain Ecology
with Special Reference to Amazonian Floodplains
Wolfgang J. Junk . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Definition and General Characterization . . . . . . . . . 6
1.3 The Flood Pulse Concept . . . . . . . . . . . . . . . . . . . . . 8
1.4 Floodplains and Limnological Terminology. . . . . . . 10
1.5 Distribution and Size of Neotropical Floodplains . . 12
1.6 Human Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1. 7 Objectives and Structure of This Book . . . . . . . . . . . 17
Part II: The Physical and Chemical Environment
2 The Large Central Amazonian River Floodplains
Near Manaus: Geological, Climatological,
Hydrological, and Geomorphological Aspects
Georg Irion, Wolfgang J. Junk,
and Jose A.S.N. de Mello . . . . . . . . . . . . . . . 23
2.1 Formation of Va rzea and Igap6 . . . . . . . . . . . . . . . . 23
2.2 Characterization of the Study Area . . . . . . . . . . . . . 29
2.3 Climate and Hydrology . . . . . . . . . . . . . . . . . . . . . . . 30
2.4 Grain Size and Mineralogical Composition . . . . . . . 35
2.5 Sediment Transport and Deposition . . . . . . . . . . . . 37
2.6 Geomorphological Aspects . . . . . . . . . . . . . . . . . . . . 41
2.7 Discussion and Conclusions . . . . . . . . . . . . . . . . . . . 44
XII Contents
3 Chemistry ofVarzea and Igapo Soils and Nutrient
Inventory of Their Floodplain Forests
Karin Furch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.2 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.3 Total Element Content . . . . . . . . . . . . . . . . . . . . . . . 53
3.3.1 Metals (K, Na, Mg, and Ca) . . . . . . . . . . . . . . . . . . . . 53
3.3.2 Nonmetals (C, N, S, and P) . . . . . . . . . . . . . . . . . . . . 54
3.4 Cation Exchange Capacity . . . . . . . . . . . . . . . . . . . . 55
3.5 Content of Soluble Substances
in Aqueous Soil Extracts . . . . . . . . . . . . . . . . . . . . . . . 56
3.6 Bioelement Stock in the Systems and Bioelement
Fluxes Between Soil and Forest Vegetation . . . . . . . 58
3.7 Discussion and Conclusions . . . . . . . . . . . . . . . . . . . 62
4 Physicochemical Conditions in Floodplains
Karin Furch and Wolfgang]. Junk . . . . . . . . . . . . . . 69
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
4.2 Light Regime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.3 Chemistry of Different Water Types . . . . . . . . . . . . 73
4.3.1 The Solimoes/Amazon River Near Manaus . . . . . . . 73
4.3.2 The Negro River Near Manaus . . . . . . . . . . . . . . . . . 77
4.3.3 Terra Firme Affluents . . . . . . . . . . . . . . . . . . . . . . . . 82
4.3.4 Amazonian Rainwater . . . . . . . . . . . . . . . . . . . . . . . . 85
4.3.5 Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
4.4 Physicochemical Attributes
of Different Va rzea Lakes . . . . . . . . . . . . . . . . . . . . . . 94
4.4.1 The Influence of Different Waters on the Chemistry
of Va rzea Lakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
4.4.2 Thermal and Chemical Stratification
and Mixing Patterns . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.4.3 The Oxygen Concentration in Varzea Lakes . . . . . . 100
4.4.4 Processes Within Lakes....................... 104
4.4.5 Land-Water Interactions
and the Bioelement Cycles . . . . . . . . . . . . . . . . . . . . . 1O S
4.5 Discussion and Conclusions . . . . . . . . . . . . . . . . . . . 107