Table Of ContentStratification of tropical forests as seen in leaf structure: Part 2
Tasks for vegetation science 21
HELMUT LIETH HAROLD A. MOONEY
University of Osnabriick, F.R. G. Stanford University, Stanford Calif, U.S.A.
Stratification of tropical forests
as seen in leaf structure
Part 2
by
B. ROLLET
eH. HOGERMANN
and
1. ROTH
Kluwer Academic Publishers
Dordrecht I Boston I London
Library of Congress Cataloging in Publication Data
Rollet, B. (Bernard)
Stratification of tropical forests as seen in leaf structure, part
2 I by B. Rollett, Ch. Hagermann, and I. Roth.
p. cm. -- (Tasks for vegetation science; 21)
Includes bibliographical references.
ISBN-13: 978-94-010-7335-6
1. Leaves--Anatomy. 2. Leaves--Tropics--Anatomy. 3. Rain forest
plants--Anatomy. 4. Rain forest plants--Ecology. I. Hagermann,
Ch. II. Roth, Ingrid. III. Title. IV. Series.
QK649.R64 1989
581.4·97--dc20 89-15548
ISBN-13: 978-94-010-7335-6 e-ISBN-13: 978-94-009-1872-6
001: 10.1007/978-94-009-1872-6
Published by Kluwcr Academic Publishers,
P.O. Box 17,3300 AA Dordrecht, The Netherlands.
Kluwer Academic Publishers incorporates the publishing programmes
ofD. Reidel, Martinus Nijhoff, Dr W. Junk and MTP Press.
Sold and distributed in the U.S.A. and Canada
by Kluwer Academic Publishers,
101 Philip Drive, Norwell, MA 02061, U.S.A.
In all other countries, sold and distributed
by Kluwer Academic Publishers Group,
P.O. Box 322, 3300 AH Dordrecht, The Netherlands.
All Rights Reserved
© 1990 by Kluwer Academic Publishers
Softcover reprint of the hardcover 1s t edition 1990
No part of the material protected by this copyright notice may be reproduced or
utilized in any form or by any means, electronic or mechanical,
including photocopying, recording or by any information storage and
retrieval system, without written permission from the copyright owner.
CONTENTS
FOREWORD by the series editor and the volume editor vii
INTRODUCTION by Ingrid Roth xi
LEAF MORPHOLOGY by B. Rollet 1
LEAF VENATION by Christi anne Hogermann 77
PECULIAR SURFACE STRUCTURES OF TROPICAL LEAVES
FOR GAS EXCHANGE, GUTTATION, AND LIGHT CAPTURE by
I. Roth 185
FINAL REMARKS by Ingrid Roth 239
INDEX 241
FOREWORD BY THE SEFlliS EDITOR AND THE VOLUME EDITOR
Since the start of the Task for Vegetation Science The three volumes by Roth (1984, 1987) and
series (T:VS), 21 volumes have appeared. The Rollet et at. (this volume) were included in our
series has found its proper place in the scientific series because they provided unique information
community. Its initial goal was first to provide an from the tropical rain forest, a vegetation type
outlet for monographic treatments of in novative from which the least information of this kind is
approaches in vegetation sciences; secondly, the available. The data compiled in these volumes will
documentation of special data sets important for be used in modelling transfer rates of various
future practical or theoretical treatments and, kinds in the future. It is unlikely that anywhere in
thirdly, the translation into English of important the tropics will it again be possible to collect such
treatments of vegetation science related books a wealth of data. The volumes have been lauded
published in other languages. for that fact but, on the other hand, they have been
The series has volumes published in all three criticized for various reasons. We have therefore
categories. The content of the volumes is often asked Professor Roth to answer the criticism by
interdisciplinary in nature and emphasins topics reviewers where necessary, especially those com
where vegetation science is used to benefit other ments where the discussion could improve or
fields. Several of these volumes were especially clarify objectives. In the following paragraphs, she
successful on the market. answers the reviewers on those points which we
One of the basic requirements for each author/ agreed upon:
editor of a volume is to provide a clean manuscript
in English. In the past, this was a serious obstacle "Proctor and Garwood cntIcize that the author
for many projects which would otherwise have divided the woody plants into three height cate
been accepted in our series. In many cases, the gories (above 30 m, 10-29 m, and below 10 m).
mother tongue of the editor was not English, and But, as usual, the people who made the inventory
his style and grammar had to be corrected by also introduced the classification into height cate
many people who were polyglots or not from the gories. I only received the material from Dr.
scientific field. This might have caused some Rollet, who collected it. The abovementioned
unusual expressions or unfamiliar terminology. classification is the one generally used in tropical
However, this is a major problem of our time. If forestry. The cloud forest of Rancho Grande was
the members of the scientific community request classified in a similar way by other forestry
to be monolingual, they must accept the fact that experts. Proctor also criticizes that individuals of
style and grammar of that language vary from less than 10 cm dbh are excluded from the
country to country, that mistakes occur, and that inventory.
sentence structures suffer. As a series editor, one In the introduction of T:VS.l7, I emphasized
can smooth some of the problems but not all, and that most samples were taken from trees with an
it does not seem appropriate to override the average diameter of between 10 em and 1 m or
personal style of a respected colleague one has more at breast height. But then I emphasized on
invited to serve as the key person for an individual page two that the principal objective of the
volume. Furthermore, it seems financially irre dendrological studies was the collection of wood
sponsible to burden volumes with the cost of a samples for technological purposes. The inventory
complete linguistic correction when the scientific was made to study the properties of the wood and
content is understandable. the economic return of the forest when cut. No
B. Rollet et at.: Stratification of Tropical Forests as seen in Leaf Structure, Part 2, pp. vii-x.
© 1990 Kluwer Academic Publishers. Printed in the Netherlands.
viii
ecological interest was involved in these studies. further from the parent tree'. There is a difference
The collection of fruits was only an adventitious between autochory in general and explosive
by-product. But, with reference to the treelets and mechanisms. As is easily checked in any book
shrubs with a dbh of less than 10 cm, the reader dealing with fruit dispersal, true explosive
finds a special note on page two of the book mechanisms are actually rare and extremely
stating: 'However, some trees do not even reach specialized. There are quite a few herbs which
20 cm dhb in the adult stage, such as some show explosive mechanisms (see Roth 1977,
Rubiaceae, Capparidaceae, and Melastomaceae. 'Fruits of Angiosperms', Encyclopedia of Plant
These trees were also included, however, in an Anatomy). But fruits or seeds are usually 'shot
attempt to cover the maximum number of genera forth' a few meters. In the interior of the forest,
and species.' This means that trees and shrubs with this is an adequate dispersal distance. The world
a dbh of less than 10 cm were also included. Not record in 'shooting' is held by Hura crepitans at 45
included were herbs, forbs, tree seedlings, vines m. But this is a species of dry and hot habitats
and epiphytes. The objective of the primary collec where the vegetation is open and where, at times, a
tion was trees, not the whole flora. strong wind is blowing. Most autochorous plants
A further point mentioned by Proctor is gaps are less effective. Autochory is a general concep
and phases. Many authors emphasize that the tion of dispersal types in which no other agents are
natural regeneration of tropical forests occurs in involved. All plants with dehiscing fruits are
gaps. This seems to be the paradigm of the present considered to be autochorous (see also page 14 of
time. Rollet (Bois et foret tropiques no. 201 :3-34: volume 17). However, many of the autochorous
no. 202:19-34, 1983. "La regeneration naturelle mechanisms are not effective. The fruits just open
dans les trouvees. Un processus general de la and drop the seeds. In a herb, the seeds remain
dynamique des forets tropicales humides") thinks close to the mother plant. The same is true for a
that there is a grossly unbalanced exaggeration of high tree, when no air movement takes place.
the importance of gaps. However, the environmental conditions in the
Concerning phases in tree life: the literature of upper crown regions are different from those in
the last two decades (in English) seems to present the forest interior. At times, we have to take into
these phases as a new finding and makes proposals account the strong winds, in which case fruits or
for an updated terminology. Foresters were aware seeds may be taken far away. Furthermore, fruits
of juvenile and senescent individuals in their or seeds falling down from high crowns may
forests long before 1970. But here again, the become deviated. For these reasons, even a not
inventory was made for other purposes, and not very effective autochorous method may become
to study regeneration. For more details, we refer effective in high trees, especially when dispersal
to Rollet, B. (1969) "Etudes quantitatives d'une takes place during the dry season.
foret dense humide sempervirente de plaine de Finally, concerning the complaint of Proctor
la Guyane Venezuelienne." Trav. Lab. Forest. and Garwood that the tables on page 39 are in the
Toulouse, T.l, Vol. 8,Art.l:I-36. wrong place, I completely agree. I asked the
In his critical review of Volume 17, Proctor also publishers to put them in the right place, but they
claims a statement which he thinks is a contradic refused for financial reasons. The computer print
tion to another assertion. On page 15, I say that ing has its disadvantages - there is little possibility
'The fact that the height of release has little for any corrections to be made after the appear
influence on dispersal distance provides one of the ance of the first proofs, except when the author
reasons why explosive dispersal mechanisms are pays for them.
not confined to trees or other plants which attain a Answering the questions and criticisms of
great height' and (on page 139) that 'Autochory Nancy Garwood: fruiting times were observed by
seems to be advantageous when the seeds fall from Dr. Rollet and a team of experts over several
a great height, in this way they may be removed years. On page 1 and in the bibliography, the
IX
publications of Rollet concerning this topic are dispersal mechanisms. In this case it is possible
cited. However, I do not understand of what really to follow the increase or diminution of
'critical' importance the preservation of fruits certain dispersal types in the vertical direction.
should be for descriptive purposes. Fruits and For those who are working in tropical forests, it
seeds usually have strong cell walls and the is already commonplace that stratification exists in
photographs show that the tissue types are per the forest. There is a microclimatic gradient,
fectly preserved. The author has 48 years' experi particularly concerning humidity and illumination.
ence, in the preservation and processing of plant While, in the undergrowth, illumination is a limit
material for anatomical studies. Another misund ing factor, a high degree of humidity prevails; in
erstanding of my publication is the assumption the crown region, by contrast, illumination is often
that it would be useful for field identification. Who very strong and drought may be considerable
could carry the microscope to the forest, make when strong winds are blowing. Leaves of herbs,
slides and preparations there to identify fruits? low treelets and shrubs are thus adapted to
particularly when the person in question is humidity and are often 'artists' in capturing low
perhaps unable to distinguish different tissue types, light intensities, while leaves in the crown region
even when the legend underneath explains them? are more xeric, leathery and have a well developed
Furthermore, I never consider a morpholog palisade parenchyma. It is also well known that
ical-anatomical work on fruits and seeds of animal life is more vigorous in the lower forest
Venezuelan Guiana a 'substitute' for a study on layers and additionally it shows a certain 'stratifi
fruits on the Dutch Guianan flora. Of what use cation' concerning the different species preferring
should this comparison be? Garwood misses a certain stratum (ground animals, etc.). Plants
convincing explanations why some species of have adapted to these gradients in the forest, even
Sapotaceae have a higher number of individuals in their dispersal types. Anemochory, for example,
and others have not. Many factors are involved is only advantageous in high trees. That autochory
here, of which many are not known. Garwood also seems to be more successful in high trees than
admits that most wind-dispersed species are tall. in low herbs is likewise a result of the air move
Was this not to be expected? Furthermore, the ment and possibly also of the deviation of seeds or
classification of height categories has some dis fruits by obstacles. There is no 'stratification
advantages: when we regard a tree of 30 m height hypothesis', but gradation in the forest concerning
as tall, a tree of 29 m height is not short. The leaf morphology and anatomy as well as dispersal
overall statistics are thus of limited value. Results due to a microclimatic gradient, is just a fact (as I
have to be considered with more care - certain can demonstrate in my next publication 'Leaf
trends in certain families or genera are of impor structure of a Venezuelan cloud forest as related
tance. The fact that the number of seeds is reduced to microclimate'.)
towards the upper strata is of phylogenetic value. In the review of the book on leaf structure,
What the statistics show is that anemochory drasti Professor Ernst commented on my use of 'ridicu
cally diminishes towards the lower strata, as had lous decimal points', as he phrased it. He forgets
been expected, and that zoochory prevails in the that plant anatomists read four digit numbers from
forest has never been denied. It is, however, the microdrive of their microscopes and these are
surprising that autochorous and auto-zoochorous calibrated in m,u. These numbers converted into
methods increase in number towards the canopy. the CGS System yield the figures presented in the
Instead of confronting the height categories with book. These numbers are familiar to plant anato
the number of species (and individuals) and their mists and they are very valid, indeed, usually down
dispersal mechanisms (Table 1 of Garwood), to at least the third figure on the dial.
which is misleading, it would be much more "The main value of this study for ecosystems
informative to confront height categories and analyses lies in the completeness of the material,
percentages of species (and individuals) with their which allows comparisons in many ways. Up to the
x
present time, an area of such a large extension has possible cost. The success of the series on the
never been studied morphologically and anatom market, including the volumes by Professor Roth,
ically (barks, leaves, fruits and seeds). The advant seems to justify our decisions. We hope, therefore,
age was the inventory in which not only the that the current volume will be as successful as the
number of species, but also the number of individ previous ones. Since this volume completes the
uals was known. Usually, conclusions are drawn documentation of the entire project, it may even
after general information is available. The results stimulate more users to buy the complementary
obtained from a thorough study of all species and T:VS Volumes 6 and 17. We also hope that our
individuals showed contradictions with the usual readers understand from this foreword that we as
dogma. It is unlikely that ecologists will be able to editors, and publisher as well, respect the com
conduct studies of this type in the future." ments of the reviewers of our books. Whatever we
can adopt from their suggestions will be done. We
So much for the responses for the volume editor.
hope to keep the series going in the future on the
The publisher and the series editors admit that
same principles and with the same care as at
they too were included in the criticism of the
present, and thank all readers and users of our
reviewers to some extent and that some of the
volumes for their help.
critique directed at Professor Roth should have
been directed at the series editor or the publisher. H. Lieth, Series editor
Weare ready to apologize for any mistakes we
I. Roth, Volume editor
made. Our main objective with the T:VS series is
service to the scientific community at the lowest W. R. Peters, Kluwer Academic Publisher
INTRODUCTION
This volume is the last contribution of a series of With the present book, a further gap concern
studies concerned with the plant material of one ing leaf morphology and leaf venation, as well
and the same area of Venezuelan Guiana. The as some structural peculiarities of physiological
studies originated through a collaboration with the importance, is closed so that an exhaustive survey
forest engineer Dr. B. Rollet, the FAO expert in of bark and leaf morphology and anatomy as well
forest inventory who collected the material of tree as of fruit and seed structure of the plants of a
barks, leaves, fruits and seeds in Venezuelan certain well-known area is herewith given. Not
Guiana around the "Rio Grande", "EI Paraiso", only were hundreds of species studied, but
and "EI Dorado" camps. In the first place, tree structural characteristics were related to "forest
barks of about 280 species of dicotyledons stratification", i.e. to the different micro climatic
belonging to 48 families were studied (family by conditions in the forest, as the height of the trees
family) by Roth in separate publications which and shrubs studied was known. It is of common
mainly appeared in Acta Botanica Venezuelica knowledge that in the lower forest layers, light is a
and in Acta Biol6gica Venezuelica (see the bibli limiting factor, while humidity is sufficiently avail
ography in Roth 1981). A comprehensive survey able, whereas in the crown region, insolation is
of bark structures, principally from the area of strong, but drought may play an important part. In
Venezuelan Guiana, was given in "Structural the undergrowth and lower layers, we thus find the
patterns of tropical barks" by Roth (1981). hygromorphic shade leaf, while in the uppermost
Secondly, leaf structure of 42 species belonging to layers and in emergent trees, the sun leaf with
28 families of dicotyledons, chiefly trees but also some xeromorphic features prevails. Furthermore,
herbs and lianas, of the same region, was studied zoo chary predominates in the lower strata, where
with the aim of estimating leaf consistency and as autochory and wind dispersal are more com
texture ("Anatomia y textura foliar de plantas de la mon to the upper storey and in emergent trees. In
Guayana Venezolana", Roth 1977). Some mate order to distinguish the different storeys, the trees
rial of the leaf collection of Dr. Rollet from the and shrubs were separated into three categories:
same region was left to the disposal of Dr. M.
A - very tall trees of 30 m height or more,
Pyykko for morphological and anatomical studies
a - trees between 10 m and 29 m in height,
(Pyykko 1979). An exhaustive survey of the leaf
and
anatomy of 232 species belonging to 48 different
aa - small trees and shrubs of less than 10m in
families from the collection of Dr. Rollet in
height.
Venezuelan Guiana, was given by Roth (1984)
("Stratification of tropical forests as seen in leaf This subdivision into height categories was made
structure"). Lastly, morphology, anatomy, and by the inventory experts. Additionally, mature
dispersal of fruits and seeds of 58 families with leaves of juvenile plants of different heights (e.g. 1
375 species from the same collection in Venezuelan m, 5 m, 7 m, 12 m etc.) were available so that a
Guiana was investigated by Roth (1987) ("Stratifi comparison between mature leaves of one and the
cation of a tropical forest as seen in dispersal same species at different stages of tree develop
types"). Wood structure was studied separately by ment and at different forest strata could be made.
the forestry department of the Universidad We owe this knowledge to the initiation of an
Central de Venezuela in Merida. inventory carried out by the Ministry of Agricul-
B. Rollet et al.: Stratification afTropical Forests as seen in LeafS tructure, Part 2, pp. xi-xv.
© 1990 Kluwer Academic Publishers. Printed in/he Netherlands.
