Table Of ContentSpringer Series in Wood Science
Editor: T. E. Timell
M. H. Zimmermann
Xylem Structure and the Ascent of Sap (1983)
J.F. Siau
Transport Processes in Wood (1984)
R.R. Archer
Growth Stresses and Strains in 'frees (1986)
W.E. Hillis
Heartwood and Tree Exudates (1987)
S. Carlquist
Comparative Wood Anatomy (1988)
L. W. Roberts/P.B. Gahan/R. Aloni
Vascular Differentiation and Plant Growth Regulators (1988)
C. Skaar
Wood-Water Relations (1988)
J.M. Harris
Spiral Grain and Wave Phenomena in Wood Formation (1989)
B. J. Zobel / J. P. van Buijtenen
Wood Variation (1989)
P. Hakkila
Utilization of Residual Forest Biomass (1989)
J.W. Rowe
Natural Products of Woody Plants, (1989)
P. Hakkila
Utilization of
Residual Forest Biomass
With 240 Figures
Springer-Verlag Berlin Heidelberg New York
London Paris Tokyo Hong Kong
DL PENTTlfUuaaLA
Finnish Forest Research Institute, Unioninkatu 40A, SF-00170 Helsinki, Finland
Series Editor:
TORE E. TIMELL
State University of New York, College of Environmental, Science and Forestry,
Syracuse, NY 13210, USA
Cover: Transverse section of Pinus lambertiana wood. Courtesy of Dr. Carl de Zeeuw,
SUNY College of Environmental Science and Forestry, Syracuse, New York
ISBN-13: 978-3-642-74074-9 e-ISBN-13: 978-3-642-74072-5
DO I: 10.1007/978-3-642-74072-5
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© Springer-Verlag Berlin Heidelberg 1989
Softcover reprint of the hardcover 1st edition 1989
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To Pirkko
Preface
An increase in the demand for wood results in improved recovery and less residual
biomass in the forests. Paradoxically, interest in forest residue as a renewable source
of raw material seems to be in a reverse ratio to its availability in a certain area.
Finland and Sweden are probably more dependent on forestry and forest in
dustries than any other developed countries in the world. A sufficiency of raw ma
terial for integrated forest industries is vital for the national economy of both
countries, and a great deal of attention is being paid to the long-term potential
of unutilized biomass left behind in logging operations. Furthermore, since these
countries possess no reserves of fossil fuels, and since their per-capita consump
tion of primary energy is exceptionally high, they also consider unmerchantable
forest biomass a realistic source of indigenous energy.
A joint Nordic research project on harvesting and utilization of logging
residue was carried out in 1969-1976 under the auspices of the Nordic Research
Council on Forest Operations. This fruitful cooperation soon gave rise to related
national projects in Sweden, Finland, Norway, and Denmark, stimulating further
research and producing practical applications. Concurrently, particularly after the
worldwide energy crisis in 1973, research on all aspects of utilization of forest bio
mass mushroomed in the United States, Canada, and the Soviet Union. An ex
plosive increase occurred in both the number and diversity of biomass studies. Ac
cording to Young (1977), world literature on forest biomass quadrupled in 6 years
in the mid-1970s. This ever-accelerating trend seems to continue.
The Editor of the then new Springer Series in Wood Science, Professor T. E.
Timell of the State University of New York, surprised me in May, 1982, with a
letter offering an opportunity to produce a monograph on the utilization of forest
biomass. I took his letter as a great honor, and recognized the need for a holistic
presentation of the problem area. However, I personally knew many distinguished
scientists with much more suitable background and experience to write the book
in English.
Gradually, after a thorough examination of this opportunity I understood it
as recognition of the joint Nordic efforts for the improved utilization of all parts
of trees. Since only a small fraction of the Nordic literature is reported in the ma
jor world languages, these results are not well known internationally. When I
realized that the work could now be reviewed in an international forum and in
tegrated in a monograph of world literature, with some hesitance I decided to ac
cept the offer.
This book grew out of forest technology research at the Finnish Forest
Research Institute (FFRI) and a 3-year project on Complete Utilization of Forest
Biomass, financed by the National Research Council for Agriculture and Forestry
of the Academy of Finland. The research program was financially supported by
SITRA, the Finnish National Fund for R!!search and Development. The exchange
VIII Preface
of ideas and information with distinguished foreign scientists has been an essen
tial part of past work. Among the many colleagues who over a period of 20 years
contributed to the research programs referred to above, I wish to express my par
ticular thanks to Harold E. Young, John R. Erickson, Peter Koch, and Rodger
A. Arola of the United States of America; Imants levin of the Soviet Union; P.o.
Nilsson of Sweden; Olav Gislerud of Norway; Wolfgang Knigge of the Federal
Republic of Germany; and Veijo Heiskanen, Bror-Anton Granvik, Matti Kark
kainen, Ilpo Palenius, and N.E. Virkola of Finland.
The object of this monograph is to provide an interdisciplinary but still simple
reference to various aspects of utilization of the presently unmerchantable parts
of trees. The proportion of residue left behind in logging operations is largest in
the virgin forests in the north and in the tropics where very few scientific data are
available. Furthermore, since long transport distances and other serious con
straints will probably prevent the recovery of forest residue from remote areas un
til some future time, this book is primarily a review of forest residue potential in
countries where forestry has a long tradition, and where the forests are under
regular silvicultural management. Because most of the scientific data and prac
tical experience is from northern Europe, Pinus sylvestris (Scots pine) and Picea
abies (Norway spruce) are the species most frequently mentioned in the text. Had
the book been written by another author from another geographic region, the em
phasis would most probably have been different.
The goal is a balanced review of scientific literature and recent practical devel
opment in the field of forest biomass utilization. The scope covers aspects of
forest management, mensuration, ecology, logging and transport, wood technolo
gy, processing, and utilization.
Although the use of residual biomass is, to a great extent, an economic prob
lem, with some minor exceptions this review does not include an economic evalua
tion of alternative methods of biomass utilization. Due to differences in the cost
of labor and capital, logging technical and socioeconomic conditions, and vary
ing exchange rates between countries, the inclusion of economic comparisons was
not considered feasible. Because the intention is a brief, but comprehensive
presentation, a cautious generalization of complex phenomena has been required.
The production of this book would not have been possible without financial
support from the Foundation for Research of Natural Resources in Finland and
the Finnish Cultural Foundation. Their generous contribution provided me with
the much needed opportunity to concentrate exclusively on writing during the
final phase of the work. I was fortunate to enjoy the steadfast support of the Fin
nish Forest Research Institute and its Director, Professor Aarne Nyyssonen. The
Institute kindly permitted me the use of its published and unpublished scientific
material in writing the book.
Many staff members of the Department of Forest Technology, Finnish Forest
Research Institute, contributed to the book. Hannu Kalaja was extremely effective
and helpful in the collection of field material over many years. Hannu Aaltio was
responsible for the data processing of the several unpublished Finnish biomass
studies used in Chapter 2. Maija Tuuri, with the assistance of Heidi Koskinen, pa
tiently, carefully and with dedication typed the manuscript, not only once, but
several times, as the text underwent new.revisions. Leena Muronranta made most
Preface IX
of the line drawings, always with care and skill. Pentti Sairanen briefed several Rus
sian publications on biomass utilization. Timo Heikka, Risto Helkio, Pirkko
Kinanen, Tapio Nevalainen, Raija Siekkinen, Aune Suinuniemi, and Jaakko
Sumanen assisted in many ways. Special appreciation is expressed to Kaija Kan
ninen who always knew how to make things happen. Without her encouragement,
thoughtfulness, and unselfish sacrifices, far beyond the call of duty, I would not
have been able to complete the work.
Several colleagues reviewed parts of the manuscript. Their constructive criticism
and advice were most useful in pointing out inaccuracies, enabling me to remove
many imperfections. For their part in reviewing one or more chapters, my warm
thanks are due to Aaro Alestalo, OlIi Eeronheimo, Rihko Haarlaa, Osmo Liiri,
Bruno LOnnberg, Eino Malkonen, Seppo Kellomaki, Raili Voipio, and especially
to Harold E. Young and Matti Kiirkkainen. I am also indebted to Anne Johnson,
Marita Nasman-Repo, and Valerie Vainonen, who checked and improved the
English language.
Illustrations were contributed from many sources, which are mentioned in the
figure legends. I am particularly indebted to T. E. Timell and W. A. Cote of the
SUNY College of Environmental Science and Forestry, Syracuse, NY USA, for the
illustrations of the structure of wood in stem, branches, and roots. Photographic
material was submitted also by Rodger A. Arola of the Forestry Sciences Laborato
ry at Houghton Mich., Allan Bruks of Bruks Mekaniska AB, Ken Harrison of
Koehring Canada, Imants levin and V. Lazdan of Scientific and Industrial
Research Association SILAVA, Hannu Kalaja and Erkki Oksanen of the Finnish
Forest Research Institute, Peter Koch of Wood Science Laboratory Inc., Timo Kyt
tala of Lokomo Forest Oy, V. Lauren of Mackmyra Cellulosaflis AB, Goran LOn
ner, Jonas Palm, and Kerstin Tordmar of the Swedish University of Agricultural
Sciences, Arthur Riedacker of Agence Fran9aise Pour la Maitrise de l'Energie,
Pekka Saranpaa of the University of Helsinki, and many others. John R. Erickson
and Andy Baker, U.S. Forest Products Laboratory, kindly supplied me with many
important reference publications. I am also grateful to the authors and publishers
who kindly gave me permission to reproduce previously published figures and
tables.
It gives me great pleasure to express my gratitude to the publisher, Springer
Verlag, and the Editor, T. E. Timell, for the opportunity to produce this book in
the Springer Series in Wood Science. Their patience, flexibility, advice, assistance,
and encouragement from the beginning to the very end of the project made the ex
perience inspiring and pleasant.
Finally, I wish to express my deep gratitude to my mother and my family for
their unceasing understanding and support. My wife, Pirkko, had to sacrifice a
great deal during the years I prepared the book. Not only did she give her support
and encouragement for the work in all possible ways, but she also gave me linguistic
advice and even made the attractive operational drawings which illustrate biomass
harvesting systems much more clearly than would have been possible to express in
words. Without her dedicated support the book would not be a reality.
Puuksanharju Peninsula, Finland
May 1989 P. HAKKILA
Contents
1 Introduction................................................... 1
2 Residual Forest Biomass as a Raw Material Reserve ............ . . . . 11
2.1 Biomass Components of a Tree... . . . . . . . . .. . .. . . . . . . . . . . 14
2.1.1 Tree Crown............................................ 17
2.1.1.1 Development of the Crown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.1.1.2 Foliage Mass .......................................... 21
2.1.1.2.1 Moisture Content of Foliage. . . . . . . . . . . . . . . .. . . . . . . . . . . . . 22
2.1.1.2.2 Vertical Distribution of Foliage Mass . . . . . . . . . . . . . . . . . . . . . 23
2.1.1.2.3 Seasonal and Annual Variation in Foliage Mass. . . .. . .. . . . . 26
2.1.1.2.4 Effect of Tree Size on Foliage Mass ...................... 27
2.1.1.2.5 Effect of Crown Class on Foliage Mass . . . . . . . . . . . . . . . . . . . 32
2.1.1.2.6 Effect of Tree Species on Foliage Mass ................... 34
2.1.1.2.7 Effect of Atmospheric Pollution on Foliage Mass. .. .. . . . . . 36
2.1.1.3 Composition of Branch Mass. .. . . .. . . . . . . . . . . . . .. .. . . . . . 38
2.1.1.3.1 Moisture Content in Branches. . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.1.1.3.2 Percentage of Bark in Branches. . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.1.1.3.3 Dead Branches as a Biomass Component. . . . . . . . .. .. . . . . . 41
2.1.1.4 Crown Mass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.1.1.4.1 Crown Ratio .......................................... 44
2.1.1.4.2 Vertical Distribution of Crown Mass. . . . . . . . . . . . . . . . . . . . . . 46
2.1.1.4.3 Effect of Tree Size on Crown Mass.. . . . . . . . . . . . . .. . .. . . . . 49
2.1.1.4.4 Effect of Stand Density and Crown Class on Crown Mass. . 54
2.1.1.4.5 Effect of Tree Species on Crown Mass. . . . . . . . . . . . . . . . . . . . 55
2.1.2 Unmerchantable Top ................................... 58
2.1.2.1 Percentage of Bark in the Unmerchantable Top. . . .. .. . . . . . 60
2.1.2.2 Mass of Unmerchantable Top. . . . . . . . . . . . . . . . . . . .. . .. . . . . 62
2.1.3 Stump and Roots. . .. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . 64
2.1.3.1 Distribution of Stump-Root System Components. .. . . . . . . . . 67
2.1.3.2 Percentage of Bark in Stump and Root Mass. . . . .. . . . . . . . . 68
2.1.3.3 Dry Mass of the Stump-Root System. . . . . . . . . . . .. . . . . . . . . 69
2.2 Composition of Whole-Tree Biomass. . . . . . . . . . . . . . . . . . . . . . 72
2.3 Biomass of an Entire Stand ............................. 79
2.4 Forest Biomass Inventory ............................... 84
2.5 Quantity of Residue in Practical Logging Operations ....... 88
2.5.1 Estimating the Quantity of Logging Residue. . . . . . .. . . . . . . . 90
2.5.2 Examples of the Quantity of Logging Residue . . . . . . . . . . . . . 93
XII Contents
3 Technical Properties of Residual Tree Components 100
3.1 Anatomical Structure of Residual Tree Components ....... . 101
3.1.1 Compression Wood in Softwood Branches ................ . 107
3.1.2 Tension Wood in Hardwood Branches ................... . 114
3.1.3 Juvenile Wood in Stem Tops ............................ . 119
3.1.4 Anatomical Characteristics of Root Wood ................ . 122
3.2 Cell Dimensions in Residual Tree Components ............ . 127
3.2.1 Cell Dimensions in Branch Wood ....................... . 129
3.2.2 Cell Dimensions in Stem Tops .......................... . 135
3.2.3 Cell Dimensions in Stump and Root Woods .............. . 140
3.3 Chemical Composition of Residual Tree Components ...... . 145
3.3.1 Primary Constituents in Residual Tree Components ....... . 149
3.3.2 Extractives in Residual Tree Components ................. . 159
3.3.2.1 Extractives in Wood and Bark .......................... . 162
3.3.2.2 Extractives in Foliage .................................. . 167
3.3.3 Inorganic Materials in Residual Tree Components ......... . 172
3.4 Basic Density of Wood and Bark in Residual Tree
Components .......................................... . 177
3.4.1 Basic Density of Wood and Bark in Branches ............ . 180
3.4.2 Basic Density of Wood and Bark in Stem Tops ........... . 186
3.4.3 Basic Density of Wood and Bark in Stumps and Roots .... . 190
3.5 Heating Value of Residual Tree Components .............. . 194
4 Recovery of Residual Forest Biomass ............................. 204
4.1 Harvesting Whole Trees. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
4.1.1 The Basis of Whole-Tree Harvesting . . . . . . . . . . . . . . . . . . . . . . 205
4.1.2 Felling for Whole-Tree Harvesting . . . . . . . . . . . . . . . . . . . . . . . . 207
4.1.2.1 Motor-Manual Felling .................................. 208
4.1.2.2 Mechanized Felling and Bunching. .. . . . . . . . . . . . .. . . . . . . . . 212
4.1.3 Off-Road Haulage of Whole-Tree Material ................ 218
4.1.3.1 Off-Road Haulage with Skidders. . .. . . . . . . . . . . . .. . . . . . . . . 218
4.1.3.2 Off-Road Haulage with Forwarders.. . . . . . . . . . . . . .. . . . . . . . 221
4.2 Relogging Slash from Cutovers. . . . . . . . . . . . . . . . . . . . . . . . . . . 225
4.2.1 Collection of Slash. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
4.2.2 Off-Road Haulage of Slash. . . . . . . . . . . . . . . . . . . . . .. . . . . . .. 228
4.3 Continuously Progressing Swath Harvesters ............... 230
4.3.1 The Basis of Swath Harvesting .......................... 231
4.3.2 Operation of the Swath Harvesters . . . . . . . . . . . . . . . . . . . . . . . 233
4.3.3 Swath Harvester Prototypes ............................. 236
4.4 Harvesting Stump and Root Mass. . . . . . . . . . . . . . . . . . . . . . . . 240
4.4.1 Logging Characteristics of Stump-Root Systems. . . .. . . . . . . . 240
4.4.1.1 Dimensions of Stump-Root Systems. . . . . . . . . .. . . .. . . . . . . . 241
4.4.1.2 Power Requirement of Stump Extraction . . . . . . . . . . . . . . . . .. 244
4.4.2 Extraction of Complete Trees. . . . . . . . . . . . . . . . . . . .. . .. . . .. 247
