Springer Series in Wood Science – serie

This book is not concerned directly with wood identification, although ability to recognize the wood features discussed in the preceding chapters is essential for work in wood identification. The present chapter is concerned with how wood characters have been and can be used in taxonomic and phylogenetic studies - and also which wood characters are likely or not likely to be useful, in general. In wood identification, a match of an unknown wood with known woods is usually attempted. In systematic application of wood data, similari­ ties and differences among species, genera, and families are assessed ( usually, today, in terms of a cladistic analysis). One should be especially cautious in interpreting relation between taxa the woods of which have attained similar evolutionary levels. This possibility is a very real one, because so many wood features have evolved similarly in phylads that are not closely related to each other. For example, storied wood structure has been attained in a number of phylads independently. By itself storied wood structure cannot be used as an indicator of relationship between two families, but a cladogram ( using a range of phyletically reliable features) might demoo­ strate that two families acquired storied structure before divergence ( a synapo­ morphy) and thereby a strong case for relationship of the two families is made.

The first edition of this book was the first to provide an integrated description of sap ascension from an anatomical and functional point of view. The second edition opens with the three-dimensional aspects of wood anatomy. The cohesion-tension theory and new evidence are introduced in response to recent controversies over the mechanism of sap ascent in plants. The physiology, anatomy and biophysics of xylem dysfunction are discussed and new insights into hydraulic architecture are reviewed with special emphasis on physiological limits on maximum transpiration and how hydraulic architecture limits gas exchange, carbon gain and growth of plants. The text concludes with a description of xylem failure and pathology. The book highlights fascinating areas of current research with the aim to stimulate more work in the future.

As in other scientific fields, the importance of boundary areas in wood research, such as that between lignin chemistry and hemicellulose chemis- try, continues to increase. Although the utilization of individual wood components has advanced to an appreciable extent, research into oligo- merie or polymerie compounds of two or more different components has made little progress. By contrast, in other fields, glycoproteins and pro te- oglycans have been found to form biochemical active centers in enzymes and microbes. The association between lignin and carbohydrates in lignified plants was first recognized in 1866. However, research has advanced slowly because of difficulty in the isolation and determination of wood glycocon- jugates, whieh likely have an important influence on the formation of wood, pulping behavior, pulp quality and digestibility by ruminants. Most plants contain both hydrophilie polysaccharides and hydrophobie lignins in their tissues.Lignins have been recognized to not only give mechanieal strength or rigidity to a tree or wood, but also to prevent invasion by fungi, and provide cell wall material, especially in the tracheids and vessels that deliver water extracted from the soil to the top of woody plants. How- ever, in trees, lignins have been found to interact with the polysaccharides, partieularly hemicelluloses, with whieh they coexist, leading to the forma- tion of another chemical component, a kind of glycoconjugate. Therefore, it is necessary to inc1ude lignin or p-hydroxycinnamie acids in any discus- sion on wood hemieelluloses.

This book on the Nondestructive Characterization and Imaging of Wood by Professor Voichita Bucur is truly the most outstanding reference on the subject ever written. Since the origins of mankind, wood has played a key role in the history of humans and other living creatures, ranging from provision of life from trees giving air, heat, light, and food to nourish their bodies to structures to protect them from the elements. Wood has also played a key role in one of the world's primary religions. Nondestructive diagnostics methods have long found application in medi­ cal practice for examination of the human body in order to detect life­ threatening abnormalities and permit diagnosis to extend life. Nondestructive testing has been used for many years to insure the safety of machinery, air­ craft, railroads, tunnels, buildings and many other structures. Therefore, it is timely for a treatise, like the present one, to be written describing how wood can be characterized without employing destructive test methods. Since wood is so valuable to mankind, it is important to know the latest methods to nondestructively characterize wood for all practical applications.

Dendrochronology and wood anatomy developed for decades as two independent scientific fields. It was only in the last decade that it was made clear that the dimension of time is the fourth dimension for both sciences and that it was demonstrated that wood anatomy and dendrochronology are perfect partners. The main aim of this book is to show the hidden ecological richness in stems and roots from trees, shrubs and herbs. It should encourage researchers to consider the anatomic microcosm of wood plants and use it as a retrospective source of information, solving problems related to ecophysiology, competition, site conditions, population biology, earth science, wood quality and even human history.

This atlas presents the information on fiber identification necessary for a fiber analyst in the field of pulp and paper. The book discusses the structure of the raw materials and the features used for the species identification in pulp. It describes the identification of 117 fiber species. Of these, 83 are wood fibers and 34 are of nonwood origin. The tree species are from all five continents, 29 species from Eurasia, 38 from North America, and 16 from the southern hemisphere and the tropics. Informative micrographs, identification tables, and distribution maps help the species differentiation.This richly illustrated book can be recommended to everyone interested in fiber identification.

Here are two physicists looking over the fence of physics, getting thrilled by the life and growth of trees, taking an altogether different, exciting view of wood: trees produce wood for their own benefit. They do not live for the benefit of man who builds his world using wood as a raw material. Timber is revealed in a different light, and the reader is taught to stop thinking of it in terms of defective beams and boards. Wood only fails as a part of the living tree. To us, the tree and wood biologists, this new definition is a real, inspiring challenge, which is just what Kubler and Mattheck intended it to be. Their answers may seem too simple or little logical to some of us; but the authors are not at a loss for sound and solid arguments. Their field studies prove the incredible, their hypotheses makes us want to get to the bottom of the un­ proven unbelievable. The authors' answers and arguments are bold and cour­ ageous. They arouse our curiosity and force us to fathom the facts. It seems as if Kubler and Mattheck wanted to trick us into believing that trees only live and react following mechanical rules and strategies. To tell the truth, that was what I first suspected the authors of: but I was wrong.

In its broadest sense, and according to the traditional conception, wood chemistry is a comprehensive discipline, ranging from fundamental studies to practical applications. The manifold constituents, located in different morphological regions in the wood, results in an extreme complexity of wood chemistry. Ever more sophisticated endeavors needing fundamental studies and advanced analytical methods are necessary in order to delve deeper into various problems in pulping and papermaking. Gradually, new, improved ana­ lytical methods, originally developed for research purposes, are currently replacing many of the old "routine" methods in practical applications. Because of the expanse of the subject, an attempt to write a book of this size about analytical methods seems, perhaps, too ambitious. Of course, a whole book series of several volumes would be necessary to cover this topic completely. However, there is undoubtedly a need for a more condensed presentation which does not go into experimental details, but is limited to the basic principles of the analytical methods and illustrates their applica­ tions. The emphasis is on more advanced and potential methods, and partic­ ularly on those based on different types of spectroscopy and chromatography.

“On making many books there is no end” but we trust that no excuse is needed for the present work. The subject of cellulose chemistry is among the simplest of studies, but the important advances of recent years have clarified it to such an extent that we feel the time is ripe for publishing a relatively simple book which may act as a guide to younger chemists who are entering those branches of our great industries which are concerned with cellulose. J.T. Marsh and F.C. Wood (1939) An Introduction to the Chemistry of Cellulose Recent progress in crystalline polysaccharide structure determination and the publication of numerous models of cellulose and cellulose derivatives by improved methods made a critical and up-to-date survey of structures and characterization of cellulose possible and necessary. Structural evaluations by refined experimental and computer-aided modeling represent the prerequisite for many research and testing areas of cellulosic materials, e.g., for establishing structure–property relationships (tensile strength, sorption, solubility , etc.), chemical reactivity and derivatization as well as the composition of cell wall materials and the orientation of microfibrils in cellulose fibers. Modern materials science needs tailored materials, linked to the structure for improvements and for new developments. The active species for enantiomeric separation in gel permeation chromatography columns are, e.g., microcrystalline cellulose derivative beads of a particular structure, which produce optimal results.

This book is not concerned directly with wood identification, although ability to recognize the wood features discussed in the preceding chapters is essential for work in wood identification. The present chapter is concerned with how wood characters have been and can be used in taxonomic and phylogenetic studies - and also which wood characters are likely or not likely to be useful, in general. In wood identification, a match of an unknown wood with known woods is usually attempted. In systematic application of wood data, similari­ ties and differences among species, genera, and families are assessed ( usually, today, in terms of a cladistic analysis). One should be especially cautious in interpreting relation between taxa the woods of which have attained similar evolutionary levels. This possibility is a very real one, because so many wood features have evolved similarly in phylads that are not closely related to each other. For example, storied wood structure has been attained in a number of phylads independently. By itself storied wood structure cannot be used as an indicator of relationship between two families, but a cladogram ( using a range of phyletically reliable features) might demoo­ strate that two families acquired storied structure before divergence ( a synapo­ morphy) and thereby a strong case for relationship of the two families is made.

The first edition of this book was the first to provide an integrated description of sap ascension from an anatomical and functional point of view. The second edition opens with the three-dimensional aspects of wood anatomy. The cohesion-tension theory and new evidence are introduced in response to recent controversies over the mechanism of sap ascent in plants. The physiology, anatomy and biophysics of xylem dysfunction are discussed and new insights into hydraulic architecture are reviewed with special emphasis on physiological limits on maximum transpiration and how hydraulic architecture limits gas exchange, carbon gain and growth of plants. The text concludes with a description of xylem failure and pathology. The book highlights fascinating areas of current research with the aim to stimulate more work in the future.

As in other scientific fields, the importance of boundary areas in wood research, such as that between lignin chemistry and hemicellulose chemis- try, continues to increase. Although the utilization of individual wood components has advanced to an appreciable extent, research into oligo- merie or polymerie compounds of two or more different components has made little progress. By contrast, in other fields, glycoproteins and pro te- oglycans have been found to form biochemical active centers in enzymes and microbes. The association between lignin and carbohydrates in lignified plants was first recognized in 1866. However, research has advanced slowly because of difficulty in the isolation and determination of wood glycocon- jugates, whieh likely have an important influence on the formation of wood, pulping behavior, pulp quality and digestibility by ruminants. Most plants contain both hydrophilie polysaccharides and hydrophobie lignins in their tissues.Lignins have been recognized to not only give mechanieal strength or rigidity to a tree or wood, but also to prevent invasion by fungi, and provide cell wall material, especially in the tracheids and vessels that deliver water extracted from the soil to the top of woody plants. How- ever, in trees, lignins have been found to interact with the polysaccharides, partieularly hemicelluloses, with whieh they coexist, leading to the forma- tion of another chemical component, a kind of glycoconjugate. Therefore, it is necessary to inc1ude lignin or p-hydroxycinnamie acids in any discus- sion on wood hemieelluloses.

This book on the Nondestructive Characterization and Imaging of Wood by Professor Voichita Bucur is truly the most outstanding reference on the subject ever written. Since the origins of mankind, wood has played a key role in the history of humans and other living creatures, ranging from provision of life from trees giving air, heat, light, and food to nourish their bodies to structures to protect them from the elements. Wood has also played a key role in one of the world's primary religions. Nondestructive diagnostics methods have long found application in medi­ cal practice for examination of the human body in order to detect life­ threatening abnormalities and permit diagnosis to extend life. Nondestructive testing has been used for many years to insure the safety of machinery, air­ craft, railroads, tunnels, buildings and many other structures. Therefore, it is timely for a treatise, like the present one, to be written describing how wood can be characterized without employing destructive test methods. Since wood is so valuable to mankind, it is important to know the latest methods to nondestructively characterize wood for all practical applications.

Dendrochronology and wood anatomy developed for decades as two independent scientific fields. It was only in the last decade that it was made clear that the dimension of time is the fourth dimension for both sciences and that it was demonstrated that wood anatomy and dendrochronology are perfect partners. The main aim of this book is to show the hidden ecological richness in stems and roots from trees, shrubs and herbs. It should encourage researchers to consider the anatomic microcosm of wood plants and use it as a retrospective source of information, solving problems related to ecophysiology, competition, site conditions, population biology, earth science, wood quality and even human history.

This atlas presents the information on fiber identification necessary for a fiber analyst in the field of pulp and paper. The book discusses the structure of the raw materials and the features used for the species identification in pulp. It describes the identification of 117 fiber species. Of these, 83 are wood fibers and 34 are of nonwood origin. The tree species are from all five continents, 29 species from Eurasia, 38 from North America, and 16 from the southern hemisphere and the tropics. Informative micrographs, identification tables, and distribution maps help the species differentiation.This richly illustrated book can be recommended to everyone interested in fiber identification.

In its broadest sense, and according to the traditional conception, wood chemistry is a comprehensive discipline, ranging from fundamental studies to practical applications. The manifold constituents, located in different morphological regions in the wood, results in an extreme complexity of wood chemistry. Ever more sophisticated endeavors needing fundamental studies and advanced analytical methods are necessary in order to delve deeper into various problems in pulping and papermaking. Gradually, new, improved ana­ lytical methods, originally developed for research purposes, are currently replacing many of the old "routine" methods in practical applications. Because of the expanse of the subject, an attempt to write a book of this size about analytical methods seems, perhaps, too ambitious. Of course, a whole book series of several volumes would be necessary to cover this topic completely. However, there is undoubtedly a need for a more condensed presentation which does not go into experimental details, but is limited to the basic principles of the analytical methods and illustrates their applica­ tions. The emphasis is on more advanced and potential methods, and partic­ ularly on those based on different types of spectroscopy and chromatography.

“On making many books there is no end” but we trust that no excuse is needed for the present work. The subject of cellulose chemistry is among the simplest of studies, but the important advances of recent years have clarified it to such an extent that we feel the time is ripe for publishing a relatively simple book which may act as a guide to younger chemists who are entering those branches of our great industries which are concerned with cellulose. J.T. Marsh and F.C. Wood (1939) An Introduction to the Chemistry of Cellulose Recent progress in crystalline polysaccharide structure determination and the publication of numerous models of cellulose and cellulose derivatives by improved methods made a critical and up-to-date survey of structures and characterization of cellulose possible and necessary. Structural evaluations by refined experimental and computer-aided modeling represent the prerequisite for many research and testing areas of cellulosic materials, e.g., for establishing structure–property relationships (tensile strength, sorption, solubility , etc.), chemical reactivity and derivatization as well as the composition of cell wall materials and the orientation of microfibrils in cellulose fibers. Modern materials science needs tailored materials, linked to the structure for improvements and for new developments. The active species for enantiomeric separation in gel permeation chromatography columns are, e.g., microcrystalline cellulose derivative beads of a particular structure, which produce optimal results.

The book is a fundamental reference source on reaction wood for wood scientists and technologists, plant biologists, silviculturists, forest ecologists, and anyone involved in the growing of trees and the processing of wood. It brings together our current understanding of all aspects of reaction wood, and is the first book to discuss both compression wood and tension wood.Trees produce reaction wood to maintain the vertical orientation of their stems and the optimum angle of each branch. They achieve this by laying down fibre cell walls in which differences in physical and chemical structure from those of normal fibres are expressed as differential stresses across the stem or branch. This process, while of obvious value for the survival of the tree, causes serious problems for the utilisation of timber. Timber derived from trees containing significant amounts of reaction wood is subject to dimensional instability on drying, causing twisting, bending and splitting. It is also difficult to work as timber, and for the pulp and paper industry the cost of removing the increased amount of lignin in compression wood is substantial. This has both practical and economic consequences for industry.Understanding the factors controlling reaction wood formation and its effect on wood structure is therefore fundamental to our understanding of the adaptation of trees to their environment and to the sustainable use of wood.The topics covered include:-Morphology, anatomy and ultrastructure of reaction wood-Cell-wall polymers in reaction wood and their biosynthesis-Changes in tree proteomes during reaction wood formation-The biomechanical action and biological functions of reaction wood- Physical and mechanical properties of reaction wood from the scale of cell walls to planks-The detection and characterisation of compression wood-Effects of reaction wood on the performance of wood and wood-basedproducts- Commercial implications of reaction wood and the influence of forest management on its formation

The oil crisis during the 1970s turned interest towards the utilization of renewable resources and towards lignocellulosics in particular. The 1970s were also the cradle period of biotechnology, and the years when biotechnical utilization of lignocellulosic waste from agriculture and forestry gained priori­ ty. This was a logical conclusion since one of nature's most important biologi­ cal reactions is the conversion of wood and other lignocellulosic materials to carbon dioxide, water and humic substances. However, while biotechnology in other areas like medicine and pharmacology concerned production of expen­ sive products on a small scale, biotechnical utilization and conversion of ligno­ cellulosics meant production of inexpensive products on a large scale. Biotechnical utilization of lignocellulosic materials is therefore a very difficult task, and the commercial utilization of this technology has not progressed as rapidly as one would have desired. One reason for this was the lack of basic knowledge of enzyme mechanisms involved in the degradation and conversion of wood, other lignocellulosics and their individual components. There are also risks associated with initiating a technical development before a stable platform of knowledge is available. Several of the projects started with en­ thusiasm have therefore suffered some loss of interest. Also contributing to this failing interest is the fact that the oil crisis at the time was not a real one. At present, nobody predicts a rapid exhaustion of the oil resources and fuel production from lignocellulosics is no longer a high priority.

At present, no single book adequately covers a basic understanding of wood book satisfies the need for such a work. It describes drying in practice. This the fundamental basis of kiln-drying technology, to enable forest companies to imFrove their drying operations as high-quality timbers become scarcer and of yesteryear can no longer be tolerated. Adaptive the wasteful practices is no longer good enough. Innovations change based on past experience of the material being dried and the processes require a sound understanding of drying. Newer techniques, such as the use of ultrahigh temperature sea­ soning and superheated steam under vacuum, require an even greater depth of physical understanding for these methods to be used effectively and economically. book provides a description of modern ideas about wood structure, This moisture movement and stress development, from which models of the drying process are developed to give the kiln operator important information about the course of drying under specified conditions, and thus a means is compared with practice wherever for rational process improvement. Theory possible.

Progress in wood chemistry has been related mainly to chemical wood pulping and bleaching and chemical utilization of wood and wood extractives. Meth­ ods of wood analysis were developed by Schorger (proximate analysis in 1917) and Dore (summative analysis in 1919), and standard methods based on Schorger's method, e.g., TAPPI standards (Technical Association of the Pulp and Paper Industry), have been widely used for chemical analysis of woods in many countries. Thus it is generally known that wood is composed of about 50% cellulose, 20-35% of lignin, 15-25% of hemicelluloses, and variable amounts of extractives. Chemical characterization and efficient utilization of these wood components have been studied in laboratories of wood chemistry and technology in universities and government institutions. In the last decade, biochemistry and molecular biology of microorganisms, animals, and plants have greatly progressed. At the same time wood has been recognized as a unique renewable ecomaterial produced by trees using solar energy. In addition, many desirable properties of wood and wood components as biomaterial that affects physiology and psychology in humans have recently attracted attention.

This book has a similar subject content to the author's previous Flow in Wood but with substantial updating due to the abundance of research in the wood science field since 1971. Several different concepts have been introduced, particularly in regard to wood-moisture relation­ ships. The role of water potential in the equilibria between wood and its humid and moist environments is considered. Two theories are introduced to explain the nonisothermal transport of bound water in the steady and unsteady states. As in the former text, the wood-. structure relationship is emphasized . . The author is especially grateful to Dr. C. Skaar for his careful and critical review of much of the manuscript and for the productive dis­ cussions of many of the concepts. Dr. T. E. Timell, the series editor, rendered major assistance in the preparation of Chap. 2 and in his editing of the manuscript. The author wishes to thank Dr. W. A. Cote, Mr. A. C. Day, and Mr. J. J. McKeon for providing electron micro­ graphs, Mr. G. A. Snyder for his photography of much of the art work, Dr. C. H. de Zeeuw for his advice in the field of wood anatomy, and Ms. Mary M. Siau for her careful rendition of the art work. Apprecia­ tion is extended to Miss Judy A. Barton and Mrs. Stephanie V. Micale for their work in typing and checking the manuscript. Mr. J. A.

The trend in forestry is toward shorter rotations and more complete utiliza­ tion of trees. The reasons are: (1) financial pressures to obtain rapid returns on the forestry investment made possible by an earlier harvest; (2) enforced harvest of young plantations to maintain a continuing supply of cellulose for mills where wood shortages are experienced; (3) thinning young plantations, both because they were planted too densely initially and because thinning is done where long rotation quality trees are the forestry goal; (4) more intensive utilization is being done using tops and small diameter trees; and (5) there is interest in using young (juvenile) wood for special products because of its unique characteristics and the development of new technologies. The largest present-day source of conifer juvenile wood is from thinnings of plantations where millions of hectares of pine were planted too densely. Because of the better growth rate resulting from improved silviculture and good genetic stock, plantations will need to be thinned heavily. As a result of this trend, young wood makes up an increasingly larger proportion of the total conifer wood supply each year. Large amounts of juvenile wood from hard­ woods are also currently available, especially in the tropics and subtropics, because of the fast growth rate of the species used, which results in shorter rotations and ess~ntially all juvenile wood.

Why prepare a treatise on Heartwood and Tree Exudates? Why consider both topics together? What approach should be taken in their treatment? The exudates were one of the earliest items of trade between family, tribal, and racial groupings in prehistoric times. They became used extensively as items for the manufacture of implements and as commercial goods for illumination, for cosmetic, religious and magical purposes. Later heartwood from various trees entered intra­ and international trade for prestigious and religious buildings (when cedars were used), for the furniture (e.g., ebony, mahogany) of the nobility, for boats and vehicles. Consideration of their relevance to anthropology, and to the origin of technological developments in different primitive cultures, would satisfy a personal life-long interest. Attention to such a topic is urgently needed now that the development and destruction of land and forests is increasing and wiping out the traces of earlier people to meet the demands of the rapidly enlarging populations of today. The latter represents an even more urgent need. Increasingly, mankind will depend on renewable,resources produced at low energy cost. Forest products are one of these and the greater demands for them will require their growth and utilization with reduced loss and waste.

The vascular tissue of higher plants has been an object of continuous detailed study since the invention of the light microscope. As relevant new physical, chemical and biochemical techniques and concepts have appeared over the years, they have regularly and immediately been applied to this field of enquiry. The reasons are not far to seek. Vascular tissue provides the long-distance transport system for water and nutrients within the plant, and an understanding of the structure and development of the pathways within it is essential for an under- standing of growth in all higher plants, including crop plants. Moreover, parts of the vascular tissue - the whole of the xylem and the fibers of the proble- have been, and still are, in high demand commercially for their unique properties and as the only renewable structural material on earth. There are, in addition, more subtle ways in which xylogenesis, particularly as it allows the development of tree species, contributes to the environment. A few years ago, while walking in the foothills of the Pyrenees, I found all this expressed more elegantly than I can express it, in a plea carved in wood at the entrance to a forest: Homme!!Je suis la chaleur de ton foyer par les froids nuits d'hiver, l'ombrage ami lorsque brule Ie soleil d'ete, l'eau des rivieres et des sources. Je suis la charpente de ta maison, la planche de ta table.

Wood is formed in an essentially water-saturated environment in the living tree, and the cell wall remains in this state until the water flow from the roots is interrupted, such as by felling the tree. The wood then begins to lose most of its moisture by drying, resulting in changes in most of its physical properties. These changes, and their relationship to the environment to which the wood is subsequently ex­ posed, are the subject of this book. The text consists of six chapters. The first chapter discusses cer­ tain empirical relationships between wood and water, methods of measuring wood moisture content, factors which affect its equilib­ rium moisture content, and the effect of moisture content on wood strength. The second chapter treats the thermodynamics of moisture sorption by wood, inc1uding enthalpy, entropy, and free energy changes. The third chapter discusses some of the theories which have been proposed to explain the sorption isotherms for hygroscopic ma­ terials such aswood. Chapter 4 considers hygroexpansion or the shrinking and swelling of wood associated with moisture change. Chapter 5 is concerned with how moisture moves through the cell wall of wood in response to both moisture and temperature gradients. The sixth and final chapter discusses the theoretical and practical aspects of the electrical resistance and dielectric properties of wood, in­ c1uding the principles involved in their application in electrical moisture meters.

It is widely recognized that spiral grain in trees severely reduces the value of sawn timber through warping and loss of strength, and that it also causes problems for other wood uses as diverse as transmission poles or plywood. Yet, paradoxically, there are highly valued grain patterns including wavy and interlocked grain, whose origins in the cambium invite direct comparison with those of spiral grain, so that many authorities believe them to be related phenomena. In recent years this concept has prompted extensive research into the anatomy, genetics, and physiology of all such grain patterns in wood. As a result it has become apparent that tree cambia provide excellent systems through which to study the origins of stem polarity and the complex processes of morphogenetic control in plants. Beside these and other pressing topics for research, the book examines methods of measuring grain deviations, and considers their influence on wood properties, on the economics of timber production, and on wood manufacturing.

The structural complexity of lignin has continually challenged the in­ genuity of researchers to develop suitable methods for its charac­ terization prior to and following a wide variety of chemical, biologi­ cal, and physical treatments. Initially, activity along these lines was fueled by a desire to interpret technical delignification (Le. , pulping) processes in terms of accompanying structural changes in the lignin. Subsequently, increasingly wide ranging, in-depth investigations on the structure and reactivity of lignin exposed the inadequacy of many of the methods currently in use and underscored the ever-continuing need to develop new methods capable of solving the unique analytical problems associated with lignin. Characteristically, such methods should be selective, sensitive, suitable for quantitative measurements, and capable of being applied directly to, and without destruction of, the lignin or lignocellulose sample. One notable example of the head­ way being made in reaching this objective is the relatively recent devel­ opment and refinement of methods based on the use of sophisticated instrumentation, e. g. , lH_ and 13C-NMR spectroscopy. Although the utility of many of these and other recently developed methods de­ scribed in this book has yet to be fully and satisfactorily exploited, we believe that progress already made in this direction will continue and most likely accelerate. The decision to produce this book was prompted mainly by the acknowledged need for an up-to-date, single source compilation of lignin methodology. Hitherto, this need was, in part, satisfied by B. L.

Wood is the usual end product of a forestry operation. Because of its importance, numerous studies have been made relative to wood prop­ erties, the causes of wood variation, and how best to develop wood for desired products. There is voluminous literature related to these subjects, but it is neither well known nor appreciated by foresters because the publications are often not available or are not well understood by the forester or by those who use the wood. Frequently, the literature is confusing and contradictory, making it difficult for the nonspecialist to use what information is available. In order to produce and use wood efficiently, the variation pat­ terns within trees, among trees within species, and among species must be understood. This also requires some knowledge of the causes of variation and the effects of different wood properties upon utiliza­ tion. The information about variation patterns, their causes, and con­ trol and effect upon the product must be known by the tree grower, the tree breeder, and the tree harvester as well as by those who ultimately convert wood into a final, salable product.