Felix qui potuit rerum cognoscere causas. Pub/ius Vergilius Mara Forests have long been one of mankind's most important natural re sources and not the least because forests are, if properly managed, re newable. They serve us in many different ways, but above all in pro viding us with wood, one of the most remarkable and useful of all natural materials. Reaction wood, compression wood in gymnosperms and tension wood in the arboreal angiosperms, serves the function of making it possible for trees to perform movements. In the ancient Ginkgo and in the conifers, the ability to form compression wood is of vital importance to each and every tree. Compression wood plays a crucial role in the regulation of tree form in these gymnosperms, and their arborescent habit probably depends on their ability to develop this tissue. Few forest and plantation trees are devoid of compression wood in their stem, and all of them have it in their branches. Unfortu nately, what is necessary and beneficial for the tree in this case is harmful to mankind, for compression wood is a very serious defect in both sawtimber and pulpwood. It is now almost 20 years since the last complete survey of compres sion wood was published, namely Arthur H. Westing's excellent review of this subject. My major objective in writing the present book has been to bring together in one single work everything that is currently known about compression wood.

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-based products - Commercial implications of reaction wood and the influence of forest management on its formation

Wood is the most versatile raw material available to man. It isburned as fuel, shaped into utensils, used as a structuralengineering material, converted into fibres for paper production,and put to newer uses as a source of industrial chemicals. Its quality results largely from the chemical and physicalstructure of the cell walls of its component fibres, which can bemodified in nature as the tree responds to physical environmentalstresses. Internal stresses can accumulate, which are releasedcatastrophically when the tree is felled, often rendering thetimber useless. The quality of timber as an engineering materialalso depends on the structure of the wood and the way in which ithas developed in the living tree. Tree improvement for quality cannot be carried out without anunderstanding of the biological basis underlying wood formation andstructure. This volume brings together the viewpoints of bothbiologists and physical scientists, covering the spectrum from theformation of wood to its structure and properties, and relatingthese properties to industrial use. This is a volume for researchers and professionals in plantphysiology, molecular biology and biochemistry.

With today’s ever growing economic and ecological problems, wood as a raw material takes on increasing significance as the most important renewable source of energy and as industrial feedstock for numerous products. Its chemical and anatomical structure and the excellent properties that result allow wood to be processed into the most diverse products; from logs to furniture and veneers, and from wood chippings to wooden composites and paper. The aim of this book is to review advances in research on the cellular aspects of cambial growth and wood formation in trees over recent decades. The book is divided into two major parts. The first part covers the basic process of wood biosynthesis, focusing on five major steps that are involved in this process: cell division, cell expansion, secondary cell wall formation, programmed cell death and heartwood formation. The second part of the book deals with the regulation of wood formation by endogenous and exogenous factors. On the endogenous level the emphasis is placed on two aspects: control of wood formation by phytohormones and by molecular mechanisms. Apart from endogenous factors, various exogenous effects (such as climate factors) are involved in wood formation. Due to modern microscopic as well as molecular techniques, the understanding of wood formation has progressed significantly over the last decade. Emphasizing the cellular aspects, this book first gives an overview of the basic process of wood formation, before it focuses on factors involved in the regulation of this process.