One of the oldest construction materials is wood which, technically speaking, belongs to the group of polymer matrix composites; one which is conveniently and expertly produced by Nature. Due to its organic cell-type structure, the density of wood remains modest. Thus, as its strength and stiffness can - in certain cases - attain remarkable values, its levels of specific strength and stiffness (absolute strength or stiffness divided by density) can reach magnitudes which are competitive with those of other construction materials. It is demonstrated, for instance, that the specific strength of wood in the axial direction can exceed those of low-carbon steel and concrete. Its specific stiffness can also be comparable to those of aluminum alloys and low-carbon steels, and is better than that of concrete. In constructional design, especially in the dimensioning of supports, the values of specific strength and stiffness are of utmost importance.

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.