plant tissue
  • Wood as a material
  • Structure and composition
  • Macrostructure
  • Earlywood, latewood, and pores
  • Heartwood and sapwood
  • Rays and resin canals
  • Radial and tangential sections
  • Microstructure
  • Ultrastructure and chemical composition
  • Variation of structure and defects
  • Properties of wood
  • Sensory characteristics
  • Density and specific gravity
  • Hygroscopicity
  • Shrinkage and swelling
  • Mechanical properties
  • Thermal properties
  • Electric properties
  • Acoustic properties
  • Degradation
  • Bark and bark products
  • Wood

    plant tissue

    Wood, the principal strengthening and nutrient-conducting tissue of trees and other plants and one of the most abundant and versatile natural materials. Produced by many botanical species, including both gymnosperms and angiosperms, wood is available in various colours and grain patterns. It is strong in relation to its weight, is insulating to heat and electricity, and has desirable acoustic properties. Furthermore, it imparts a feeling of “warmth” not possessed by competing materials such as metals or stone, and it is relatively easily worked. As a material, wood has been in service since humans appeared on Earth. Today, in spite of technological advancement and competition from metals, plastics, cement, and other materials, wood maintains a place in most of its traditional roles, and its serviceability is expanding through new uses. In addition to well-known products such as lumber, furniture, and plywood, wood is the raw material for wood-based panels, pulp and paper, and many chemical products. Finally, wood is still an important fuel in much of the world.

  • Production and consumption of wood

    In botanical terms, wood is part of the system that conveys water and dissolved minerals from the roots to the rest of the plant, stores food created by photosynthesis, and furnishes mechanical support. It is produced by an estimated 25,000 to 30,000 species of plants, including herbaceous ones, though only 3,000 to 4,000 species produce wood that is suitable for use as a material. Wood-producing forest trees and other woody plants are of two categories: gymnosperms and angiosperms. Gymnosperms, or cone-bearing trees, produce softwoods, such as pine and spruce, and angiosperms produce temperate and tropical hardwoods, such as oak, beech, teak, and balsa. It should be noted that the distinction implied by hardwood and softwood is not true in all cases. Some hardwoods—e.g., balsa—are softer than some softwoods—e.g., yew.

    Wood is a material of great economic importance. It is found throughout the world and can be sustainably managed as a renewable resource—in contrast to coal, ores, and petroleum, which are gradually exhausted. By means of its harvesting in forests, its transportation, its processing in workshops and industries, and its trade and use, wood provides jobs and supports economic development and, in some countries, basic subsistence. Indicative of this importance is the continued high demand for wood and wood products.

    On a weight basis, the consumption of wood exceeds by far that of other materials. More than half of roundwood (log) production is consumed as fuel, mainly in less-developed countries. Production of paper and paperboard has shown the most rapid increase among wood products; this trend is expected to continue as consumption per person in the less-developed countries approaches that in the developed nations. Rising world population is the driving force of increasing consumption of wood and consequent deforestation. The depletion of many forests, especially in the tropics, makes uncertain the provision of an adequate wood supply to satisfy the anticipated need. Efforts to stop the reduction of Earth’s forest cover and increase the productivity of existing forests, establishment of extensive reforestation programs and plantations of fast-growing tree species, recycling of paper, and improved utilization of wood through research could ease the problem of wood supply and help to lessen the environmental toll of the lumber industry.

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