For a small forest see forest. For wood as goods see wood. For other uses, see wood (disambiguation), wood (disambiguation) or heartwood (disambiguation).
Wood is a porous and fibrous structural fabric that occurs in the stems and roots of trees and other wood plants. It is an organic material – a natural composite of tension-resistant cellulose fibers, embedded in a lignin matrix that resists compression. Wood is sometimes only defined as a secondary xylem in the stems of trees, or is more generally defined to include the same type of tissue elsewhere, such as in the roots of trees or shrubs. [Citation required] In a living tree, it performs a support function that enables wood plants to grow up or stand up independently. It also transports water and nutrients between the leaves, other growing tissues and the roots. Wood can also refer to other plant materials with comparable properties, as well as material made from wood or wood shavings or fibers.
Wood has been used as a fuel as a building material for the manufacture of tools and weapons, furniture and paper for thousands of years. More recently, it has been developed as a raw material for the production of purified cellulose and its derivatives such as cellophane and cellulose acetate.
As of 2005, the growing forest population worldwide was around 434 billion cubic meters, 47% of which were commercial. As abundant, climate-neutral renewable raw materials, wood-based materials were of great interest as a renewable energy source. In 1991, around 3.5 billion cubic meters of wood were harvested. The dominant uses were furniture and building construction.
A 2011 discovery in the Canadian province of New Brunswick produced the earliest known plants that had grown wood around 395 to 400 million years ago.
Wood can be dated by carbon dating and, in some species, by dendrochronology to determine when a wooden object was created.
Humans have been using wood for many purposes for thousands of years, including as fuel or as a building material for the manufacture of houses, tools, weapons, furniture, packaging, works of art and paper. Known wooden constructions date back ten thousand years. Buildings like the European Neolithic longhouse consisted mainly of wood.
The recent use of wood has been improved by the addition of steel and bronze to the building.
The tree ring widths and isotope frequencies, which vary from year to year, provide information on the prevailing climate at the time a tree was felled.