Oaks

The structural characteristics of the wood make oak one of the most versatile hardwoods, valued by many industries. The strength of oak wood is a result of the inner structure of vessels and fibers. The ring porous nature of the woody tissue results from uneven vessel growth. During the spring and summer, large vessels and fibers grow, followed by smaller vessels as the season progresses. In deciduous species, the vessels are almost non-existent and during the fall and winter are replaced by fibers. This provides distinct growth rings and adds to the structural integrity of the wood. It also provides a distinctive grain pattern when planed into thick planks for panelling and cabinetry.

In red oaks, the vessels remain open over time, allowing fluid conduction to continue. These species are used in making railroad timbers and furniture. The vessels of the white oaks become gummed up with tyloses and are more valuable for barrel staves and flooring. Casks made of oak are in high demand for fermenting wine in France and many other countries. Many of the early sailing ships used oak timbers for hulls and ribs. A famous example is Old Ironsides, a U.S. Navy frigate whose restoration used many large timbers of live oak (Q. virginiana). The destruction of the English oak (Q. robur) forests in Europe to construct the navies of the 1600s was one of the many economic incentives for colonizing the New World with its untouched expanses of hardwood forests.

The cork oak (Q. suber) is another commercially valuable species found throughout the Mediterranean region. The thick bark composed mostly of cork cells can be harvested every 10 years in early summer to provide sheets of soft, smooth cork useful in many ways. The cork cells capture air inside as they dry, making the material extremely resilient and buoyant. Cork has been used to manufacture floats, handles, stoppers, and as insulation, since it is a poor conductor of heat and sound.

Probably the most common worldwide use of oak is as fuel. Oak burns very hot, providing up to 23 million BTU per cord. Charcoal made of oak was extremely important to small local industries during the nineteenth century. Most hardwood forests are managed for fuel wood harvesting or lumber, with oaks considered the most valuable species.