The Heart of the Oak: Enduring and Majestic

Large oak tree provides shade near a pond on a misty morning
Oaks have often been referred to as generous, hospitable, scholarly, surveyors and long-lived.

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The mighty oak is truly a remarkable tree. Oaks have sustained humans for more than 6,000 years. Oaks have often been referred to as generous, hospitable, scholarly, surveyors, and long-lived.

From Vancouver to Caracas, from Miami to Dublin, from Lisbon to Jakarta, and from Seoul to Tokyo there are about 425 species of oaks. Their lineage dates back some 65 million years. They are genetically rich and an incredibly flexible genus surviving geologic upheavals and many climate changes.

One Tough Tree

Oaks can tolerate fire, the onslaught of repeated insect infestations, and prolonged periods of drought. And some oaks can live well past 1,000 years. Within the life of an average oak tree, it will grow over three million acorns — its seeds. A mature tree will support over 500 million living root tips.

Some oaks are deciduous while others are evergreen. They rely upon wind, not insects or birds to spread their pollen, which is an ancient characteristic more common to the conifers rather than the angiosperms.

Oaks and jays have evolved together. These birds depend upon acorns as a food source. They cache them throughout the forest. Oaks depend upon jays to disseminate their seeds. Those acorns that aren’t eaten eventually become trees.

A mature oak tree can grow 121 feet tall supporting a crown 121 feet wide and provide habitat for over 5,000 species of plants, animals, insects, fungus, and bacteria. This includes 40 species of wasps — cynipines — that create ping pong ball-sized growths or galls on oak branches. These wasps have been associated with oaks for the past 30 million years.

Six thousand years ago foresters discovered that when the oak tree is felled, its root system responds by shooting up four or sometimes six new trees from the base of the cut stump. This form of natural regeneration is called coppice. Every five to 25 years it yields a new crop of trees.

The founding forestry textbook “Sylva” was written by John Evelyn in 1664 and is focused on oak trees. Essentially, foresters were trained to be in tune with the health and shape of trees just as a physician is to that of the human body.

For thousands of years, people and cultures have depended upon oaks and their acorns as their staple food source. In Tunisia, oak means "meal-bearing tree." People from Iraq to Korea to the Native Americans of California all collected acorns, soaked them, mashed them, and made cakes or soups. One mature white oak tree can throw 302 to 500 pounds of acorns per year. Records from the early 20th century show that Iraqis consumed more than 30 tons of this cake each year.

Everything from roads to ink

Human beings learned from the woods around them. Oak forests made roadways, frames, doors, palisades, barrels, coffins, hinges, boats, tanning, and ink.

Fire made human civilization possible. Charcoal — lumps of almost pure carbon — was the fuel that ended the Stone Age, enabling the smelting of bronze found in iron. In comparison to wood, charcoal is smokeless, it burns more efficiently and it burns hotter. It took, however, 8 pounds of oak to make 1 pound of charcoal, an 8-to-1 ratio.

The role of oak was pivotal in boat building. The Vikings and their legendary longships were the finest, sleekest crafts ever created. Whether sailing of rowing these boats carrying 40 tons was able to arrive on foreign shores unheralded.

Later, Western European countries built huge oak boats weighing the equivalent of a 40-room wooden mansion. They could carry 397 tons of cargo. Those boats required wood from at least 62 acres of mature oak forests.

Check out this roof

The greatest work of art from the European Middle Ages was the 594 tonnes of oak that framed the roof of Westminster Hall. Architects, engineers, and scholars marvel at Hugh Herland’s use of joints, scarf joints, and mortise-and-tenon joints in the posts, beams, and arches created for King Richard II in 1397.

Ink derived from oak galls was used by Leonardo da Vinci in his notebooks, by Bach in his scores, and by van Gogh in his drawings.

Today oak is used by mankind for furniture, flooring, timber frames, and basketry, and the nose of every space shuttle is coated with cork, from the bark of the cork-oak tree, because it provides unparalleled heat-resistant protection for the shuttle’s re-entry to Earth’s atmosphere.

The compliment “you have a heart of an oak” is a splendid tribute to this exquisite genus of trees.