Nature Explored

by Chris Dunford








English Oak

The most important tree in the Wood

Oaks are a member of the Beech family. Worldwide ther are 600 types of oak in several genera, all native to the Northern hemisphere. There are both broadleaved and evergreen varieties.

The Pedunculate or English oak is a broadleaf deciduous tree of the genus Quercus. Oak tree in field in Spring
Oak tree in a field in Spring
It Grows 15 to 40 m high and can live 800 - 1000+ years.

Leaves appear in late Spring - usually in May. They are large, dark green with deep lobes and smooth edges. Catkins appear in May or June. Both sexes are found on the same tree. Oaks are wind pollinated. The acorns, which are actually a nut, are dispersed by wildlife.

The tree takes 20 to 50 years before it starts producing acorns. When the tree is between 70 and 80 years old it produces tens of thousands of acorns per year. Only 1 in 10000 will find the right conditions to germinate. The amount produced varies greatly every year.

Squirrels, mice, pigeons, ducks, deer, bears and pigs all eat acorns. Acorns take six months to develop and fall off the cup in October.

Oaks are happy in most soils except Marsh and Light Chalky areas. They are common in heavy wet soils.

Oak is a climax vegetation in the woodlands of the Northern hemisphere. What that means is, left untouched by humans, it would be the dominant tree. Much of England was covered by oak forests before modern farming took over the land.

The Mighty Oak is the undisputed King of the Forest

They can transpire up to 50 gallons of water per day.

Oaks can respond to the stress of extended droughts by killing off some of their own branches , which shrinks their canopies. The ribbed bark of the oak
The ribbed bark of the oak

The tree supports more wildlife than any other in the Country. Over 500 invertebrates live on or in the oak. The heartwood (which is dead) is often eaten over hundreds of years by a benign fungus which will leave the tree hollow but alive and healthy.

Oak trees that are attacked by caterpillars react by stepping up the quantity of tannin and phenol produced in their leaves. It has been observed that the trees’ defence mechanisms inhibit the growth of the larvae. Tannins are bitter liquids that shrink leaf proteins and make consumption and digestion more difficult. They defend the tree against hostile environmental conditions, herbivores and pathogens.

Acorns, buds and young leaves can be highly toxic to some animals such as cows if eaten in large amounts.

Oak wood is one of the most dense naturally occurring materials, while high content of tannin makes it resistant to both fungal diseases and insects. It has a density of about 0.75 grams per cubic centimetre. For example, pine wood has a density of 0.43 grams per cubic centimetre.

Although its natural chemical defences make it highly resistant to many predators there are some diseases such as oak wilt, a lethal fungal disease, and sudden oak dieback which is a mould, that can be lethal within weeks. Sudden oak decline, first seen in 2009, is characterised by oozing fluid from lesions on the bark and can kill the tree within five years.

The timber is used for furniture and flooring as well as panelling, such as in House of Commons debating chamber. Wine, sherry, brandy and whisky all aged in oak barrels. Oak chips are used to smoke fish. Ripe acorns ready to fall in October
Ripe acorns ready to fall in October

Oak is the sacred tree of Thor, the God of thunder. It was thought to be so because many were struck by lightning.

The Major oak in Sherwood forest is 800-1000 years old and is said to have been where Robin Hood hid when evading the Sherrif of Nottingham.

The word Druid means 'oak man' and they used to burn oak in their Summer sacrifices.