The English Oak Quercus Robur is deep-rooted and most common on heavy wet soils. It is a lowland tree found in South West England as high as 400m (1320’) but in the highlands of Scotland they rarely occur above 200m (660’).
The mature English Oak tree supports a larger number of different life forms than any other British tree. This includes up to 284 species of insect. Up to 324 taxa (species, sub-species or ecologically distinct varieties) of lichens, growing on the bark of any one tree.
The vast array of insect life found in the Oak tree means that this tree of all British trees supplies the most food for birds such as Tits and Tree Creepers.
When acorns loosen in their cups, the oak tree provides a harvest for many wild creatures. In ancient times the wild boar, but now, jays, pigeons, pheasants, ducks, squirrels, mice, badgers, deer and pigs feast on acorns in the autumn.
The acorns dormancy is not deep; many begin to germinate by putting out a root very soon after falling, though a shoot is not produced until the spring. The seedlings develop a substantial tap root. They can survive the loss of some early shoots, however, they are less tolerant of shade if is it combined with other damaging influences such as caterpillar defoliation or attacks of the oak mildew fungus (Microspaera Alphitoides).
Under sheltered conditions and deep soil, oaks can grow into magnificent trees 40m (130ft) or more in height. The tallest trees are not, however, particularly old – probably no more than about 300 years, Most really ancient oaks, which are invariably hollow, are not so tall, they generally occur in places that were ancient wood pastures, where widely spaced trees were pollarded for centuries to provide timber and firewood.
The typical development of the tree includes a period of quite rapid growth for around 80-120 years, followed by a gradual slowing down. It progressed from a young, smooth, silvery brown barked sapling to a huge, rugged, hollow hulk, with rough, hard, deeply fissured bark. After about 250-350 years, decline sets in. Branches die back, and the diameter growth slows right down. A study of Wistman’s Wood high on Dartmoor showed that the Oak trees measured in 1621, are the same height today.
The oak comes into leaf very late, often not until mid May. Acorns are not produced until the tree is about 7 years old with seed production reaching a maximum between 80-120 years. Oaks tend to fruit very abundantly only in mast years, which occur every 4-7 years. In other years, fewer acorns are produced, and in some none at all.