It seems that one of the reasons the oak feels so quintessentially English, is that there are more ancient oaks in this country than in the rest of Europe (there are 115 in England that are wider than nine metres in circumference, compared to just 96 across the whole of the other European countries put together). The effects of the world wars and the long-term use of plantation forestry (the planting of fast-growing trees at the expense of slow-growing oak) in Europe are the main reasons for this.

But what exactly do we mean by ancient oaks? Just how old they are is hard to tell, although a tree is generally classed as ancient when it appears to have entered the final stage of its life, which for an oak tree is when it’s at least 400 years old. The usual method of determining a tree’s age – by counting its rings – doesn’t work as most are largely hollow, caused by a fungus called Fistulina hepatica. (Surprisingly though, these oak trees often continue to live long after their trunks have been hollowed.) The other method of calculating age is to measure the tree’s circumference, work out its radius and compare this to the average annual growth of an oak tree. It’s a method that can’t be completely relied on though, because growth speed can vary, as proved by the Major Oak in Sherwood Forest, which has been measured regularly since 1790. The other problem with measuring an ancient oak is that many have become divided into several trunks at the base.

Finding these oaks is less difficult, because there are many places that, thanks to their history, have held onto their ancient trees. The most important of these are our medieval deer parks. During the 13th century, it’s possible there were more than 2,500 of these dotted around the country – every nobleman wanted at least one. They were used to keep fallow deer, and the trees provided the herds with an important source of food and shelter. There aren’t nearly so many medieval deer parks in England today, but enough have remained to protect some of the oaks that have been growing there for centuries. They now account for 34.5% of England’s ancient oaks (with a further 13% in Tudor deer parks).

Outside of these parks, most other ancient oaks are found in either royal forests, wooded commons or the grounds of manor houses. Royal forests, such as Sherwood Forest, were once mostly uncultivated areas of pastureland (the word ‘forest’ once simply meant an area of land that the public were excluded from and, in fact, has nothing to do with trees), used by the king for hunting. Very few remain now, and those that do are often much more heavily planted, with their oak trees cut down or at risk from overcrowding. Only 20 of the remaining 44 royal forests are home to ancient oaks, and are where just 7.3% (and a further 4.6% in chases – areas given to noblemen for hunting) of the current population grow.

Wooded commons, on the other hand, were generally areas that the public did have access to. As a result, the trees here are often pollarded – cut off from the top to provide a source of timber – and so many haven’t survived due to overuse. Those that are still standing can be recognised by their short trunks that support a mass of larger branches above (as opposed to ‘maiden’ oaks – trees that weren’t pollarded and have a normal arrangement of branches around a tall, central trunk). Just as in deer parks, the trees here were also used as shelter for animals, this time for grazing livestock, so, apart from the pollarding, the trees were left to grow. Wooded commons are now home to 6.5% of our ancient oaks.

Many of the remaining trees – 19% in fact – can be found in the grounds and estates of manor houses built before 1600. In many cases, it’s continued private ownership that has ensured the survival of these trees. 

Protecting our ancient oaks

Oak trees support more life than any other species. They’re especially important to invertebrates and epiphytes (mosses, lichens, ferns and fungi), which in turn feed birds and other animals. It’s one of the reasons that the conservation of our ancient oaks is so important. The other, of course, is their historical importance; in Farjon’s words, they’re “monuments to our past”.

Sadly, they’re still threatened. Since the early 20th century, the planting of fast-growing forests to provide timber has been one of the biggest causes for concern. Recently though, there’s been a shift in woodland management towards preserving them, now that we better understand their importance. Nowadays, ploughing too close to their roots and keeping livestock nearby are causing a great deal of damage, as are vandalism and neglect (especially of pollarded trees, which must be continually managed so they don’t become too top heavy).

Fortunately, there are a number of people and organisations, chiefly The Woodland Trust, that are campaigning and educating on behalf of these oaks. And, at the time of his talk, Farjon was soon to advise a House of Lords committee on how best to protect them.