Beeches got old, senile and then fell down

IN THE part of the country that I live in there were a number of dramatic incidents over the course of the winter when large trees came crashing down in storms, blocking roads and, in some cases, doing damage to buildings and vehicles.

In practically every case the trees that fell were large beeches and other species of tree of the same size survived.

The reason the beeches fell is that they had reached the end of their natural life-span. When the wind took them they were already dying slowly and losing the battle with invading fungi of species like ganoderma. Beeches do not have a very long life expectancy compared to other species of large tree. They tend to become “senile,” to use the technical forestry word, at around 250 years old.

There was a great upsurge in tree planting in Leinster in the 1750s and 1760s. For the first time the larger land-owners felt secure enough to plant for the following generations. This sense of security was rather misplaced in the part of Kildare that I live in because it saw fierce fighting in 1798, but by this time the trees had been planted.

The two most popular species in this area at the time were beech and lime. Neither of them is a native Irish species but both are British natives. However the planters, many of whom were members of the House of Lords in Westminster, probably failed to make this distinction. The beeches are dying of old age but the limes are not.

Our knowledge of the life expectancy of the different species of tree is far from complete and this causes experts to get into arguments. But it’s certainly true that we have no idea how long a lime tree can live and there is a good reason for this.

Almost all the limes planted in Ireland are hybrids between the broad-leaved lime and the small-leaved lime. These hybrids may occasionally occur naturally but the ones planted by land-owners in the eighteenth century were bred artificially by gardeners.

The hybrid was only developed shortly before the first Irish trees were planted. It was a novelty and rather fashionable. So the very oldest examples of limes in the country are probably less than 300 and show no signs of senility. This is probably a very long-lived tree but we may have to wait a while, perhaps several more centuries, to find out exactly how long.

MANY hybrids live longer that their parents. Both parents of the hybrid lime are rather rare native trees in England and Wales. And it seems that both of them have the ability to lead very long and healthy lives.

The small-leaved lime, in particular, can reach an extraordinary age. Archaeological work at an early Viking site in England has established that the small-leaved limes still growing there were in position before the Vikings arrived. This gives the trees a minimum age of 1200 years.

The only native tree in Britain or Ireland that can beat this is the yew. It’s now accepted that yews can live for about 2000 years and experts are open to the possibility that they may be able to reach twice this age. All very old yew trees are hollow and this makes them hard to age accurately.

There are some big, old yew trees in Ireland but none that have been authenticated as truly ancient, which I would classify as over 1000. But there are several in England and one in Scotland that are undoubtedly between 1000 and 2000 years old.

This contrasts with about 325 for oak and a mere 250 to 260 for the beeches that have been crashing to the ground in Leinster over the past few months.

[e-mail]