News and blog Cornwall’s Ancient Trees Blog Do Ivy and Other Structures Impact Ancient Trees? Do ivy and other structures impact Ancient Trees? Most farms I have visited recently have had at least one veteran tree somewhere, and it is clear that they are an under-recorded resource in Cornwall. I recently had the please of coming across this spectacular twin-stemmed ancient ash tree near Golant. Both trunks are completely hollow – a clear indication of its great age, and each has a girth of more than 3.5m. It once formed part of a hedge bank that has since been removed, and over time will need to be managed through careful pollarding to replicate its historic management that has led to its current form. Each trunk is likely to be relatively fragile owing to their age, and the unhindered growth of large limbs would eventually cause them to collapse. This brings up two other points to discuss – whether the ivy and the treehouse in this particular tree might be impacting it. The answer in this case is probably no. Ivy – in most cases should not be cut from a tree and is an extremely valuable resource for wildlife at all times of year. Ivy doesn’t parasitise a tree any more than it does a wall! However, the ivy can become a problem for veteran trees if it grows extensively in the canopy, because it will then compete with the tree for light. This could be particularly detrimental for isolated trees where they had no competition for light as they developed. The ivy may also catch the wind of winter storms when the tree would otherwise be bare, which could feasibly be an issue for a fragile, overgrown pollard, although the resolution to this would be to carefully pollard the tree to reset it. This ash tree has some mature ivy, but it is not competing much with the canopy, and likely causes very little risk. However, its value to nature was quite clear when I visited, with several thrushes feeding on the berries, and other birds using it for cover. It will be sensible to keep an eye on the ivy in this tree, but there is no imminent need to control it. Treehouse and other structures in ancient trees – Trees are good at balance themselves as long as there are no sudden changes to their weight distribution. If they grow at an angle, the roots react to the displaced centre of gravity by growing in the direction that best supports the structure. However, this all happens very slowly, and if the addition of weight changes the centre of gravity, this can make unbalance the structure and make it more vulnerable to becoming uprooted during a storm. This is not likely to be an issue for this ash tree, as the ‘house’ is mostly supported by the additional posts. The structure may even be providing support to the tree. It is also important not to damage or puncture the bark, for example with nails, as this can allow disease into the tree, and if one area of bark has a lot of punctures, the tree will protect itself by essentially walling off that area from the rest of the tree, meaning that section will die off.