Andrew Doyle (Wicklow, Fine Gael) | Oireachtas source

I will be happy to discuss other aspects of the matter later.

Ivy is an evergreen shrub that is found growing in the wild in Ireland. It is a native species that contributes to the diversity of plants growing in many habitats, both within woodland settings and on individual trees. As a species, the native ivy has received criticism in some quarters. Ivy uses trees for support and to climb and takes no moisture or nutrients from the tree. In other words, it is not a parasite. Its benefits are wide-ranging and play an important role in contributing to the biodiversity of woodland ecosystems and individual trees. The shelter and nesting opportunities provided by ivy are beneficial for many species of birds. It also provides habitats for insects. The berries produced provide a source of food for birds during the autumn and winter months when food is scarce. In addition, the nectar and pollen produced by the flowers are important for different species of insects.

In some cases, ivy can be found growing in large quantities on trees that are unhealthy and not growing well. Trees suffering from diseases or stress may have more open crowns which, in turn, allow the ivy present to grow vigorously with increasing light levels. In these situations the ivy can appear to be the cause of a tree's decline but, in effect, there are usually other underlying factors. The Department periodically carries out national forest inventories which collect a wide range of data that are used to assess, among other things, the total forest cover and the health of the forest estate. All plant species are recorded in forest plots taken as part of the inventory which includes ivy if it is present. The latest published forest inventory results from data collected in a period between 2004 and 2006 found that, in general, the health and vitality of forests in Ireland were considered to be good. The national forest inventory estimates that the total area of forest cover in Ireland is approximately 11% of the land area. As with all living things, there is a natural process and trees will either be felled for timber, succumb to disease or die of old age.

In the normal course of forest management ivy is not routinely removed and, in general, does not affect the productive capacity of healthy trees. In some cases, heavy growth of ivy on trees can make it more difficult to fell trees, but the impact is limited. Individual trees growing on roadsides can sometimes carry large amounts of ivy owing to a tree's weakened condition which can make a tree liable to fall over in high winds. Landowners in general should continue to monitor the condition of their roadside trees and remove unhealthy dangerous trees in the interests of health and safety.

In summary, it is not necessary to carry out a national tree survey to assess the impact of ivy on tree growth. That would prove to be an extremely costly exercise when it has been found that the current health and vitality of trees in Ireland’s forests are generally good. Even if Ireland were to instigate a strategy to remove or limit the growing of ivy, it would have consequences for biodiversity and reduce shelter for other species. Controlling ivy by removing a portion of the stem of the plant by manual cutting would have little impact as new plants would regenerate. Embarking on a national survey and control programme would not be effective and would not provide value for money. We should accept ivy as part of the community of plants found on trees.