Ivy (Hedera helix) is native to Europe and Asia and forms an important part of our British ecosystems. Ivy may be viewed as an invasive plant in the United States, but it does not originate in the US and out-competes American native floral species. Here in the UK, however, it forms complex communities with other species of our native flora and fauna, and even if it climbs trees or covers the floor of recent woodland it is acting entirely naturally. Importantly ivy does not damage healthy trees. If a tree is dead then a great weight of ivy could contribute to the tree falling in high winds, but this is simply part of the natural process of decay and nutrient cycling.
Ivy has two forms; juvenile and adult. Juvenile ivy has distinctive lobed “ivy shaped” leaves and is found creeping along the ground, climbing up walls and on the base of trees. Commonly it is the adult flowering form of the plant that climbs up into trees. When ivy is severed at the base of trees this flowering form is killed off thereby removing an important food source for many animals. Over seventy species of invertebrates are known to feed on ivy, including the holly blue butterfly which depends on ivy as a food plant for its summer brood. Ivy flowers are produced from summer to autumn and provide a significant late source of nectar for bumblebees and other insects. Following pollination ivy produces black berries that ripen over winter. At least 17 species of bird including blackcap (Sylvia atricapilla) and redwing (Turdus iliacus) have been seen feeding on the berries, which can be a vital food source at the end of harsh winters. Ivy’s evergreen foliage provides shelter for many animals, including birds in and out of the nesting season. In particular the wren (Troglodytes troglodytes) benefits from the protection that ivy gives in winter; the large numbers of breeding wren at Nunhead Cemetery are likely to be down to the high abundance of ivy. Furthermore, a thick covering of ivy on a mature tree increases its value as a roost for bats, one of the UK’s most highly protected species.
Although the article in the December issue briefly mentions the benefits of ivy the author appears to advocate removal of ivy from shrubs, trees and buildings from his view of what he judges to be aesthetically pleasing, which is highly subjective. Unfortunately this view is not unusual. The culture of arboricultural and horticultural aesthetics over the past two centuries has influenced attitudes to ivy, by denigrating it for its wildness rather then recognizing it as part of our ecology.
The December article also featured pictures of two trees along Cox’s Walk. Cox’s Walk is managed by the London Wildlife Trust with the conservation of wildlife habitat as its utmost priority, and whilst we maintain our trees to be safe, our policy is to encourage ivy where we possibly can. We are concerned by the practice of ivy being severed at the base of trees and hope that knowledge of the importance of ivy to wildlife may dissuade people from carrying this out in future.
Ashley White, Manager of Sydenham Hill Wood and Cox’s Walk & Conservation Projects Officer, Southwark www.wildlondon.org.uk