Recently one of our park users wrote to ask why the APF volunteers were not keeping the trees clear of ivy. He feared that it did damage to the trees and that the weight of the extra growth could cause trees to fall in high winds. This is a question that often arises, so we asked the experts.
Dr. Alan Feest (Chartered Ecologist) wrote some time ago in the Bath Chronicle:
- Ivy is the last native pant to flower and is an essential source of nectar for insects wishing to stock up on energy before hibernating overwinter. Often Red Admirals and Small Tortoiseshells can be seen on ivy into October or even in November along with numbers of Bumble Bees and Hover Flies.
- Ivy is the last berry to ripen in the winter and is essential food for berry feeding birds in late winter. Often Wood Pigeons can be seen desperately flapping about to try to get the last fruit or Blackcaps dashing in to grab a berry.
- In our native woodland there is a dearth of cover for overwintering animals and ivy is essential for many mammals (especially bats) and insects because it provides shelter from wind and rain.
- Ivy is often mistakenly thought to be parasitic on trees but it only uses trees as a support and when a tree is healthy there is too much shade for the ivy to grow up the tree and it is confined to the woodland floor. Only as a tree senesces and the crown thins does ivy travel up the tree. This is obviously the case or ivy would not be able to climb up walls. To see the little roots on the ivy look under a stem and see the clusters of short adhesive roots holding the stems on to the tree, wall etc.
- The combination of the above four properties means that, far from being a nuisance, ivy is probably the most valuable plant in a wood for wildlife.
Our local RSPB man – John Yates – recommends ivy-covered trees for siting robin nest boxes, as they prefer their nest to be hidden in foliage.
We also asked the BANES Tree Officer about this. Their opinion was that ivy is a very useful habitat, that it isn’t a parasite and doesn’t generally cause harm to trees.
The council will often sever or remove ivy from trees in high risk locations (where if a tree failed there is a high risk it could cause damage or injury), so that the stems can be checked for defects, etc. Otherwise it is left.