Single mature trees in hedges enhance Devon’s landscapes and are very important for wildlife. Research reveals that trees substantially boost the numbers of insects, and so their predators like birds and bats, in landscapes. They also make it easier for many animals to move across the countryside. From a farming perspective, these hedge trees provide additional valuable shade and shelter for farm livestock. In our towns and cities they improve air quality by removing pollutants, especially health-damaging particles.
Ancient trees and those with veteran features like hollows and rot holes are especially important for wildlife. Species closely associated with hedgerow trees in Devon include the brown hairstreak butterfly, many species of bats and various rare lichens.
Numbers of trees are falling. This is partly because of diseases like Dutch elm disease and partly because few trees are being allowed to grow on to replace those that die from old age. Research shows that, to have a healthy hedgerow tree population, 40% of tree should be young (less than 20cm diameter at breast height), while in Devon only about 25% currently are. So we urgently need a new generation of hedgerow trees!
Ash dieback disease Hymenoscyphus fraxineus, often referred to as Chalara, is a major risk to Devon’s trees. Ash is our second commonest hedgerow tree, with an estimated 2 million mature or semi-mature specimens. The Devon Hedge Group, as a member of the Devon Local Nature Partnership, produced the Devon ash dieback management plan in February 2016. For a one page summary, see Key facts, impacts and actions. This document provides useful advice on tree and shrub species to replace ash.
Establishing trees in existing hedges is not always easy. The best way is often to leave promising specimens when a hedge is being layed or coppiced. Planting is often not successful because of intense competition for nutrients and light from existing plants. Aftercare of new hedgerow trees, whether planted or just earmarked for retention, is usually critical. Young trees usually need to be clearly marked for at least 5 years so that hedge cutters can see and avoid cutting them.
Hedgerow trees provides detailed guidance on the status of these trees in the county, which species to encourage, and how best to establish new ones. It also covers the management of existing trees to reduce impacts on crops, prevent damage to banks and reduce gap formation in the shrubs beneath.
Additional information on hedgerow trees is available in the Hedgelink leaflet Hedgerow trees: answers to 18 common questions.