Hedgerow and hedge trees
Hedge trees are traditionally part of the UK landscape and havens for wildlife. Yet, of an estimated 1.8 million hedge trees, nearly a third are over a century old and may disappear from the landscape at any time over the next 25 years. Without an immediate effort to establish new hedge trees, there will be profound changes to the UK landscape and its biodiversity. Since the late 18th century the abundance of hedge trees has dramatically declined. Periodic changes in farming techniques and agricultural needs, increased use of machinery, hedge removal, Dutch elm disease, neglect and lack of replacement have all taken their toll on the hedge tree population.
Hedgerow trees are important for several reasons. In the past they were highly valued for timber and with changing emphasis on renewable energy may once more come be useful for fuel. In livestock areas they are significant for shelter and shade, especially so as the climate changes and our summers become hotter, our winters wetter and we have more storms and gales. They are of great importance for wildlife and in some parts of the country they are notable as a source of fruit and other ingredients for food and drink. Trees in hedgerows often also screen eyesores and unsightly developments, and can protect privacy. Many of our most valued landscapes are dependent on hedgerow trees – without them, huge tracts of countryside would be bleak indeed.
In ancient hedges trees were selected and grown for a variety of specific uses. Oak, ash and elm were grown for timber amongst other purposes and appear to have been the commonest hedgerow trees. Willows and poplars were also frequent hedge trees and these species were often pollarded. Some minor trees species including field maple, aspen, holly and hornbeam also appear to have been specifically grown in hedges. In some places beech became a widespread hedge tree, and Exmoor’s landscape is famous for its 19th century beech hedges.
Along with timber species many fruit trees were also grown such as crab apple, wild cherry, hazel, elder and wild pear. These trees provided food in the autumn when other food supplies were beginning to run short.
Britain’s hedges contain an important collection of mature, over mature and ancient trees. In fact 30% of the hedge tree population is over 100 years old (CS2000). Part of the reason for this is the historical management they received. One of the main management techniques employed historically has been pollarding, which involves cutting the crown off a young tree at around 1.8-4.5m (6 to 15 ft) from the ground leaving behind a permanent trunk. Pollarding retains the tree in a state of greater vitality by interrupting the normal aging process and, since the crown is smaller, reducing the likelihood of storm damage. Pollarding trees has therefore allowed many to grow for several hundred years and some for much longer.
Hedge trees provide a whole range of habitats in one small area. Together with the hedgerow, they provide shelter, food, nesting sites, song posts and hiding places, as well as stepping stones between woodland habitats. Many farmland birds use hedgerows trees: buzzards build their nests in the canopy, while woodpeckers and tree sparrows breed in holes. Bats, including rarities like the barbastelle and Bechstein’s, roost in crevices and tree holes. The trunks of veteran trees can support rich lichen communities. Butterflies like hairstreaks may be seen foraging for honey dew from aphids and laying their eggs high up in oaks and elms.
Rotting wood in living and standing dead trees within hedges is especially important for providing habitats for a wide variety of dead-wood beetles such as the lesser stag-beetle (Dorcus parallelpipedus) and others, some of which are very rare.
There are several ways of establishing new hedge trees. You can select existing saplings (or promising coppice re-growth) already in the hedgerow; plant trees in existing gaps; create new gaps in which to plant by cutting notches in the hedgerow; plant trees beside the hedgerow rather than within it; or earmark saplings in a new hedgerow to become full-grown trees. Do think carefully about overhead services such as power lines which may cause future problems, and the risk of obstructing roads, tracks and rights of way.
When looking for existing saplings, select ones that are growing straight up all the way from the base. This should produce a good strong trunk if protected from cutting. Trees grown from stems that have been flailed, laid or coppiced may be so badly damaged that they are weak and unstable when mature. It’s often easiest to select and protect suitable saplings at the same time as laying or coppicing a hedgerow.
Many hedgerows will not contain suitable saplings, particularly dense single-species hawthorn and blackthorn hedges. Here it may be better to plant trees in gaps. Use existing gaps if possible because there will be less competition from existing plants. Otherwise, plant into a notch cut into the hedgerow.
Planting trees beside hedgerows may take up more space, but has the benefit of increasing the hedgerow width and its wildlife value. It may also be easier to cut the hedge in the future. There will be less root competition for nutrients and water, so the trees will probably grow faster. However, avoid planting trees on valuable habitats such as herb-rich grassland.
Planting trees when creating a new hedgerow is a very effective way of producing new hedge trees. Ideally, use species which are already growing in the locality, and invest in sturdy plants. Stakes or other supports are now only considered necessary for trees which are more than 1m tall and only for their first year. Once planted, use a marker stake and tree tag if necessary, to help prevent the trees being cut along with the rest of the hedgerow.
With urgent action needed to establish new hedge trees and prevent greater changes to the landscape and its biodiversity, The Tree Council, in partnership with Network Rail, is leading the Hedge Tree Campaign to increase awareness of why hedge trees matter and to halt their decline.
To champion the cause of hedge trees, the Tree Council is enlisting the support of its 7,500 volunteer Tree Wardens throughout the UK, its member organizations, local authorities and other supporters including farmers, landowners and contractors who are key to the success of the campaign. As many members of the general public as possible are also being encouraged to become involved.
The campaign will help to achieve the targets of local and national Biodiversity Action Plans for hedgerows. It will also help to maintain the overall number of hedgerow trees, estimated to be 1.8 million in Great Britain, through ensuring a balanced age structure. One way to ensure that there are hedge trees in the future is to mark newly-planted trees or existing saplings with easy-to-see tags. This will help whoever cuts the hedge to avoid the tagged young trees, allowing them to grow to maturity.
For more information visit The Tree Council’s website at www.treecouncil.org.uk
The Hedge Tree Handbook – The Tree Council
Hedge cutting: answers to 18 common questions – Natural England
Hedgerow trees: answers to 18 common questions leaflet (NE69) – Natural England
Hedgerow Survey Handbook – Defra (available from Natural England)
Hedges, E Pollard, M Hooper and N Moore
Hedges and Walls, T Williamson
The establishment of trees in hedgerows, S Hodge – Forestry Commission Research Information Note 195 1990