Hedge

Formal, or modern garden hedges are grown in many varieties, including the following species:

• Berberis thunbergii - native to Japan and eastern Asia
• Buxus sempervirens (box) - native to western and southern Europe, northwest Africa, and southwest Asia, from southern England south to northern Morocco, and east through the northern Mediterranean region to Turkey.
• Carpinus betulus (European hornbeam) - native to Western Asia and central, eastern, and southern Europe, including southern England.
• Crataegus monogyna (hawthorn) - native to Europe, northwestern Africa, and West Asia
• Fagus sylvatica (European green beech) - native from northern Europe, in Sweden, Denmark, Norway, Germany, Poland, Switzerland, Bulgaria, eastern parts of Russia, Romania, through central Europe to France, southern England, northern Portugal, central Spain, and east to northwest Turkey where it intergrades with the oriental beech (Fagus orientalis)
• Fagus sylvatica 'Purpurea' (European purple beech) - a variant of the above
• Ilex aquifolium (European holly) - native to western and southern Europe, northwest Africa, and southwest Asia
• Ligustrum ovalifolium (privet) - native to Japan and Korea
• Ligustrum × ibolium (north privet) - native to Japan and Korea
• Photinia × fraseri (red robin) - a hybrid between Photinia glabra and Photinia serratifolia, native to Japan and to China, Taiwan, Japan, the Philippines, Indonesia, and India, respectively
• Prunus laurocerasus (common laurel) - native to regions bordering the Black Sea in southwestern Asia and southeastern Europe, from Albania and Bulgaria east through Turkey to the Caucasus Mountains and northern Iran
• Prunus lusitanica (Portuguese laurel) - native to southwestern France, Spain, Portugal, Morocco, and Macaronesia (the Azores, Canary Islands and Madeira)
• Quercus ilex (holm oak) -native to the Mediterranean region
• Taxus baccata (yew) - native to Western Europe, Central Europe and Southern Europe (including Great Britain and Ireland), Northwest Africa, northern Iran, and Southwest Asia
• Thuja occidentalis (yellow ribbon; northern white cedar) - native to eastern Canada and much of the north-central and northeastern United States
• Thuja plicata (western red cedar) - native to the Pacific Northwest of North America

Hedgerows between fields in North Dakota

Oak and beech hedges are common in Great Britain

Hedgerow trees are trees that grow in hedgerows but have been allowed to reach their full height and width. There are thought to be around 1.8 million hedgerow trees in Britain (counting only those whose canopies do not touch others) with perhaps 98% of these being in England and Wales.[6] Hedgerow trees are both an important part of the English landscape and valuable habitats for wildlife.[6] Many hedgerow trees are veteran trees and therefore of great wildlife interest.

The most common species are English oak (Quercus robur) and ash (Fraxinus excelsior), though in the past field elm (Ulmus minor 'Atinia') would also have been common. Around 20 million elm trees, most of them hedgerow trees, were felled or died through Dutch elm disease in the late 1960s. Many other species are used, notably including common beech (Fagus sylvatica) and various nut and fruit trees.[6]

The age structure of British hedgerow trees is old because the number of new trees is not sufficient to replace the number of trees that are lost through age or disease.[6]

New trees can be established by planting but it is generally more successful to leave standard trees behind when laying hedges. Trees should be left at no closer than 10 metres (33 ft) apart and the distances should vary so as to create a more natural landscape.[6] The distance allows the young trees to develop full crowns without competing or producing too much shade.[6]

It is suggested that hedgerow trees cause gaps in hedges but it has been found that cutting some lower branches off lets sufficient light through to the hedge below to allow it to grow.[6]

Beech planted on a march dyke (boundary hedge) of the 18th century.

Hedges that have existed for hundreds of years are colonised by additional species. This may be useful as a means of determining the age of the hedge. Hooper's rule (named for Dr. Max Hooper) is based on ecological data obtained from hedges of known age, and suggests that the age of a hedge can be roughly estimated by counting the number of woody species counted in a thirty-yard distance and multiplying by 110 years.[12]

Max Hooper published his original formula in the book Hedges in 1974. This method is only a rule of thumb, and can be off by a couple of centuries; it should always be backed up by documentary evidence, if possible, and take into account other factors. Caveats include the fact that planted hedgerows, hedgerows with elm, and hedgerows in the north of England tend not to follow the rule as closely. The formula also does not work on hedges more than a thousand years old.

Hooper's scheme is important not least for its potential use in determining what an important hedgerow is, given their protection in The Hedgerows Regulations (1997; No. 1160) of the Department of the Environment, based on age and other factors.[13]

Hedgerow removal is part of the transition of arable land from low-intensity to high-intensity farming. The removal of hedgerows gives larger fields making the sowing and harvesting of crops easier, faster and cheaper, and giving a larger area to grow the crops, increasing yield and profits.

Hedgerows serve as important wildlife corridors, especially in the United Kingdom where they link the country's fractured ancient woodland. They also serve as a habitat for birds and other animals. As the land within a few metres of hedges is difficult to plough, sow, or spray with herbicides, the land around hedges also typically includes high plant biodiversity. Hedges also serve to stabilise the soil and on slopes help prevent soil creep and leaching of minerals and plant nutrients. Removal thus weakens the soil and leads to erosion.

In the United Kingdom hedgerow removal has been occurring since World War I as technology made intensive farming possible, and the increasing population demanded more food from the land. The trend has slowed down somewhat since the 1980s when cheap food imports reduced the demand on British farmland, and as the European Union Common Agricultural Policy made environmental projects financially viable. Under reforms to national and EU agricultural policies the environmental impact of farming features more highly and in many places hedgerow conservation and replanting is taking place.

In England and Wales agricultural hedgerow removal is controlled by the Hedgerows Regulations 1997, administered by the local planning authority.

Trimmed hedges at Mission San Juan Capistrano in California

An alternative to hedge laying is trimming using a tractor-mounted flail cutter or circular saw, or a hedge trimmer.[15] The height of the cutting can be increased a little every year. Trimming a hedge helps to promote bushy growth. If a flail cutter is used, then the flail must be kept sharp to ensure that the cutting is effective on the hedge. The disadvantage of this is that the hedge species takes a number of years before it will flower again and subsequently bear fruit for wildlife and people.[16] If the hedge is trimmed repeatedly at the same height, a 'hard knuckle' will start to form at that height – similar to the shape of a pollarded tree. Additionally, hedge trimming causes habitat destruction to species like the small eggar moth which spend nearly their entire life cycle in blackthorn and hawthorn hedgerow. This has led to a decline in the moth's population. It is now nationally scarce in Britain.[17]

A 'hedgerow management' scale has been devised by an organisation called Hedgelink UK[18] ranging from 1 to 10. '1' describes the action to take for a heavily over trimmed hedge, '5' is a healthy dense hedgerow more than 2 metres in height, and '10' is a hedge that has not been managed at all and has become a line of trees.

The RSPB suggest that hedges in Britain not be cut between March and August. This is to protect nesting birds, which are protected by law.[19]

The techniques of coppicing and hard pollarding can be used to rejuvenate a hedge where hedge-laying is not appropriate.[20]

The term instant hedge has become known since early this century for hedging plants that are planted collectively in such a way as to form a mature hedge from the moment they are planted together, with a height of at least 1.2 metres. They are usually created from hedging elements or individual plants which means very few are actually hedges from the start, as the plants need time to grow and entwine to form a real hedge.

An example of an instant hedge can be seen at the Elveden Hall Estate in East Anglia,[21] where fields of hedges can be seen growing in cultivated rows, since 1998. The development of this type of mature hedge has led to such products being specified by landscape architects, garden designers, property developers, insurance companies, sports clubs, schools and local councils, as well as many private home owners. Demand has also increased from planning authorities in specifying to developers that mature hedges are planted rather than just whips (a slender, unbranched shoot or plant).

Instant hedge growing in fields at Elveden Estate

A 'real' instant hedge could be defined as having a managed root growth system allowing the hedge to be sold with a continuous rootstrips (rather than individual plants) which then enables year-round planting. During its circa 8-year production time, all stock should be irrigated, clipped and treated with controlled-release nutrients to optimise health.

A quickset hedge is a type of hedge created by planting live whitethorn (common hawthorn) cuttings directly into the earth (hazel does not sprout from cuttings).[22] Once planted, these cuttings root and form new plants, creating a dense barrier. The technique is ancient, and the term quickset hedge is first recorded in 1484.[23] The word quick in the name refers to the fact that the cuttings are living (as in "the quick and the dead"), and not to the speed at which the hedge grows, although it will establish quite rapidly. An alternative meaning of quickset hedging is any hedge formed of living plants or of living plants combined with a fence. The technique of quicksetting can also be used for many other shrubs and trees.

A traditional stone-faced Devon hedge at Beaford, with stones placed on edge

A Devon hedge is an earth bank topped with shrubs. The bank may be faced with turf or stone. When stone-faced, the stones are generally placed on edge, often laid flat around gateways.

A quarter of Devon's hedges are thought to be over 800 years old.[24] There are approximately 33,000 miles (53,000 km) of Devon hedge,[24] which is more than any other county. Traditional farming throughout the county has meant that fewer Devon hedges have been removed than elsewhere.

Devon hedges are particularly important for wildlife habitat. Around 20% of the UK's species-rich hedges occur within Devon.[25] Over 600 species of flowering plants, 1500 species of insects, 65 species of birds and 20 species of mammals have been recorded living or feeding in Devon hedges.[25]

Hedge laying in Devon is usually referred to as steeping and involves cutting and laying steepers (the stems) along the top of the bank and securing them with crooks (forked sticks).

A Cornish hedge is an earth bank with stones.[26] It normally consists of large stone blocks constructed either side of a narrow earth bank, and held in place with interlocking stones. The neat rows of square stones at the top are called "edgers". The top of the hedge is planted with grass turf.[27]

Sometimes hedging plants or trees are planted on the hedge to increase its windbreaking height. A rich flora develops over the lifespan of a Cornish hedge. The Cornish hedge contributes to the distinctive field-pattern of the Cornish landscape and its semi-natural wildlife habitat. There are about 30,000 miles (48,000 km) of hedges in Cornwall today.[28]

Hedges suffer from the effects of tree roots, burrowing rabbits, rain, wind, farm animals and people. How often repairs are needed depends on how well the hedge was built, its stone, and what has happened to it since it was last repaired. Typically a hedge needs a cycle of repair every 150 years or so, or less often if it is fenced. Building new hedges, and repairing existing hedges, is a skilled craft, and there are professional hedgers in Cornwall. The Cornish Hedge Research and Education Group (CHREG) supports the development of traditional skills and works with Cornwall Council, FWAG (Farming and Wildlife Advisory Group), Stone Academy Bodmin, Cornwall AONB, Country Trust and professional hedgers to ensure the future of Cornish Hedges in the landscape.