Hedges are often a central feature of highly valued landscapes that provide a link to centuries of farming activity.
Variation in hedgerow types and management styles characterise different regions of the UK.
All hedges need management to maximise their value for wildlife, and to boost the production of flowers and berries. The best hedges are managed rotationally for a diverse range of ages and structures. They include mature hedgerow trees which are of particular value for bats and insects, as well as standing dead wood. They are often complemented by buffer strips of ungrazed or uncut grassland, which provides additional habitat for wildlife. Where they occur, hedge banks of earth and stone-faced can be of great importance for reptiles for hibernation and basking.
Hedges provide key habitat and resources for wildlife, including food, navigation and breeding sites. They also provide a safe way for wildlife to move through the landscape. Hedgerows support populations of pest predators and provide a home for pollinators adjacent to crops.
Different hedge sizes, types and features are of value to different species, so the best hedges for wildlife have a varied character along their length and will attract a wider range of wildlife. Short hedges with wide grass buffer strips are preferred by grey partridges, linnets and yellowhammers. Lapwings and corn buntings, however, require open fields with short hedges or hedgeless bank. Tall and wide hedges suit turtle doves, bullfinches and song thrushes. A good shrub layer and growth at the base is of great benefit to many species including hedgehogs, amphibians and reptiles.
Rotational hedgerow trimming will help to create this diverse structure, as well as boosting flower and berry production for wildlife. Flower buds on many hedge plants form on second-year growth, so annual cutting can prevent them forming. Rotational trimming therefore has huge benefits for a range of insects including crop pollinators, as spring blossom is a vital resource in the landscape. This can also reduce the time and money spent on annual cutting.
Suitably managed hedges will provide diverse nesting habitat for birds and mammals as well as providing food and shelter throughout the year. Hedgerow trees are of particular importance for wildlife, as old trees will provide space for hole-nesting barn owls and tree sparrows, and bats and the insects that they feed on.
Cutting strategies can be tailored to suit the hedgerow species present on the farm, adjacent habitats and the local landscape character. Tall hedges with plenty of hedgerow trees are ideal for connecting woodlands, helping the movement of small mammals and amphibians through the landscape, and for foraging and navigation by bats. Hedges with wide grass or wildflower margins are ideal for connecting unimproved grasslands. Short hedges without trees are better in areas where ground-nesting birds prone to predation breed.
Hedges should not be trimmed during the peak nesting season for birds, between March and September. If you can delay trimming until January and February, the berry crop will provide valuable food for wildlife. If this is not possible, a 3-year rotation is required to provide a bumper crop of berries in one year of the rotation. Cutting is usually undertaken with a flail, but a circular saw is a less damaging alternative which creates a cleaner cut and encourages better re-growth.
Rotational trimming of hedges ensures an annual resource of flowers and berries. In a 2-year rotation, cut half of the hedge each winter (a 2-year rotation with a cut in autumn provides little benefit compared to annual trimming). On a 3-year rotation, cut a third annually. Avoid cutting the entire hedge in the same year to provide continuity of habitat and resources. Hedges can be cut rotationally across the whole hedge (both sides and top) or can involve leaving one side uncut or leaving the top uncut to encourage upward growth. A sheltered, south-facing area of hedge left uncut each year will provide an important refuge for insects.
Some hedges can be allowed to grow taller and wider by not cutting back to the previous cut line annually (reduced cutting intensity), allowing a small expansion each time. This can create a greater variety of hedge sizes around the farm. Reduced cutting intensity can be useful for an early autumn cut on hedges in wet areas where a late winter cut may not be possible.
Grass buffer strips
Buffer strips of at least 2m will protect the hedge from inputs and provide habitat for wildlife. Where a hedge includes several mature trees, extend the buffer strip to protect the roots from damage during cultivation.
Grazing livestock can reduce the wildlife value of hedgerows, and even threaten its long-term survival. If fencing is required to protect the hedge, erect it 2 to 3m away from the centre of the hedge. Rather than tightly following the curves of the hedge, consider fencing longer straight runs, so that some rough grass can develop where the fence is further from the hedge.
Restoring gappy hedges
Planting up any gaps is best undertaken using locally-sourced native hedge plants in early winter, when the ground is warm and moisture is available.
If existing hedgerows lack a thick base, combine planting with coppicing to give the new plants minimum competition. Before planting, the ground should be free of vegetation (use a suitable herbicide if necessary). Alternatively, you can plant through black polythene to suppress weeds and reduce moisture loss.
It may be necessary to use plastic tubes, spirals or quills to protect young plants from grazing rabbits or deer (removing the cuttings if possible).
Restoring overgrown and leggy hedges
If a hedgerow has lost its bushy base and resembles a line of trees, it can be restored in the winter through laying or coppicing.
Laying (cutting stems part way through and interweaving them along the hedge line) has a less drastic effect on wildlife than coppicing, but needs skilled labour. Recommence trimming in the following winter, and in the direction in which the stems have been laid.
Coppicing (cutting the stems at ground level) is best where the hedge is too overgrown to be laid because the stems are too thick. The stumps may need protection from browsing by rabbits and deer.
Both forms of management will reduce breeding opportunities for birds in the years immediately after management, so should be carried out over many years rather than managing large sections in one year. If there is any potential for bat roosts being present, these must be taken into account before work is undertaken and if necessary specialist advice sought.
If possible, pile removed wood somewhere that does not interfere with farming operations to provide valuable dead wood habitat and refuge areas for wildlife.
Hedgerow tree management
Mature and dying trees are home to a wide variety of insects and other animals that may not be found elsewhere on the farm. Because of their importance, such trees require protection and a long-term plan to replace them. Tag native saplings in the hedge that have not been cut in previous operations and leave these during future trimming. Choose species that are present as hedgerow trees in your area, such as oak, ash, cherry or willow. Alternatively, native saplings from local sources could be planted.
Retain old, dying and dead trees where these are not a hazard, as they support important insect communities, bat roosts and may be used by hole-nesting birds. Rotten tree stumps and voids around root systems are features which may be used for hibernation by reptiles and amphibians.
Here are some useful case studies and articles about how farmers are putting Farm Wildlife into practice on their farms
Author: Craig Dunton, Grey long-eared bat Project Officer, Bat Conservation Trust Species: Grey Long-eared bat: © Craig Dunton/www.bats.org.uk Why is farmland important for this species? With as few as 1000 individuals In the UK, the grey long-eared bat is one of our rarest mammals. Their distribution is restricted to the southern coast (Devon, Dorset, […]Read More
Hedgehogs have been associated with farmland for centuries. Hedgehogs are insectivores, foraging in fields and on grassland for worms, and along field margins and at the base of hedgerows for beetles, snails and other invertebrates. They are considered a generalist species, but as the dominant habitat in the UK, farmland is particularly important for hedgehogs.Read More
Author: Jo Terry Farm: Upper Hollowfields Farm, Worcestershire Aims: Upper Hollowfields is a mixed farm with arable crops and cattle/sheep grazing the grassland areas. The hedgerow pattern contributes to the historic character of the site. Hedge management is considered carefully in each field, where possible complimenting other environmental work on the farm, for example higher, thicker […]Read More