HAVE you thought of planting a new native hedge on your farm? It will be good for nature, air quality, shelter, will add to the landscape, and be a legacy for future generations.

Hedgerows give the Irish landscape its distinctive character and field pattern. Birds, bats and bees uses them as roadways or corridors of movement as well as nesting, feeding and shelter.

Increasing the variety of hedgerow types in terms of height, width, shape and species mix promotes diversity in flora and fauna. While hedges are the most common habitat on most Irish farms, management of some could be better. High quality hedgerows provide multiple benefits.

Strategically located hedges act as barriers to overland flow of water, preventing sediment and nutrients entering watercourses, improving water quality. This regulation of water flow can reduce flooding. With an estimated 689,000km of hedgerows in Ireland their future role in carbon sequestration will also be vitally important.

There are approximately 100 plant species associated with native Irish hedges. These include trees, shrubs, climbers and herbs. When it comes to biodiversity, the most important single component in the value of a hedgerow is the permanent inhabitants in the hedge, the woody species, the trees and shrubs.

Let’s start at the top. Three large native Irish trees are frequently found in hedges. Oak, ash and willow provide a habitat for numerous invertebrates as well as birds such as the two Irish owls, barn owl and long-earred owl.

Biodiversity

In very wet ground alder, willow or birch may be used. Whether you like it or not, ivy is a plant of immense biodiversity value which provides nest sites for bats and birds. Its flowers in September/October are the only source of pollen and nectar to bees and hoverflies at that time of year. Ivy’s late ripening berries, still available in January and February, may be the only source of food for birds when all else is gone.

Moving down to the body of the hedge, the most predominant and valuable shrub in native Irish hedges is whitethorn (hawthorn) with white flowers amid green leaves in late May and producing red haws in autumn. Thorn hedges may also include blackthorn which has white flowers on black leafless branches in late March followed by dark coloured sloes in autumn. Deep within these thorny hedges is a safe nesting area for songbirds such as blackbirds and thrushes.

Of the 110 bird species regularly recorded during the breeding season in Ireland 55 use hedgerows. Of these, 35 species nest in the hedgerows which provide cover from overhead and ground predators. The presence of holly, honeysuckle or woodbine and flowering climbers such as bramble or blackberry are a valuable food source for bees and fruits for birds and mammals.

The dense base of a hedge is home to small birds such as robin and mammals including hedgehogs and shrew. In hard weather this may be the only unfrozen foraging ground available. Woodland plants such as primrose, cowslips, ferns and foxglove adorn the hedge base and are a great source of food for pollinators. Currently a third of bee species are threatened with extinction due to lack of food, flowers and safe nesting sites.

Horse chestnut, sycamore and beech which are not native to Ireland are not as valuable from a biodiversity perspective. Indeed sycamore should not be used on the basis of the potential for its seeds to cause poisoning in equines. While beauty is in the eye of the beholder, manicured beech hedges often present on stud farms and training establishments, are not good for biodiversity.

Management of hedges

There are in essence two types of hedge: the traditional topped hedge with a dense base, trimmed regularly, with the growing point cut; and the un-topped or escaped hedge/line of trees/strip of woodland.

With the topped hedge culture change in preference for tightly manicured hedgerows ‘short back and sides’ is necessary to protect biodiversity. Attitudes considering less manicured hedges as ‘lazy management’ need to be re-educated. The quest for neatness should not override ecological considerations. Best practice management for topped hedges are to side trim from a wide base to a triangular profile, leaving the peak as high as possible as long as the hedge cuter can reach to cut the growing point; and retaining occasional individual whitethorn trees at irregular intervals. The un-topped hedge can be side trimmed but should never be topped unless rejuvenating at ground level.

The season for hedge-cutting closes on March 1st, 2021 will reopen on September 1st. Although permitted to cut hedges in autumn, please remember that this is an important time for wildlife as they build their stores for the winter. Hold off cutting hedges heaving with fruits, nuts, and berries if possible, until later in the hedge cutting season.

Planting new hedges

Firstly decide if you want a traditional, managed topped hedge; or an un-topped line of trees and shrubs. Both will be based on whitethorn and can include other species that tolerate regular trimming such as blackthorn, holly, spindle, guelder rose, hazel, dog rose and woodbine.

Trees such as mountain ash, alder, birch, cherry and whitebeam should only be included in the un-topped hedge/line of trees. If included in the topped hedge they must be retained as individual trees and not topped, but preference must be given to retain whitethorn or other flowering species as trees first.

Choose native species and preferable plants of native provenance which have been grown in Ireland from seed collected from Irish trees.

Further information and video clips from Teagasc Hedgerow Week can be found on teagasc.ie/environment/biodiversity--countryside/farmland-habitats/hedgerows/.