Teagasc has provided a timely reminder of the key factors to consider when cutting hedges this autumn, explaining that a whole farm hedge management strategy is needed to ensure that hedges remain healthy and productive for wildlife and farming alike.

Hedges are among the most important habitats in agricultural landscapes because they are so widespread, according to Teagasc.

They play a significant role in sequestering and storing carbon, helping farms contribute to climate action. They regulate water, helping to reduce the risk of flooding and they filter water, keeping silt and nutrients out of rivers and streams.

Hedges are habitats for a wide range of wildlife. Over half of Ireland’s bird species - 55 in total - rely on hedges, with 35 species using them for nesting.

According to Teagasc countryside management specialist, Dr. Catherine Keena, all nine of Ireland's bat species use them as corridors of movement as well as for foraging and roosting.

Hedges support bees, moths, butterflies, and small mammals such as hedgehogs and shrews which live at their base, and they act as networks for nature, enabling wildlife to move safely through farmland and the wider countryside.

According to Teagasc, in summer, all hedges look good with their structure hidden by vegetation – both their leaves and ground vegetation growing alongside.

The time to assess the health of hedges is in the winter when they are dormant without their leaves. Light incremental trimming results in dense growth and healthy hedges, avoiding rough cuts.

Where hedges are regularly cut, there cannot be a dependence on the body of trimmed hedges to produce flowers and fruit.

So, a whole farm hedge management strategy is needed to ensure that hedges remain healthy and productive for wildlife and farming alike, according to Dr. Keena.

For management purposes, hedges fall into two categories – topped hedges and treeline hedges.

Any whitethorn in hedges will "want to grow into a single-stemmed tree with canopy full of flowers and haws", according to Teagasc. Topped/managed hedges are a man-made habitat. Treeline hedges are effectively narrow linear woodland.

The biodiversity value of treeline hedges is primarily in the canopy.

While they can be rejuvenated at the base by laying, these hedges are at high risk of being cut down incorrectly into ‘stumpy upside down toilet brush hedges’, as described by Teagasc, which have no base to support the hedge.

In addition, repeated cutting at the same height results in "death by a thousand cuts", according to Teagasc.

The advice is to value these treeline hedges and aim to have at least 50% of hedges on farms as this – often present on mearnings/external boundaries.

Treeline hedges generally do not need to be cut - they should never be topped, but overhanging branches can be cut if they are causing interference.

Scrub encroachment is addressed by grazing or cutting adjoining vegetation

The biodiversity value of topped hedges is said to be primarily in the dense base, providing nest sites for birds and cover for small mammals.

Topped hedges can still have some of the canopy biodiversity when occasional thorn trees are allowed grow and mature to flower and fruit freely.

Best practice management is to allow topped hedges grow as tall and as wide as possible - the bulkier the better, in a triangular profile to allow light to the base.

Apical dominance - where the whitethorn shrubs want to grow into trees - is managed by topping the growing point to prevent ‘escaping’ into a treeline hedge.

Light incremental trimming does not shatter stems and allow disease in. Little and often results in dense growth and healthy hedges.

The advice from Teagasc is also to retain a clump/bunch of thorn saplings from within every topped hedge this autumn.

For farmers and contractors, the message is clear: think before cutting. Leave one clump/bunch of thorn saplings in every topped hedge and retain or allow half of your hedges escape into treeline hedges.