Teagasc Guide Available Online

Now that hedge cutting season is here again, it’s a chance to see what Teagasc are recommending for the management of hedges. Their key message is that there are two types of hedges based on structure, each with different biodiversity values and management requirements. Failure to distinguish between the two types can lead to confusion and inappropriate management. The Teagasc recommendation is that every farm should have some Escaped hedges and some Topped hedges. But first a reminder of what hedges bring to farms.

Hedgerows are Valuable Assets

We know that hedges are good for carbon storage and biodiversity but it’s not quite so easy to put a monetary value on the benefits hedges bring directly to farmers. That said hedges directly benefit farmers in several ways:

1) Water retention and regulation – trees help to improve the ability of soils to absorb and filter rain deep into the ground. In dry periods the areas nearest hedgerows can often continue to grow long after other areas have stopped.

2) Nutrient cycling – many farmers will remark that there’s often a rich swathe of grass near hedgerows which needs little fertilisation.

3) Shelter from wind and shade from sunshine. Livestock dislike extremes of wind chill or heat and hedges provide a simple way to enable stock to regulate their own temperatures, and thus maximise weight gain.

4) Agricultural Payments: under the new CAP scheme large areas of biodiversity such as hedges are recognised as essential features to ensure payments continue -in this sense, farmers are being encouraged to let hedges grow and expand.

5) In the absence of hedges to control livestock, farmers would be continuously spending on new and upgraded fencing. Therefore better to upgrade and enhance the existing hedges we have to keep livestock rather than large capital outlays on short-lived fencing.

6) Free Food and Medicine: farmers who keep more traditional livestock breeds will often remark that cattle and sheep will browse and self-medicate at the range of hedgerow plants available. As extreme droughts become more widespread farmers in many European nations are now increasing areas of tree and shrub cover to provide additional sources of fodder.

Escaped Hedges

Escaped hedges (Treeline / Linear woodland) which have never been topped, have high biodiversity value in the canopy, while thin at the base. Best practice management of Escaped hedges is to side trim only and never top.

Topped hedges

Photo above: Topped hedge side trimmed from a wide base to a triangular profile
Secondly, Topped hedges have high biodiversity value in the dense base for nesting birds and cover for small mammals and can also have some of the canopy biodiversity when occasional thorn saplings are allowed grow up and mature as flowering and fruiting thorn trees. Best practice management for Topped hedges is to side trim from a wide base to a triangular profile leaving as high as possible while still possible for the flail to to the peak to control apical dominance, but at least 1.5 m above ground level or top of bank (if present). Retain occasional thorn saplings to mature as standard thorn trees with a full canopy within every topped hedges.

Little and Often Is Best
Teagasc also emphasise that little and often trimming is better for hedges. Where best practice hedgerow management is followed on a farm, flowers and fruit are available on Escaped hedges and on the thorn trees retained within Topped hedges.
This is good for nature.

Problem Hedges

Some hedges may need more drastic remedial action to bring them back to a more useful state. Teagasc provide the example of the “Upside down toilet brush hedge” which is pictured below.

Photo above: ‘upside down toilet brush’ hedge being coppiced

Upside-down toilet brush hedges are topped hedges without a dense base. These weirdly shaped hedges have often come about as a result of Escaped hedges being cut down to a height of 1-1.5 m at some stage in the past. These are now ‘upside down toilet brush’ hedges and it is impossible to trim to a triangular profile. They are currently of low value for biodiversity and carbon. These are ideal candidates for coppicing under ACRES, in order to renew the base.

Photo above: Hedgerow coppicing

Where such hedges have a whitethorn stump every metre or so, there is great potential to improve their structure for biodiversity and carbon by coppicing. This involves cutting at ground level with a clean sloping cut so rain will run off.
Teagasc have a wide range of advisory information on their website and many guides and information leaflets are available at Teagasc office throughout the country.