Managed hedgerows can host plenty of biodiversity

Hedgerows and how to manage them is a topic of conversation becoming more popular.

In a recent episode of Teagasc’s The Dairy Edge Podcast, Catherine Keena busted some myths on hedgerows and how to improve biodiversity on farms.

Catherine, who is a countryside management specialist with Teagasc, explained that the majority of hedgerows in this country are “a line of whitethorn quicks which would have been planted approximately 200 years ago”, and she noted that our towns’ land boundaries would be older than that.

Catherine explained: “Because they have been maintained they have remained as a hedgerow. The whitethorn quicks that you plant want to grow up to be a tree with a full canopy and a single bowl.

“If it’s left un-managed the hedging plant will grow up into a tree; a line of whitethorn trees, which themselves are beautiful.

“They have the height. They have the flowers, but they don’t have the dense space then, so a hedgerow is actually an artificial habitat. It’s a managed habitat. That doesn’t make it any less. It’s very important to understand.”

Managing hedgerows for biodiversity

Managed hedgerows are cut at the growing point to ensure a thick hedge, but there are techniques that can be implemented to improve the biodiversity.

“For those type of hedgerows that we’re maintaining with the dense space and cutting the growing point we need to leave it at least 1.5m [in height above ground level] or birds will not nest in it; and we also need to leave occasional stems to grow up into an individual whitethorn tree which will have lots and lots of flowers and fruit on it.

Our routinely managed hedgerows can be very good for biodiversity if they’re managed for birds and bees.

Side-trimming hedgerows

Catherine outlined that the second type of hedgerow is where it has already escaped into a tree. These hedges should not be topped, but should be side trimmed.

“I think it’s important to think why we are cutting. The main reason is to stop outgrowth into the field and that’s perfectly fine. Side trimming is always perfectly acceptable.

I think it’s when we go too hard on the height that’s where it’s not good. We will have no birds in it if it’s less than 1.5m above ground level, which could be the top of the bank.

“You could have a very small fringe of hedging on the top of a bank which no bird will nest in and if there are no flowering stems allowed to mature we will have no flowers for the bees.”

Change needed

Traditionally in Ireland, tidy hedgerows cut to a low height are preferred by many farmers.

“We need a huge sea change here in accepting that people might like neat and tidy, but if you have a very short back and sides hedgerow there are no birds or bees in it and it’s easy to change that, but we need the general public and everybody to understand.

“Not so long ago the attitude would be that if the hedges aren’t down at that level they mustn’t be a good farmer so we really need a change in everybody’s attitude or understanding of what we want from our hedgerows.”

Retain

Catherine noted that it’s better to rejuvenate existing habitats or hedgerows before creating new ones.

“If there are hedgerows that you want to rejuvenate by laying or coppicing then you put your effort into those old hedgerows that can be renewed before we come to the last step which is creating new habitats.”

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