FLAILING FAILING

Photo caption: A flailed hedge in winter illustrating branch damage and a poor finish.

In many areas in recent times flails have overtaken reciprocating cutters and shears in managing hedgerows. Flails, usually tractor mounted, are quick and easy, and therefore less labour-intensive, cheaper and require relatively little skill to use. We hear much about the grubbing out of our hedgerows, an act of great countryside vandalism in itself, but little about the damage that overzealous or careless flailing is doing to the hedges that remain, or even recently-planted ones. 

In brief, the problem is this: flails, especially when used over-zealously, macerate the hedges’ branches and twigs (see photo), spewing out a chewed-up mess of twiggy fragments that is left behind to carpet the ground. 

Harsh flailing also slashes the thicker stems as can be seen in the foreground of the photo, forming ragged wounds. This opens much greater opportunities for the entry of pathogenic bacteria and fungi than a clean cut. Moreover, the carpet of mashed up wood and twigs disgorged by the flail (and hardly ever swept up) suppresses the hedge-associated ground flora and thus has an adverse impact on biodiversity and favourable conservation status that is contrary to planning guidance and best practice. And it looks horrible.

What many do not realise is that the twiggy ends of the hedgerow shrubs are home to the winter pupae and sometimes ova or even larvae of several invertebrates which stand no chance of survival a flail. Conversely, reciprocating cutters neatly clip off the protruding twigs which, when falling back into the hedge or onto the ground before gathering up, allows at least some invertebrates that were on them to survive.

One insect that is thought to have severely declined in step with the increased use of hedge flails is the hawthorn sawfly Trichiosoma tibiale Stephens, 1835 (Hymenoptera, Cimbicidae). This is a large and hairy sawfly as big as a bee: the adults are on the wing from April to June, though you will be lucky to see them these days.

Superb Bio-Image of the hawthorn sawfly by Malcolm Storey licensed under Creative Commons 2.0 UK. Thank-you. 

There are not many more than twenty British records in the NBN Atlas for this sawfly, some unconfirmed due to difficulties in identification (the males are almost impossible to separate from T. lucorum), and several of which date from decades ago. Its larvae feed on hawthorn but they tend to pupate on the distal part of the twigs. They are in a tough cocoon but these are no match for the hedge-cutting flails.

Yes, I know there are times when very neglected hedges need major surgery and that re-laying is usually impractical for financial reasons and lack of skilled people to do it. I also realise that flails in the hands of competent operators can leave a tidy finish, but I would like to make a plea for the return of reciprocating cutters as the norm: small, large, and tractor-mounted ones are readily available. They may take a little more time and skill and so cost more, but they will help our hedgerow wildlife. What price do you put on that? 

Recent research, for example that gathered in The Ecology of Hedgerows and Field Margins edited by J. W. Dover (Routledge, 2019) shows that hedgerow management has a significant impact on the value of hedges for wildlife in terms of ecological connectivity (“wildlife corridors”), faunal food resources (especially flowers, fruit, and foliage), and in changing ecological factors such as predation and parasitism. On balance and perhaps unsurprisingly, the research shows that various hedgerow management regimens affect different wild species in different ways. Whilst heterogeneity of management is considered the best option over a large site, the best “standard” regime is to cut in late winter rather than autumn and to promote taller, wider hedges using an “incremental cutting intensity” that allows smaller hedges to grow larger by, say, 10cm in breadth and height each year, and not cutting all the hawthorn in a way that removes all previous year’s growth where flowers and fruit are formed for the following year.

Betts Ecology’s hedgerow management policy can be found at: https://www.bettsecology.co.uk/policies

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