Case Study: Managing hedges on an extended rotation – Using an excavator mounted finger bar and tree shear

Author: Fraser Hugill: Throstle Nest Farm, Sproxton, North Yorkshire

The Management Challenge

In recent years I have taken over the management of the family farm. The farm business consists of 350 acres, split over two different holdings, both with fantastic hedgerow networks that support lots of wildlife but with very different management needs. I wanted to find a way to manage the hedges myself that would be cost-effective and benefit wildlife.

The solution came in the form of digger-mounted finger bar cutter and tree shear. The results have been really good for hedges, wildlife and soil – and have given me the perfect excuse to keep the farm’s best big boy’s toy - the digger.

The two holdings that make up my farm business are Throstle Nest, on the southern edge of the North York Moors, and White House, on the northern edge of the moors. The farm is roughly 50% arable (Winter Wheat, Winter Barley, Spring Beans, Oats) and the remainder a mix of permanent pasture and grass/herbal leys supporting a herd of 50 pedigree Beef Shorthorn suckler cows.

Throstle Nest has a really intact hedgerow network, very similar to 1840s maps, with species-diverse hedges. Prior to our arrival these appeared to have been trimmed annually and were grazed by sheep, but were generally in a good condition. Throstle Nest also has heavy clay soils which are waterlogged throughout winter. This means that using a conventional tractor-mounted flail cutter was only viable in the Autumn as the wheels cause too much damage to the ground in spring.

White House has had very little hedgerow management - Dad pretty much ignored them, which created a good habitat, but hedges were starting to grow out and lacked structural diversity. Although Dad’s management had benefits for wildlife, this management could not go on indefinitely!

Both farms are in Countryside Stewardship with both agreements up for renewal. The current agreements include hedgerow revenue and capital options to gap up and coppice hedges, and these options will be included in the new agreements.

Managing Hedges with Excavator Mounted Equipment

Moving to Throstle Nest in 2012 involved a lot of infrastructure work so we purchased a 5-tonne excavator. The plan was originally to sell it once work was complete, however this prospect was akin to taking away a children’s favourite toy!  So, somehow this had to be justified. But how? By buying more toys to attach to it of course!

The first piece of kit was a Slanetrac 1.8 metre finger bar hedge trimmer which runs off the excavator’s third service. It works as a combine cutter bar using the same blades as our combine. Unlike a tractor-mounted flail, cutting is done in one single pass, so no going backwards and forwards which risks increased damage to the ground.

Cutting involves staying in one position to cut 4-5 metres off the hedge side and then from the top. Then moving another 4-5 metres forward to the next section. This gives excellent control, particularly when cutting larger sections of hedge.

 

Bar hedge trimmer cuts through 3 - 4 yr old hedge wood
Bar hedge trimmer cuts through 3 - 4 yr old hedge wood
Cutting several feet of mature hedge growth in one cut
Cutting several feet of mature hedge growth in one cut
Hedges.IMG_0856

One of the key advantages over a flail is the very pleasing clean neat cut, which is particularly important when managing hedges on an extended rotation.

So often I hear that if you don’t cut your hedges every year you get a “right mess” but the photos below help illustrate how clean the cut can be, and how strong regrowth is behind the cut.

Cost also comes into play, with the finger bar costing £2400 it was, in my view, not overly expensive, albeit our finger bar cutter is a little on the light side for our management objectives, the key is not to be in a rush and to learn the machine’s limitations.

Hedges..IMG_0876
Hedges...IMG_0878

The brash left behind has both advantages and disadvantages, depending on your personal viewpoint. I try to make a single cut so each piece of brash is as large as possible, making it easier to then bulldoze cut material together with the excavator blade and/or the front toothed bucket.

If the ground is very wet, this is often done at a later date, being mindful of breeding birds.  I have been pleasantly surprised how effective this actually is as the material acts as a rake. Note we have no roadside hedges. Touch wood, we have had no issue with thorns, either with cows or tyres as we use the tracked digger to clean up.

An advantage of the long sections of brash is you can actually clean up, compared to a flail which sends material everywhere. We don’t have sheep, but if we did, thorns might be a concern due to sheep’s ability to find danger!

Hedges cut on a 3-4 year rotation generate a lot of material, as the photos illustrate. The tidiest approach is to burn it, however that would be too conventional! As a result, where there are gaps in the hedge, the brash is used to fill them to discourage livestock and people with dogs (picture, left below) or to make habitat piles (picture, right below).

Where ditches are fenced off (our ditches are small and seasonally dry) I tend to leave the brash in situ to provide some dead wood but to also potentially slow flow and to help intercept sediment. Using the material from the hedges adds to the sustainability of our approach.

If I was a workshop tinkerer I would be making a Bailer to somehow get the material into our log biomass boiler!

Hedges.......IMG_3699
Hedges....IMG_3257

The second attachment for the excavator is a TMK tree shear, which again is operated via the third service. This machine basically grabs hold of a tree, branch or shrub pulling it across a cutting blade. The cut off material can then be placed in a pile or wherever the operator wants.  As with the finger bar I try to fill gaps with the material, and section out any timber for logs, but ultimately some of the brash is burnt. This machine has really helped with managing some of the bigger grown-out hedges.

The speed and ease of coppicing it provides is amazing and clearing up the material is so easy as you have hold of it in the comfort of a cab.  A key lesson is to take a long-term approach and not to blitz all the hedges at once just because you have a tree shear and have to get all CS capital works done in 2 years - owning a tree shear should perhaps come with a licence! Manage hedges over your lifetime not on an annual basis.

It should be noted that with larger material the tree shear/ cut is not especially "clean", however this is where compromise sometimes come in. With full coppice we tend to finish off stumps with the chainsaw to limit the ripping effect of the shear (picture below).

I am also playing with part managing grown out hedges through part-coppicing, digger-laying and generally mixing up diversity of management.

Tree shear on Alder

The ultimate sign of success, however, is the species using the hedges. We are perhaps culpable of not doing enough survey work, however the thing we have really noticed is the increase in yellowhammers.

This will not be solely down to hedges as we have winter bird food and supplementary feeding - however the hedges are a key component in the ecological jigsaw.

Yellowhammer Emberiza citrinella, adult male feeding on grain at Hope Farm,  April 2002

Why we take this approach to hedgerow management

Our approach comes down to circumstance and objectives and will not be for everyone.  Our aim is to:

  1. Maximise the ecological value of hedges by allowing flowering for pollinators and fruiting for birds and small mammals by pushing back cutting dates to as late in Feb as possible and extending the cutting cycle to have 75% of hedges in berry and flower production each year.
  2. Have control over hedgerow management, allowing flexible and responsive approach to management based on ground conditions and most importantly what I see while cutting the hedge. This is particularly relevant to hedgerow trees and allows me to first spot them and then not cut them.
  3. Have a diverse range of hedges at different stages of succession from regenerated through planting and coppicing to mature with future hedgerow trees establishing.
  4. Incrementally cut the hedges so they are not cut to the same point, so they expand overtime ultimately leading to being coppiced and the process starting again.
  5. Have hedges that provide shelter, function as a livestock barrier and contribute to the agricultural success of the farm.
  6. Minimise ground disturbance/compaction

The key thing however is mind-set, an uncut hedge to me no longer looks messy, whereas a bonsai flailed hedge looks like a massive missed opportunity. As farmers we tend to hate bare fallow and that’s how I feel about an annually flailed hedge when it is not getting the chance to produce a crop of flowers and/or berries

Hedge to right coming into third year after cutting has comparable flowering with unmanaged hedge to left
Hedge to right coming into third year after cutting has comparable flowering with unmanaged hedge to left
Same hedge close up - note, honeysuckle
Same hedge close up - note, honeysuckle

Sources of further information/ advice

Delivering Championing the Farmed Environment (CFE) events, in my role as Northern Co-ordinator has really helped develop my understanding of hedges over the years.

Events with Steven Falk, an excellent entomologist, have really highlighted the value of hedges and particularly the flowering cycle of hedgerows for pollinators early in the season, before habitats like nectar mixes and meadows come into play.

Hedgelink also produce excellent information about hedgerow management which we have used in events.

Encouragement received from Chris Tomson, who was our local RSPB adviser has also fostered a greater interest and understanding.

Case Study: Carabid beetles for natural-enemy pest control

Author: Kelly Jowett:

If there was an agent acting within your crops that could reduce eggs and first instar larvae of the cabbage root fly by up to 90%; reduce emerging wheat blossom midge by 81%; and reduce seed stock of crop weeds in the range of 65-90%, then I’m sure you’d want to keep it in there. Well, with a little effort you can have this voracious destroyer of pests working across your farm. Carabid beetles, sometimes known as ground beetles, eat ALL major crop pests, and weed seeds too, and are present in all farm habitats across the UK. This makes them ideal agents of natural enemy pest control.

Natural enemy pest control is a bit of a mouthful but is just what it describes: the eating of crop pests by the predators that would control them in a natural system. The problem for natural enemy pest control is that we are not dealing with a fully natural system. Since the post-war agricultural revolution, farmland has been subject to tremendous change. Over time this has caused substantial decline in the populations of carabid beetles and other natural enemies. Unfortunately, pest species are adapted to bounce back quicker - especially since large crop areas are ideally suited to support population booms. Whilst pesticide sprays are necessary in this system, they compound the problem - hitting the predators as well as the pests, added to associated resistance building.

The importance of biodiversity

Carabid beetles are incredibly variable. Of the 350 species in the UK, 30 of these are common in farmland. They range in size from 2mm to 3cm in length; some can fly long distances, some run up to 16cm per second; some breed in the autumn, and some breed in the spring. Each has their own habitat preferences, meaning that they are active at different times, tolerate different weather and farm management practices, and are better at eating different crop pests. Therefore, having a diverse range of carabid species will mean that you have the best chance of effective pest predation.

So what can we do to help boost carabid numbers and diversity?

Luckily carabid beetles are well studied and we already know a lot about what they need to thrive. We can break this down into areas to feed, areas to breed, and areas to shelter.

Areas to Feed

Of course we want them to feed in the crop or pasture area when pests are there- but pests are not there all the time (luckily for us!) to support the carabid beetles needs. So semi natural areas are essential to provide the invertebrate and plant resources for all year round food. Conservation headlands, grass/ flower margins, beetle banks and taking field corners out of management, can all provide these close to productive areas, so carabids can move quickly into the crop to eat the pests they prefer, when they appear.

Areas to Breed

Carabids lay their eggs in the soil, hatching into larvae- which take around 6 months to grow, before they pupate and emerge into adult beetles. The larvae are actually predatory on crop pests too, and eat more than adults as they need a lot of protein to grow. Some larvae also eat weed seeds, which is particularly useful as they live in the top soil levels in the crop area. To help larvae grow undisturbed in crop areas, minimum tillage systems may be useful.

Areas to Shelter

Carabids have two main periods when they need shelter: hibernation, and aestivation, which is a summer rest period when conditions are too hot and arid. At these times, the beetles take advantage of permanent habit with structure that creates a protective microclimate- such as hedges, ditches, banks, and at a small scale the tussocks created by some grasses.

Another important aspect is the shelter from machinery and chemical applications. These can cause direct mortality, or affect the carabids ability to feed and breed, so safe areas near to crops allow some beetles to thrive and repopulate when such management is necessary.

Linking up farm habitats

To preserve or enhance the diversity of carabids on your farm it is important to have a range of habitats, but also for them to be linked up. Firstly populations need those seasonal and foraging movements, but as conditions change, different species can immigrate into your farm from surrounding areas to boost your assemblage of species. Carabids move in the landscape in a variety of ways, flying species will use habitats as stepping stones, whilst running species may need ‘corridors’ of hedges and margins to encourage them to move around the farm.

Farm habitats for beetles. a) grass and flower margins, along with hedges provide food resources year round, and connect other habitats;
 b) beetle banks create stable resources in the centre of fields, to encourage beetle presence in crop areas;  (c) Peter Thompson
c) taking corners out of management encourages scrub and tussocky grasses- ideal for sheltering carabids.

Farm habitats for beetles: a) grass and flower margins, along with hedges provide food resources year round, and connect other habitats;  b) beetle banks create stable resources in the centre of fields, to encourage beetle presence in crop areas;  c) taking corners out of management encourages scrub and tussocky grasses- ideal for sheltering carabids.

But there is still work to be done

Although scientists have done a lot of research on carabids, there is still a lot we don’t know. My recent work has shown that different species are associated with different landscape features such as field boundary habitats, crops, soils, and management such as tillage regimes. If we can better understand which habitats are most beneficial for different beetles, it will become possible to tailor your farm habitats to get a good selection of predatory species that suit a farms particular pests.

Pitfall trapping to monitor farm habitats

Pitfall trapping is a quick and easy way to see what carabids you have on your farm, and if you do pitfall trapping periodically, you can track how the populations vary over time relative to your farm management interventions. For details see my factsheet:

 How to pitfall trap on your farm: Factsheet

Feed-back to scientists, especially me!

The main knowledge gap is how these habitats work in practice, over time. This is where we need to work with farmers closely, monitoring farm habitats, seeing what works, where, and why. But also, crucially, we need to know which interventions fit well into your farm business. Even if something works for beetles, if it’s going to be difficult for farmers to apply, it will not be widely applied!

Which leads me on to my plea: I need farmers to take my survey!

Watch my animation: Here.

Take a short introduction to ID quiz: Link to ID Quiz

Then take my beneficial beetles survey to tell me your opinions on carabids, management that may be useful for them, and monitoring. Link to survey

If you are motivated after reading this article to carry out pitfall trapping or set up monitoring on your farm, I would be happy to help with advice, and support with verification of carabid identification.

Email : Kelly.jowett@rothamsted.ac.uk or contact me on twitter: @kelly_jowett