What's wrong with our Hedges?
Where did all the trees go?
60 or so years ago, to someone looking across the landscape of lowland Britain it would probably have seemed quite well wooded, despite the fact that the country, still one of the most tree-depleted in Europe, had far fewer woodland trees in the 1960s than it does now.
The reason that the countryside appeared well wooded was largely down to the large number of mature trees that stood in so many of our hedgerows, with elms perhaps being the most frequent. Being a light-demanding species that doesn’t generally thrive within woodland, elms are particularly well suited to growing in hedgerows where light and space is freely available. Spreading easily by root suckers and frequently developing to considerable size it came to dominate the landscape across wide parts of the countryside of lowland southern Britain.
Hedgerow elms in the 1960s
But then came Dutch elm disease:-
Dying elm trees; a typical scene from the late 1970s
The outbreak starting in the early 1970s swept across central southern England and by the 1980s most mature English elms had died; something like 30 million trees had been killed, an enormous number of which, perhaps 50% or more, had been growing in hedgerows. Their loss transformed the landscape of Britain.
Typically, these were well-established trees that had been growing for 50, 100 or even more years and had grown to be substantial trees by the time that tractor-mounted hedge-cutters were introduced after the 1950s. In those early days the machines simply had to work around these large obstacles. However, once they had been laid low by Dutch elm disease, the hedge-cutters had a clear, unobstructed run. The result was that that any sapling, of whatever species, that poked its head up above 1.5 or 2 metres was immediately decapitated by the next passage of flail.
Several million hedgerow elms had been lost and precious little replacement planting was carried out.
The result was, and to a great extent still is, miles and miles of uninterrupted, boxy hedges. Tidy to be sure, but very largely treeless.
Some trees of other species such as oak and ash remained where they were already well-established, but the arrival of Chalara dieback of ash over the past few years is causing a further diminution of our hedgerow trees, with millions of ash trees being lost over and above the millions of elms lost in the 1980s. And all the while the near universal use of tractor-mounted flail cutters has largely prevented any new trees establishing to replace all of those lost.
The disappearance of so many trees has not only degraded the appearance of the countryside but has also resulted in a significant loss of all the other benefits that trees provide, depriving wildlife of shelter, food and nesting sites. Hedgerow trees are essentially open-grown, with more wide-spreading crowns than trees in woodlands and as such they offer a different but complementary set of benefits to those provided by woodland trees, supporting different populations of insects lichens and other organisms; certain species of bats favour trees outside woodlands, as do a number of birds, which also appreciate them as song posts. They also represent ‘stepping stones’, providing links between areas of woodland.
Planting new trees to try to make good all the losses from our hedges, both past and ongoing, should be a high priority. It is, to an extent, recognised as such by the government insofar as it offers a grant for planting standard hedgerow trees: the grant is hardly generous (£19.06 per tree at the time of writing) and doesn’t even begin to reflect the true value of such trees, but it is something. More details can be found HERE.
Grants for planting hedges AND trees are available under the Woodland Trust's admirable MOREhedges scheme, which can provide grants to cover up to 75% of the cost if 100 metres or more of new hedging is planted whilst allowing a large tree to grow every six metres. See HERE for details.
The Tyranny of the Flail
Back in the day...
For generations, the hedger (also known as a hedge caster, hedge cutter, hedge layer and indeed, ditcher) was the worker responsible for maintaining hedges, banking up earth with a spade to form hedge foundation, planting hawthorn and other hedge plants, carrying out repairs it by inserting cuttings into gaps and, of course, trimming them as necessary and, at appropriate intervals, laying or pleaching them. Up until the first half of the 20th century almost all agricultural field work was carried out using horse-power or by hand with hedge-cutting being carried out with hand tools such as billhooks and long-handled ‘slashers’. It was a labour-intensive and time-consuming process that would occupy much man-power over the winter months and, with many other jobs often taking precedence, hedges were generally cut with far less frequency than tends to be the case now. The longer intervals between cuts meant that hedgerows tended to be larger and more unruly but that they also provided much wider opportunities for all sorts of birds, insects and other wildlife.
Click the link to see an instructional film, made by the Realist Film Unit for the Ministry of Agriculture in 1941, demonstrating the craft of hedge laying.
Towards the end of the 19th century the first tractors began to appear and mechanisation of many agricultural processes became more and more widespread as the twentieth century progressed. Mechanised hedge-cutting was a relatively late development, with the world’s first tractor-mounted hedge-cutter being put on the market by McConnel in 1948.
These relatively slow and cumbersome machines were developed and improved until mechanical hedge cutting became more or less universal. Modern, hydraulically powered, articulated flail cutters, mounted on powerful tractors are now familiar, making short work of a task that was once slow and laborious, allowing miles of hedgerows to be cut annual basis. The once familiar unruly hedges have for the most part become things of the past, the countryside now being traversed by straight-sided boxy hedges, the result of regular, usually annual cutting.
Tidy they may be, but their values, as discussed HERE, are greatly diminished.
Annual cutting greatly reduces the production of flowers, which for most species are produced on old wood rather than on new growth. The lack of flowers has a knock-on effect and is a significant contributory reason for the decline in butterflies and other pollinating insects in the countryside, while overwintering wildlife is also impacted as a result of the reduced production of the hedgerow fruits that many birds and mammals would otherwise feed on. It’s also underappreciated that the twiggy ends of the hedgerow shrubs can be home to the eggs and winter pupae of several invertebrates that will be destroyed as a result of flailing. An example is the hawthorn sawfly, a large insect as big as a bee which pupates on the tips of hawthorn shoots. Its numbers have declined steeply in line with the increased annual deployment of hedge flails.
Apart from reducing the production of flowers and fruit, years of continued annual flailing is also damaging to the hedge plants themselves, weakening them so that some may eventually decline and die, opening up gaps, while repeatedly cutting hedges at the same point results in the development of a layer of dense, gnarly growth at the top while becoming ever more bare and gappy at the base, depriving ground-dwelling creatures of cover. The tangled top-growth may provide some limited nesting opportunities for birds, but allowing a hedges to deteriorate in this way results in the loss of nearly all of the wider benefits that they might otherwise provide.
It would be quite unrealistic to expect farmers to revert to the hand-cutting of their hedges, but a more restrained and controlled use of tractor-mounted hedgecutters can make a huge difference. Simply reducing the frequency of hedgerow cutting to once every two years can lead to a significant increase in the production of flowers and berries, with commensurately improved levels of biodiversity although research has shown that allowing a hedge to grow for three seasons before cutting has been found to be even more beneficial. The Centre for Ecology & Hydrology has produced an informative leaflet which can be seen here: 'Increasing the value of hedges for wildlife with relaxed cutting regimes'.
As well as reducing the frequency of hedge trimming, other adjustments can be made to further improve hedgerow quality and productivity. Making each cut about 10cm higher and wider than the previous cut has been found to increase flower and fruit production in hawthorn, blackthorn and bramble by 2-3 times, providing for an increased diversity of butterfly and moth species and even more berries for overwintering wildlife. Altering the shape of the hedge can also make a difference: a rectangular hedge shape with vertical sides typically results in one side being heavily shaded whereas cutting to achieve an ‘A-shape’ form with a broad base tapering upwards to the top allows plenty of light to the lower parts. This helps to promote dense growth, especially at the base of the hedge where it is vital for providing protection, food and shelter, particularly for small mammals. Light falling on the sloping sides also encourages overall density, providing plenty of nesting opportunities for breeding birds, while the sloping sides also form an aerodynamic form allowing wind to flow over it with minimal turbulence. It is also extremely helpful to maintain a grass strip beyond the base of the hedge as this helps to protect the roots of the hedge from damage by close cultivation
The Tyranny of the Tube...
It is to be applauded that much new hedge planting has been undertaken over recent years, no doubt due in large part to the various GRANTS that have been made available. However, there must be some concern for the proliferation of plastic rabbit guards. There is no doubt that rabbits and voles can be a real problem, nibbling at the tender bark and killing plants if they girdle them and combat this, rabbit guards
have become more or less universal since they were first introduced in the late 1970s with hundreds of thousands of them having been used on young hedging plants.
It is perhaps worth asking, the question, if rabbit guards are so essential to the successful establishment of a hedge, how did former generations manage to establish all those hedges that were around before the 1970s? There must have been some losses, but these were evidently insufficient to prevent hedge establishment, although no doubt such losses as may have occurred were made good by the process of ‘beating up’, going round in subsequent years replacing plants that had been damaged or lost.
It can’t be denied that protecting tender young plants from the depredation of rabbits and other small mammals with plastic guards may prevent some losses. The problem is that the guards used are rarely if ever removed. The advice is always to remove them after a couple of seasons but this rarely happens. Rather, they remain long after they cease to serve any purpose, merely littering the countryside: It's only too common to see fully established hedges with the remains of split and broken tree guards all around. After several years or even decades, the redundant guards break up and disintegrate.
So-called ‘photo-degradable’ tubes disintegrate more quickly under the influence of light; however, whether quickly or slowly, the plastic still end up as fragments which besides being unsightly will in time break down to become ‘microplastics’ in the soil, where they can have a significant impact on wildlife. The impacts of microplastics on wildlife and the environment are widespread and only now beginning to be appreciated; it has even been established that earthworms, which are essential for a healthy soil environment, may have their fertility reduced by up to 50% as a result of ingesting microplastics.
A factsheet outlining what microplastics are and how they can affect the environment is available for download HERE.
Tree and rabbit guards are available that are manufactured using recycled cardboard and even materials such as sheep’s wool, treated with additives to make them water resistant. These are claimed to be truly biodegradable; so far, however, these are more expensive and are very far from being universally used.
Another consequence of using rabbit guards is that they tend to suppress the development of low side shoots, with the result that the plants develop bare stems, with dense growth only at the top, a sort of minimal 'hedge on stilts', a form that is only exaggerated by subsequent flail-cutting. The result is that there is no low cover for small mammals, much reduced opportunity for nesting birds and almost no likelihood of flower and berry production. Such hedges also offer very wind resistance and offer no significant impediment to soil erosion.
So... What is to be Done?
It's one thing to be critical of how hedgerows are planted and managed; the question is, how can practices be improved?
Firstly: Plant More Hedgerow Trees!
Sapling or regrowth from within an existing hedge that is strong, reasonably straight and not too damaged by previous flailing can be selected and clearly identified for retention, so they are not topped-off during routine cutting. They would have to be clearly marked by, for example, a stake and tag so that they are easily visible to the operators of hedge-cutting equipment. As often as not, these will be contractors, so they must be fully briefed to watch out for saplings that ae to be preserved.
Alternatively, young trees can be planted into existing gaps in the hedge or, if no suitable gaps are present, create space by creating notches by clearing about 1 metre of hedge and planting the new trees into that. Trees could also be planted alongside the hedge where this is practicable.
The Forestry Commission has produced a booklet providing detailed information on the Establishment of Trees in Hedgerows, which is available for download HERE. The website Hedgelink.org.uk provides a wealth of information on all aspects of hedges, including a leaflet called Hedgerow trees: answers to 18 common questions - download HERE.
Secondly - Consider, Are rabbit guards really necessary?
I would suggest that it’s high time that the universal use of rabbit guards for new hedges needs to be rethought. As pointed out above, many thousands of miles of hedge were successfully established over the hundreds of years before rabbit guards were introduced.
Are they really needed now?
Are losses caused by rabbits really so great as to justify the undoubted harms that result from their use, the litter and plastic pollution they result in and the distortion they lead to in the young plants?.
I suspect not.
And lastly; apply better Hedge Management Regimes
Adopt these three simple measures:
Promote flowering and fruiting by trimming hedges on rotation, cutting only once every three years or more.
Increase the cutting height on each occasion by 10–15cm to improve shrub health and promote better flower & fruit production.
Aim to create an A-shaped profile to the hedge and encourage good cover at the base; maintain a wide, grassy margin.
After 20 to 40 years, even well-managed hedges will begin to deteriorate, becoming gappy or bare at the base. When that begins to happen hedge-laying or pleaching is likely to be necessary. However it may also be appropriate to coppice the plants, cutting them all down to above ground level to encourage them to produce new dense growth, which may in turn be laid once it has grown up to a suitable size.
For details on all aspects of Good Hedge Management see The Complete Hedge Good Management Guide
Other References:
Many leaflets and other hedge-related information is available from the Hedgelink website at www.hedgelink.org.uk, including the DVD
“A cut above the rest: managing hedges for the future”
Farmers keen to improve biodiversity on their farms can easily provide valuable habitats for farmland birds and butterflies by using Arable Options in Environmental Stewardship; Natural England, together with Defra, Syngenta, RSPB and the Wildlife Farming Company, have produced a short information film entitled “Growing Farmland Wildlife”. The film is available to watch via YouTube