Hedging on Portsdown Hill
A well-managed hedge provides a rich habitat for wildlife and an attractive alternative to a wire fence. If a field's boundary is marked by a dense and varied line of bushes and trees, it supports hundreds of species of insect, bird and mammal. There are flowers in the spring and summer, there are berries in the autumn and there is shelter in the winter. Birds nest in them; invertebrates over-winter in them and plants thrive in them. A hedge is also a corridor that connects the habitat of woodland creatures as they move across the landscape. In an intensively farmed countryside, a hedge and its uncultivated grassy verge offer a lifeline to our fauna and flora.
Like any ecosystem hedges are dynamic, they change with time. Left unmanaged they grow upwards and outwards. They become expanding bands of scrub that obscure access and creep across fields. Whilst the considerable biodiversity associated with them benefits from this expansion it interferes with the use of the field, so they are constrained to a width of 2 metres or so.
Until the 1960's, hedge management was largely a winter job carried out by underemployed farm workers at a quiet time of year. They were kept trimmed and shaped with hand tools. In more recent times the use of tractor-mounted mechanised flails has made it all to easy to bash hedges into rows of shattered sticks. They can be cut too hard and too often and so lose vigour and eventually die out.
When manpower and skills were more abundant hedges were laid in a cycle of 10-20 years. Hedgelaying is the process of cutting the stems of the hedge plants nearly through and bending them over to form a living fence. The cut stems are staked and woven to keep the hedge stockproof. Regrowth from the stems and stumps produces new shoots that fill out the hedge in subsequent years. The shoots arising from the stumps become big enough to be laid themselves to form a new living fence the next time the hedge is laid. It is a cyclical process that rejuvenates the hedge.
There are many styles of staking and weaving the stems that reflect the local farming practice. For instance sheep areas of southern England the characteristic hedges are dense and rather low. In the Midlands, hedges are taller and robust to contain cattle.
Hedges on Portsdown Hill
Having completed the fencing of the Hill in 2006, the volunteers are now able to concentrate on the more aesthetically-satisfying task of hedge-laying.
In many places we will cover fences with hedges, which is both visually more pleasing, as well as providing habitats and more effective barriers against breaching the fences. We also plan to lay hedges laid round some blocks of scrub.
Whilst much of the scrub on Portsdown is being removed, some will remain, as scrub itself provides valuable habitats for many species. These blocks of scrub will, ideally, remain undisturbed by both people and grazing livestock, to encourage the natural wildlife we want to inhabit it. To discourage this disturbance, we'll provide the scrub and its inhabitants with the protection of a hedge.
Spring 2007
Shaping the stakes
The hedging stakes are cut from the scrub being cleared anyway, and can be of most woods that provides straight, 6 foot (2 meters) stakes are trimmed to size just before use.
Laying the hedge
Live stems are used for the basis of the hedge. They are carefully cut through to about 2/3rds of the thickness of the trunk, to form a hinge. The hinge should be as close to the ground as possible so that the regrowth will have a better connectivity to the root system - as it will be closer. Once the stem is pliable enough to bend, the living trunk is laid along the line of the hedge. The regrowth will of course form the next generation of the hedge, and in the fullness of time, perhaps a decade, need to be relaid.
Stakes are driven into the ground between the lain scrub
Between the lain scrub, the sharpened stakes are driven into the ground to provide a line for the hedge.
Binders
Long, flexible 'binders' are then woven along the stake-line. These are twisted together to provide a strong and rigid line.
Trimming
Having woven the binders around the posts, the hedge now has enough strength and rigidity to allow the stakes to be trimmed. This is done with either billhook or saw. The cut is a slope which is both more aesthetically pleasing, and allows rain to run off rather than puddle which would rot the wood.
Completed Hedge
Key points
- Old hedges become gappy at the bottom as trunks grow up and new shoots fail to emerge from their bases. These gaps reduce the effectiveness of the hedge as a barrier to stock, as well as its attractiveness. Laying the hedge produces a woven structure, made of living material as far as possible, which will keep animals in.
- Re-laying also prevents the bush stem getting too thick at its base. As a hedge is trimmed to maintain its height and thickness, it is not allowed to grow to the extent it would otherwise.
- However, as annual growth continues to occur, the bush stems get excessively fat to support the plant that is kept at this limited size. As growth occurs on the outside of the stem, and nutrients pass up channels just under the bark, this thickness and enforced 'stunted growth' can obstruction the channels, and thus the flow of nutrients to the rest of the plant.
- Furthermore, the roots also become old and, because they are not allowed to feed a plant of growing stature, less efficient. Regeneration of the root system, and a more 'youthful' stem and supply of soil-nutrients is encouraged by the traditional hedge-laying techniques. This involves splitting the stem near its base, and 'bending' the top-plant over. This forces refreshment of both the above-ground plant and root system, and so maintains a healthy plant at the required size. At the two extremes of over-management and lack of management, reduced diversity may occur in hedgerows.
Cultural importance
The cultural importance of hedges is reflected in their protection under the UK Hedgerow Regulations.
More about hedging can be read at www.agroecol.co.uk/Assets/Guidelines2.htm