Woodland design

The balance of tree cover with grassland areas will depend on the priorities for the site. Where timber or coppice production is a primary aim, the proportion of overall tree cover will need to be high. Where woodland grants are being obtained, the amount of tree cover must be within the terms of the grant. For amenity use, the open spaces, avenues, wide paths and other features within a woodland are of great value. For reasons of security against attack, fear of being lost, and simply because the woodland edge is often the most attractive part of a wood, most people like woods with plenty of spaces within them. The woodland edge also attracts a wide range of plants and animals. Open space comprising about one-third of the total area of the woodland gives a reasonable balance.

When designing the planting, retain any existing patterns of hedges, walls, ditches or other boundaries within the site, and give them emphasis by using them as edges to planting plots. Don’t plant densely right up to the edges of ditches and streams, but leave a margin of about 5m of bankside vegetation, with occasional trees. The edges of woodland plots, and the landscape features they create, are more important than the shape of the plot in plan view. Within the plots, plant trees at close spacings to ensure good survival, and then thin as required to create the type of woodland you want. Manage the spaces outside the plots as paths, glades, meadows, marshes or ponds.

The following table gives the numbers of trees per hectare at square spacings. It can be used to estimate the number of planting stock required, and the thinning required for final spacings.

Woodland type

Types of woodland include coppice, coppice with standards, high forest and parkland or pasture wood. These describe the traditional ways of growing trees, and refer not only to the type of woodland produced, but to the style of growth of an individual tree. These styles of growth, produced by pruning, are just as valid for small groups of trees as for a large woodland. Certain species of trees are particularly suited to each type of growth. Trees can also be grown unpruned, in which case their shape will be determined by their spacing and by factors such as soil and exposure to the wind.

Coppice

Coppicing is a method of managing trees by cutting them down every 10-30 years to ‘stools’ near ground level, from which many shoots regrow. This is an ancient system that evolved because it could be managed with simple tools, and produced long, straight poles which could be used for building, fencing, firewood, tool making and other purposes. It is a method of harvesting timber that does not kill the tree, so does not require replanting or major disturbance of the woodland floor. Where areas or ‘coupes’ are cut in rotation in a woodland, coppicing maintains the continuity of habitat within the wood. Ancient coppices are a direct link back to the original forest.

Some species respond better to coppicing than others, though all native deciduous species can be coppiced. Hazel and sweet chestnut are the most important coppice species, because they produce poles with particularly useful qualities for fencing, but willow, oak, hornbeam, lime, birch and ash are also often coppiced. Coppices can be either of mixed species, or of only one species.

Coppice management is suitable for voluntary groups, because it can be carried out with simple hand tools and produces material which is useful and easy to handle. Coppice woodlands support a wide variety of wildlife, and produce varying conditions from open glades to closed canopy, depending on stage of the rotation. Mature coupes should be mainly clear of undergrowth, making them pleasant to walk through and explore. Coppices are wonderful places for children to play. Minor damage to coppice stems is not a problem, as the ‘stool’ will sprout again. The need for rotational management is usually an advantage, which maintains community involvement in the woodland.

The planting method is as described above, with plants 2.5m to 3m apart. keep the plants weeded for the first 3-5 years. The first coppicing can be done when the trees are between 7 and 10 years old, preferably in March or early April, by cutting the trunk or stems down to ground level.

Coppice with standards

This is another traditional system of woodland management, where some trees are left to grow to full size, originally to provide large-size timbers. Oak is the usual standard tree, with between 30 and 100 trees per hectare, with coppice beneath. In commercial woods, oak is usually left for 5-6 coppice cycles, or 100-130 years, and felled at the time the coupe is cleared. In non-commercial woods, oak can be left to grow on to a great age. Most other native deciduous species can be used as standards, with the exception of beech, whose dense shade suppresses the growth of coppice beneath. To maximise coppice growth beneath, young standard trees should be pruned to remove side shoots and develop a strong leading shoot, to produce tall-stemmed, high-canopied trees.

High forest

In this type of woodland, trees are grown to their full height to produce a high, close canopy. This type of growth can be encouraged by choice of suitable species, and by pruning of the side branches for the first few years of growth. This encourages strong upward growth and a clear straight stem. On some fast growing species such as poplar or ash, quite spectacular growth rates can be achieved, producing a ‘mature’ look to the wood within a decade. For urban woodlands, this reduces the duration of the thicket stage, when the young woodland is too dense to see or walk through, and which tends to be unpopular in residential areas.

Parkland or pasture wood

Pasture woods are an ancient system of management, allowing multi-use of land. The pasture provided grazing for stock or wild animals, while the trees provided timber for fuel and other purposes. By pollarding trees, which is like coppicing above head height, poles could be produced out of reach of grazing animals. Other trees were grown as wide-spreading standards. Grazing removed undergrowth and prevented regeneration. Where trees needed replacing, natural regeneration or planted stock would need protecting against grazing animals.

This type of landscape is attractive, and has always been favoured for recreation. The landscaped parks of Capability Brown and the urban parks which followed were an imitation of this type of landscape.

Small scale planting

These woodland types and forms of growth can be followed even on the small scale, to give variety and character to urban planting. A few hazel, sweet chestnut or ash trees planted in a group can form a small coppice, sufficient to produce bean poles for a garden.

Willows for pollarding grow very quickly from cuttings inserted in the ground. Cuttings as large as 100mm diameter will root, and depending on growth, can be pollarded after about 8 years. Pollarded poles can be used for garden stakes, and pollarding is a useful way of controlling the height of trees in limited spaces.

Where tall trees are not going to cause problems of shading, strong upright growth in species such as cherry, ash, beech and lime can be encouraged by pruning, to produce tall, high canopied trees.

Woodland plots

Most sites will divide naturally into various areas which have different characteristics of soil, aspect or existing vegetation. Streams, paths and other linear features will also divide the site. For each plot, choose a species or mixture of species and a woodland type which will give a strong character to each of the plots, to give variety to the site. Species and woodland type can be repeated on similar plots to avoid creating too much of a patchwork.

Planting mixtures

Within each woodland plot, limit the choice of species to two or three of the main broadleaves, mixed with three or four other broadleaves as nurse species or understorey species. Alternatively, a simple monoculture of one main species such as beech, with or without an initial nurse crop (see below), will create a visually dramatic piece of woodland. Avoid planting a large area with a random mixture of 10 or more species, which will result in a rather monotonous hotch-potch of woodland.

When planting, avoid planting different species in lines. Instead plant groups of nine or more of each species, varying the spacing to avoid lines, and emphasising the natural irregularities of the site. In later years, each group will then be thinned to leave a few or eventually a single tree from the original group of nine.

On the small scale, where only a few trees are being planted, a group of a single species, with or without a nurse crop, may prove easier to manage and more attractive than a mixed planting.

In the first few years it is crucial that trees grow well and put on good root and top growth, so that the woodland establishes quickly. Too often young trees languish for many years in untidy ‘tree planting areas’, putting on insufficient growth to be anything other than an eyesore. Maintaining a weed-free area of at least one metre diameter around each tree is the most important factor in ensuring good growth.

newly-planted trees also experience stress from exposure to frost and wind. Tolerant and fast growing species can be planted as a ‘nurse’ to improve the microclimate and protect the preferred species from exposure. They can also be useful in deflecting the attention of vandals from the preferred species. The nurse trees should be thinned or removed once the slower-growing species have become established. This may provide some income from the sale of firewood or other woodland products. In the worst case, the nurse species can be retained if the desired species fail to thrive.

Suitable nurse species include willow, common alder, wild cherry, sycamore, ash and sweet chestnut.

Successional planting

As an alternative to planting a nurse species at the same time as the preferred species, successional planting can be carried out over a number of years. Successional planting imitates natural colonisation, by gradually building up the diversity of the woodland. The shrubby pioneer species are planted first, followed a few years later by the first- stage tree species, with the climax tree species planted last. Successional planting has the advantage that shelter for the first-stage and climax tree species is provided by a diverse range of shrubby species, rather than by one or two fast-growing nurse species, so producing an ecologically more diverse habitat. However, on many urban sites there will be a desire to produce as quickly as possible a fairly open woodland, which can be seen and walked through. This is most quickly achieved by planting the preferred species with a nurse, and then side-pruning and thinning to produce rapid growth.

Successional planting may be useful on sites prone to vandalism, where robust, fast-growing and cheap species can be planted first, with losses expected, and then the more desirable species planted once the vandals have lost interest. Willow is very effective, as it will sprout from cuttings simply inserted in the ground.

In successional planting, a pioneer community of shrubs or trees is planted first. These are chosen from species which are easy to establish in open, unshaded conditions, being tolerant of wind and low humidity. Suitable species might include broom, gorse, blackthorn, hawthorn, dogwood, guelder rose, field maple or elder.

The pioneers are left to grow for a few years, and provide shelter for the first stage tree species which are then planted amongst them. First stage species might include alder, birch, wild cherry, whitebeam or ash.

Depending on growth, some of the pioneers will need to be removed a few years later to make space for planting the climax species. These are long lived species such as oak, beech, hornbeam and lime, which require sheltered conditions in which to successfully establish.

Successional planting may not be possible where grant-aid for planting is only available for a limited time.

Whether a woodland is planted successionally, or at a single planting, sensitive and well-timed management will be required in the following years for the woodland to develop its full amenity, landscape and wildlife potential. Weeding, pruning and thinning must not be neglected or the future value of the wood will be greatly reduced.

Edge planting

Particularly on the windward edge of exposed sites, close planting of shrubby species will shelter the developing wood, and provide valuable wildlife habitat. This will however have to be balanced with the desire for open and user-friendly woodlands. Where edge planting is feasible, plant species such as hawthorn, blackthorn and guelder rose at spacings of about one metre, to form an informal hedge on the windward side of the planting area. On the woodland side of the hedge, plant drifts of the smaller broadleaves such as crab-apple, hazel, birch, rowan, holly or willow, to create a sheltering effect for the main tree species within. In the short term, the shelter from the edge planting will help the young trees to establish. If the edge planting can be retained in the long term, it will create a sheltered woodland of greater value to wildlife than an open and draughty woodland.

Where vandalism is likely, edge planting of dense and prickly species such as gorse, bramble, hawthorn and blackthorn can also be used to hide and block access to the young trees. Allow two or three seasons for the edge planting to establish, before planting the tree species.