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The Go Wild Festival ran at Kew and Wakehurst place for the summer of 2003. As such many of the festival features can no longer be seen in the gardens, but this website has been kept to give visitors access to wealth of information developed to support the festival.

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Charcoal production and coppice management at
Wakehurst Place

For hundreds, if not thousands, of years Britain's hardwood forests have been sustainably managed for the production of timber and fuel, including charcoal. The intense heat produced by burning charcoal made it an important fuel for iron smelting, which has been carried out on an industrial scale in Britain as far back as the Roman Empire. However, the widespread use of fossil fuels in the nineteenth and twentieth centuries led to a dramatic decline in charcoal production in Britain. Consequently many of the woodlands which had been carefully managed for this valuable economic product fell into disrepair or were destroyed in an attempt to secure a more profitable use of the land.

Coppicing

Filling the charcoal kiln

Much of the charcoal was produced from woodland that had been coppiced. This ancient practice, whose name is derived from the French verb Couper (to cut), involves cutting shrubs and trees to ground level and regularly harvesting the shoots which regrow from dormant buds in the stumps and roots. Traditionally a limited number of trees, known as standards, are retained in coppiced woodland for the production of larger timber. A balance of standards to coppice is then struck in order to ensure both crops have adequate light to grow. If the shoots are not cut back on a regular basis they become over-mature, often leading to a reduction in vigour, decay, death, or a reversion to high forest. Miraculously, however, when old coppice shoots are cut back the whole stump can be rejuvenated.

Which trees can be coppiced?

Most British native broadleaved trees and shrubs can be coppiced and the time between cuts depends on both the species and the product required. Hazel (Corylus avellana), for example, is typically coppiced every 7-10 years to produce pea sticks, bean poles, thatching spars, hurdles and fuel. Sweet chestnut (Castanea sativa) is usually cut at 15 years for fencing, whilst oak (Quercus robur) can be left from 25-35 years for firewood and charcoal production. Other important coppiced trees in Britain include alder (Alnus glutinosa), beech (Fagus sylvatica), birch (Betula), field maple (Acer campestre), small-leaved lime (Tilia cordata), sycamore (Acer pseudoplatanus), willow (Salix spp.) and wych elm (Ulmus glabra).

Some coppiced woodlands are ancient woods descended from the original primeval woodland cover, whilst others are recent plantations. A coppiced small-leaved lime at Westonbirt Arboretum, Tetbury, is estimated to be over 2000 years old. Over this period it has radiated from a central stump which has long since decomposed and its outer stems form a circle appearing rather like a fairy ring. An individual tree of this species would be expected to survive only a few hundred years; its increased longevity is due to the rejuvenating influence of coppicing.

Coppicing and its effect on wildlife

The regular cycle of coppice management creates an open woodland habitat favoured by many plants and animals. In over-mature coppice, the dense canopy reduces the light available to plants on the woodland floor and only the most tenacious survive, often by growing in late winter before the canopy casts its dense shade. Following coppicing, the extra light that reaches the woodland floor stimulates a riot of colour from various native plants as they burst into flower. These may include daffodils (Narcissus pseudonarcissus), bluebells (Hyacinthoides non-scripta), wood anemones (Anemone nemorosa), violets (Viola riviniana), wood spurge (Euphorbia amygdaloides) and primroses (Primula vulgaris). These plants which can survive vegetatively under the old coppice canopy are soon joined by others like foxgloves (Digitalis purpurea) and St John's worts (Hypericum) which germinate from buried seed.

A wide range of invertebrates thrive in the warm microclimate and on the bonanza of food plants in young coppice. Some species have declined alarmingly with the reduction of coppicing and the future survival of several butterflies including the rare heath fritillary may be dependent upon a return to this traditional woodland management.

As the coppiced shoots regrow, bramble often invades providing dense cover for small mammals and birds such as the garden warbler and nightingale. The rare dormouse also benefits but care must be taken to ensure that the coppice cycle is long enough (10-15 years) for its food plants, especially hazel, to flower and fruit.

Coppicing is, however, not a panacea for all wildlife conservation and should be a part of a planned woodland management programme. For example, some birds and invertebrates including the speckled wood and white admiral butterflies and the robin enjoy the deep shade and structure of neglected coppice. Others enjoy the dead wood habitats and larger trees provided by standards or high forest.

Coppice at Wakehurst Place

In pursuit of Kew's objective to help ensure better management of the earth's environment, many of the woodlands at Wakehurst Place are being restored by bringing over-mature coppice back into a matrix of sustainable woodland management. Care is taken to balance the habitat requirements of its rich communities of plants and animals with the harvest of woodland products. Using traditional skills, hazel with standards is cut on a 10-12 year cycle to provide pea sticks to support the herbaceous plants at Kew and Wakehurst Place whilst ash and other species are cut on a 20-30 year rotation to produce 'BAR-B-KEW' charcoal.

How is charcoal used today?

In Britain today, charcoal is used as fuel for domestic barbecues, in fireworks and in medicinal biscuits. As it can absorb gases and impurities, it is employed in chemical, water and vodka filtration. Approximately two thirds of the estimated 60,000 tonnes of charcoal sold in Britain every year are used in barbecues. Of this vast quantity only 3 per cent (1,800 tonnes) is produced in England. A large proportion of the remainder is derived from unsustainable harvesting in the tropical forests and mangrove swamps with the cheapest imports coming from South-east Asia. This is particularly disturbing when one estimate suggests that there is 800,000 tonnes of low value wood including over-mature coppice in the south-east of England alone. This wood is currently of little economic value but could be used for the production of high quality British hardwood charcoal.

How is charcoal produced?

Charcoal production is dependent on heating wood without enough air for complete combustion. Under these conditions, water is expelled from the wood and volatile substances such as tars and oils are released, leaving charcoal containing up to 90 per cent carbon. In most charcoal production processes, some of the wood in the kiln is burnt to produce the necessary heat. If thoroughly air-dried wood is used, ideally with a moisture content below 20 per cent, then 4 tonnes will yield 1 tonne of charcoal. This yield is halved if unseasoned timber is used since a higher proportion of the wood in the kiln has to be burnt to provide the required heat.

Many different kilns are used throughout the world. Some, known as earth kilns, utilise only materials from the woodland to seal them. At Wakehurst Place, a less labour-intensive portable steel kiln is moved around the woodlands to each new coppice block. Other initiatives in Britain could lead to huge static kilns to which timber growers take their coppiced wood.

Charcoal from Wakehurst Place

At Wakehurst Place up to 3 tonnes of BAR-B-KEW charcoal is made each year. Like other British hardwood charcoal, it has a high carbon content which makes it easy to light and quick to reach a high cooking temperature. These qualities make it a superior product to most imports and it provides an alternative to charcoal produced from endangered sources such as tropical rainforest and mangrove swamps. Its retail is helping to perpetuate a traditional practice and will contribute to wildlife conservation at Wakehurst Place.

Additional sources of information

Aarron, J., 1980. The production of Wood Charcoal in Britain. Forestry Commission Forest Record, 121. HMSO
Anon., 1993. Statistics of charcoal imports. Centre for Environmental Information, 24 Roseberry Road, Cheam, Surrey. SM1 2BW
Buckley, G.P. (ed.), 1992. Ecology and Management of Coppice Woodlands. Chapman and Hall
Fuller, R.J. and Warren, M.S., 1990. Coppiced Woodlands: their management for wildlife. Nature Conservancy Council

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