British Woodlands - A Brief History Content from the guide to life, the universe and everything

British Woodlands - A Brief History

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Clitocybe clavipes mushrooms.

Woodlands are one of the most iconic and well-loved features of the British landscape. Although they are cherished, however, their origins and nature are poorly understood by most British people; they are in fact far less ancient and far less natural than is widely believed.

Origins

While there are forests in some parts of the world that are millions of years old, Britain's woodlands date back little more than 12,500 years. Prior to this Britain was largely treeless. Much of the country was covered by ice with open tundra to the south. As sea levels were much lower than at present1, Britain was still linked to the near continent, and as the climate warmed at the end of the last Ice Age, plants and animals were able to migrate into the country across what would become the English Channel and southern North Sea. The first trees to arrive were the tough species found in taiga (arctic) woodland – birch, aspen and willows. As the taiga moved north, it was followed by the Scots pines that form Britain's boreal (northern coniferous) woodland and then the characteristic species of temperate broadleaved woodland – oak, hazel, alder, holly, ash and beech. Late arrivals were lime, field maple and hornbeam. In all, 32 species of tree and ten species of large shrub arrived during this period and these are our only native species. By 8,000 years ago, sea level rise had cut Britain off from the Continent and no more tree species were able to arrive by natural means.

The Wildwood

By the time Britain was cut off from the Continent, the permanent ice was long gone, as were the ice-age mammoths and megafauna. The tundra was all but gone with the exception of the alpine arctic habitats of the Cairngorm Plateau and the far north of Scotland. Most of the country was covered in trees. Taiga-like birch, aspen and willow woodland cloaked the flanks of the highest mountains, and much of the Scottish Highlands were dominated by the open-structured Scots pine woodland of the Caledonian Forest with heather, bilberry, rowan and taiga species growing between the pines. Southern Scotland, England and Wales were dominated by broadleaved temperate woodland. Oak-hazel woodland dominated the north and west of this area, with lime woodland dominant in the south, the English Midlands and the drier parts of East Anglia. In southwest Wales and the far southwest of England, hazel-elm was the dominant woodland type. In waterlogged areas including the extensive wetlands of the Fens and the Somerset Levels, alder and willow 'carr' woodland was the norm. All these woodland types would have been diverse mosaics of different tree species rather than uniform monocultures of one or two species.

A stag beetle

These broadleaved woodlands have a dense continuous canopy during the summer months. As a consequence of this, most woodland floor plants burst into life early and flower during the spring, giving a brief burst of intense colour before the trees come into leaf and more shade-tolerant species like bracken and bramble can swamp them out. Over-mature, dying and dead trees were more common than in modern managed woodlands, creating important dead wood habitats for fungi and many insect species.

The Wildwood was inhabited by aurochs (the wild ancestors of cattle), wild boar, red deer, roe deer, red squirrels, wolves, brown bear, badgers, foxes and a range of small mammals and birds. Grazing aurochs, rooting wild boar and falling trees would have created glades and some areas of more open-structured woodland, creating habitats for plants and insects that favour sunlit areas. In wet areas, beaver would have created areas of open water and marsh supporting wetland species.

Humans and the Wildwood

The earliest archaeological evidence of humans in Britain dates back an astonishing 700,000 years. During the Ice Age, however, there were long periods when humans were not present and periods when occupation was sporadic. Continuous occupation did not begin until people arrived from southern Europe at the end of the last Ice Age. These Middle Stone Age people were semi-nomadic hunter gatherers and although they did hunt woodland animals and gathered hazel nuts and other woodland plant material, archaeological evidence indicates they tended to stay on the coast and along river valleys, avoiding the deep woodland. The human population of Britain was small and is estimated to have been in the low thousands. They may have created temporary woodland glades to encourage game and useful wild plants, but in general their impact on the Wildwood was minimal.

End of the Wildwood

Humans first had a major impact on the Wildwood when agriculture arrived in Britain more than 6,000 years ago. It was not possible for New Stone Age farmers to grow wheat and barley or graze cattle, sheep and goats in dense woodland so they began the process of woodland clearance. As agricultural production stimulated population growth which increased the need for more food, the rate of tree clearance would have increased exponentially throughout the New Stone Age. The introduction of metal tools at the beginning of the Bronze Age (about 4,500 years ago) would have accelerated this process and it is believed that by the beginning of the Iron Age (about 2,500 years ago) Britain had a population of over one million people and that 50% of all woodland had been cleared. Population growth and woodland clearance continued through the Roman and Saxon periods and into the early Middle Ages. By 1086 when William I had his newly conquered kingdom surveyed and recorded in the Domesday Book, the population was in excess of three million and 15% of England was wooded. By the early 14th Century, the population had doubled again and woodland had been reduced to a mere 10% of the English countryside.

The amount of woodland would have varied greatly across the country so that at the time of the Domesday survey, the Weald2 was 70% woodland while some areas in eastern England had less than 4% tree cover. The nature of local soils would have dictated how much woodland survived. The first areas to be cleared would have had light soils that could be tilled with wooden ploughs. These light soils would have degraded rapidly and failed, making them useless for further crops. Had these areas been abandoned they would have reverted to woodland; however, grazing livestock nibbling down young trees and commoners gathering fuel prevented this happening, creating and maintaining largely treeless heaths and moors. In areas with good soils, the amount of woodland left would have been between 10% and 20%, as woods were left in order to meet the local demand for fuel and building materials. In areas with heavy clay soils like the Weald that could not be ploughed, the woods were not cleared, but the nature of the remaining woodlands was very different from that of the Wildwood due to the influence of grazing animals and woodland management.

In spite of the population halving as a result of the Black Death and the famines of the mid-14th Century and then recovering and increasing to over eight million by the early 19th Century, the area of woodland remained at roughly 10% through the late middle ages and on to the early modern period. This was because the remaining woodlands were heavily managed and were retained as an integral part of the rural economy.

Forest and Ancient Woodlands

These terms cause considerable confusion and many people fondly imagine they indicate areas that are remnants of the Wildwood. The truth is rather different. The definition of ancient woodland in the UK is a wood that has existed continuously since 1600. Forest was originally an Anglo-Norman term for an unenclosed royal hunting area and is first used in England in the Domesday Book. So most 'ancient forests' were large open chases that came under forest law during the Norman period. Many forests were largely treeless with a few woodland enclosures, including both the New Forest and Sherwood Forest which were predominantly heathland; so the myth of Robin Hood swinging through miles of uninterrupted oak woodland on dangling lianas actually has more to do with Hollywood than the 'Greenwood'.

Coppiced Woodland

Most woods were heavily managed to produce timber and other useful products. The number, type and size of trees were controlled to meet local needs using a coppice system. If a broadleaved tree is cut down it will regenerate, sending up fast-growing shoots from the stump. Coppicing exploits this by selecting the best shoots and allowing them to grow on until they reach the required size, then cutting them and starting the process again. This is an ancient practice: poles and hurdles incorporated into the Sweet Track – a 6,800-year-old wooden track-way across the Somerset Levels – are clearly the product of coppicing. Coppicing greatly increases the life span of trees: while a species like ash might normally live for 250-300 years, the coppice stool (the permanent stump) of an ash can be well over 1,000 years old.

Coppice woodlands were divided into coups (blocks, usually of about half a hectare) which were cut in rotation in order to ensure a regular supply of timber. The length of the coppice cycle depended on the species being coppiced and the use the wood was intended for. One of the commonest cycles would have been 15-30 years to produce firewood and charcoal (a vital product for industries before coal was in common use) using hardwood species like oak, ash and hornbeam. Ash and chestnut were coppiced on 12-35 year cycles to produce posts, poles and palings. One of the most useful coppice species was hazel, which on a 7-12 year cycle produces flexible rods which can be split and woven to create hurdles (fencing panels) and wattle (woven panels used in medieval house building and daubed with a mixture of clay, dung and straw to create walls). As well as being used for firewood and charcoal, oak could be coppiced on a short cycle to produce tan-bark, used by tanners to soften leather, or could be grown on to form standard trees.

Standards were the largest trees in a coppice and were scattered through each coup, well spaced to allow enough light to reach the understorey3 coppice trees. To create a standard, a single stem was selected from a stool and allowed to grow on to form a tall straight tree. This was used for timber beams or was cut into planks. Oak standards, for example, were harvested at between 50 and 120 years. These trees were vital to the shipbuilding industry, being used to create the British Royal Navy's 'wooden walls' and 'hearts of oak' that defended its shores, and the windjammers that plied its trade routes.

Coppice woodlands are excellent wildlife habitats as newly cleared coups are flooded with light, creating flushes of sun-loving woodland flowers and insects, and dense coppice regrowth is an ideal nesting habitat for many bird species. Two of Britain's most iconic species, the hazel dormouse and the nightingale, live largely in coppices.

As young regrowth can easily browsed, killing the stool, coppiced woods would have been surrounded by banks and wooden palisades to exclude grazing animals and deer, and these wood-banks can still be seen around many ancient woods.

Wood Pasture

Other woods would have been open to grazing livestock, which would have heavily influenced both the structure and species mix in the woods. As young lime, elm and hazel leaves are very palatable, while oak leaves are tough and bitter, grazing pressure favours oak, beech, hornbeam and aspen over other species and this may well explain the rapid decline of elm in the Neolithic and the change from lime to oak woodlands in southern England. Grazing also creates a park-like open-structured woodland with well spaced large trees and a ground flora of grassland and heathland species.

Extensive areas of wood pasture occurred in regions that could not support other forms of agriculture, such as on the poor soils of the Caledonian pine woods or the heavy clay soils of the Weald. In the highlands, sheep and deer grazed the heather between scattered large pines. In the Weald and elsewhere, large numbers of pigs were turned out into the woods during the autumn, to be fattened up on fallen acorns (which are poisonous to cattle and horses), then slaughtered and turned into bacon for the winter. On a smaller scale there were wooded commons, where the commoners had grazing rights while the lord of the manor owned rights to the standing timber.

Many of the best known and most iconic areas of wood pasture developed in order to manage deer for the hunt and as a source of venison – a high status food in the Middle Ages reserved for royalty and the nobility. These areas include forest (unenclosed hunting areas where the monarch owned the deer), chases (unenclosed hunting areas where nobles owned the deer) and parks (enclosed hunting areas). Commoners would have had the right to graze their animals, turn pigs out in the autumn (pannage), gather some types of fuel including small trees and gorse (estovers) and turves (turbary) and in some cases extract clay, stone, sand and gravel (rights of common) and take fish (piscary). Taking timber would be severely punished and taking deer would result in mutilation and death under the Forest Law.

Trees within wood pasture were actively managed as a source of fodder for stock, firewood, timber and other useful products. In the Caledonian Forest, pines (which do not regenerate from the stump) were periodically harvested. Elsewhere broadleaved trees where managed as a sustainable source of fodder, fuel and materials. As grazing livestock and browsing deer will readily eat regrowth on felled trees, coppicing does not work in wood pasture, so trees were managed using a pollard system. Pollarding works in much the same way as coppice except that the trees are cut between eight and 12 feet above the ground so that the regrowth is beyond the reach of browsing animals. As with coppicing, the frequency of the pollard regime depends on the tree species and the use the regrowth will be put to. Palatable species like elm and lime were cropped annually or biannually as a source of winter fodder, and willows were cropped on a similar regime as a source of the flexible withies used in basket-making. Trees used to produce firewood or timber were cropped on a longer cycle, usually about 20 years. Regrowth from a pollard tends to grow out from the trunk in a gentle curve rather than growing straight like coppice regrowth. In the case of beech, this was exploited to produce the curved timbers needed to make the gable ends of medieval cottages and the 'ribs' of wooden ships.

As with coppice, pollarding greatly increases a tree's lifespan and most ancient and massive trees in Britain are old pollards. The iconic English oak with a massive trunk and great limbs spreading out ten or 12 feet up is a product of human intervention rather than of nature (both native oak species grow tall and straight if unmanaged). Wood pasture and pollards are very good for wildlife. As the tree ages, the trunk begins to decay and hollow out, creating dead wood that is important to many species of fungi and insects, and the holes and hollows are used by nesting birds and roosting bats.

Woodland in Decline

Ancient woodlands and wood pastures survived and were managed to the benefit of both trees and wildlife because they were an important part of the rural economy. This changed following the Industrial Revolution as the population shifted from the countryside to industrial cities, commoners disappeared, coal replaced wood and charcoal, products that had been made from locally produced wood were replaced by those forged from iron and steel or made from imported timber, and wooden ships were replaced by ironclads and steel merchantmen.

Large-scale destruction of ancient woodland occurred in two main phases:

  • During the agricultural boom between 1840 and 1870, roughly a quarter of ancient woodlands were grubbed up to make way for agriculture.

  • Since 1930 half of ancient woodlands have been lost to agriculture, forestry and development.

Ironically, during this period the total amount of woodland cover in the UK has increased to more than 12%; however, only 40% of this is semi-natural native woodland of which 12% is ancient woodland, and overall the quality and wildlife value of surviving native woodlands has greatly declined.

The overall increase in tree cover is the result of two factors:

  • The development of secondary woodland on areas of heathland, downland and rough pasture which have fallen into decline as a result of the loss of grazing and other traditional practices. Such unmanaged secondary woodland is of far lower ecological and landscape value than ancient woodland.

  • The introduction of large-scale forestry plantations. These make up almost 60% of UK woodland, and are virtual wildlife deserts.

The decline in the quality of woodlands has come about as the result of neglect and of the introduction of exotic species into the countryside. Most surviving woodland species have adapted to the conditions present in coppice and wood pasture; unmanaged woodlands (which lack the large grazing animals like aurochs found in the Wildwood) can become so dense there is no ground flora or scrub layer. Woodland species depend on native tree species and are unable to exploit introduced species.

In addition to the 42 native species of tree and large shrub that occur in Britain, more than 600 introduced species can be found in the countryside. Some introductions are ancient: English elm (as opposed to the native wych and smooth-leaved elms) is believed to have been brought into the country in the Bronze Age and sweet chestnut was brought over by the Romans, but these early introductions were carefully managed and so posed little threat to more natural woods. Most introduced species need to be nurtured to survive, but a few thrive in the UK and can outcompete and replace native species. These include sweet chestnut and sycamore which come into leaf early and produce heavy shade, suppressing woodland flowers and native tree saplings. Rhododendron ponticum is a particular threat to many woods as it creates continuous dense shade and changes soil chemistry to suppress all other species. An English oak can support up to 400 insect species whereas sweet chestnut supports just 16 and rhododendron just two – one of which was introduced with it and the other feeds readily on other species. Grey squirrels introduced from North America in the early 20th Century have exterminated the native red squirrel from most of England and Wales and are now spreading into Scotland and across Ireland, as well as threatening some woodland bird species, damaging trees and taking tree seeds before they are capable of germinating.

The Future

There has been a growing understanding of the need to actively manage woodland and protect native species in the conservation community although this is often not fully understood by the public. Many semi-natural woodlands are well managed by committed owners and conservationists. Traditional management and removing exotic species, however, are costly and labour-intensive, so many areas remain neglected.

The Forestry Commission, which manages 30% of the UK's woodlands, has historically been responsible for destroying half of the country's heathlands, one quarter of the ancient woodlands and vast areas of moorland and peatland. The Commission has finally begun working with conservationists to develop 'landscape' scale management that allows timber production while accommodating wildlife, landscape features and public access. This will greatly benefit British woodlands.

There are, however, commercial interests that benefit from commercial forestry and who actively promote misconceptions about the intensive systems they use. These are presented as of ecological value, while in reality they are environmentally damaging, far from carbon neutral and of almost no wildlife value. Fortunately, government plans to privatise the Forestry Commission lands have been averted.

The failure of successive governments to adequately regulate the importation of plants poses a serious threat to many species as invasive exotic species and pathogens such as the fungus that is currently devastating ash trees enter the country.

By far the greatest threat to the UK's semi-natural woodlands is climate change. This may well create conditions that favour exotics over native species. There are indications that some species such as horse chestnut and holm oak are becoming more prevalent in woodland. The current IPCC prediction of a 6°C temperature increase is of great concern. Even a 4° rise will restrict birch to the highlands of Scotland and the southern limit for English oak will be Yorkshire, although beech and lime will fare better. Unlike the last period of major climate change at the end of the last Ice Age, woodland habitats will not be able to migrate north across the Channel and many species are trapped on habitat islands surrounded by agriculture and development, and will disappear as the climate changes. Conservationists may be faced with the loss of wildlife-rich woodland in southern Britain; it may be necessary to import whole habitats from southern Europe, perhaps replacing English oak with bio-diverse Iberian cork oak woodland.

It is a sobering thought that future generations may not be able to enjoy Britain's iconic ancient woodlands and that we could lose species that are as much a part of our history and heritage as Stonehenge or the Tower of London.

...it belongs to you all and to every landless man, woman and child in England
– Octavia Hill (founder of the National Trust)

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1Because much of the world's water was locked up in the polar ice caps.2The area of southeast England between the North Downs and the South Downs.3Shade-tolerant plants which grow beneath the main canopy of a wood or forest.

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