SOME TYPES OF WOODLAND
Highland Zone and Ireland
Despite the immense size of the charcoal store, there was at least as much land under oakwood in Argyll when [the ironworks] ceased operations in 1876 as when they commenced in 1753.
T.C. SMOUT, A.R. MACDONALD & F. WATSON ON THE LORN BLAST FURNACE
This chapter concerns southwest England, Wales and the Welsh Border, the Pennines and North York Moors, and southern Scotland (see Fig. 1). This region corresponds roughly to that of Palæozoic rocks and closely to the Oak–Hazel Province in prehistory (see Fig. 31). Many woods adjoin moorland as well as farmland. I also include most surviving Irish woods; little survives of the prevalence of elm in wildwood times.
Woods are somewhat less uniquely different from each other than in the Lowland Zone. However, as the National Vegetation Classification showed, there is more variation if bryophytes and lichens are taken into account as well as flowering plants. The latter might display more diversity if they had not been browsed into extinction by sheep, as is shown by the oakwoods of Cornwall, which have escaped that fate.
The effects of tree-planting are widespread and sometimes difficult to detect. Anyone who travels through mid-Wales knows how seldom woods there lack conifers, even though no conifer (except yew) is indigenous.
HIGHLAND-ZONE OAKWOODS
Ancient oakwoods are by far the commonest type from Cornwall to Argyll and from Yorkshire to Killarney (Figs 117–120). They share some characteristics of their Lowland outliers: acid, leached soils with mor humus; prevalent Quercus petræa rather than robur; scarcity of other trees; and calcifuge ground vegetation, with bracken and Deschampsia flexuosa. Often they are on rocky slopes and screes.
Most of these woods have ancient coppice stools, though stool bases may be lower and less conspicuous than in Lowland oakwoods. Many, however, contain timber trees only – perhaps with a few stools in inaccessible places. Often this results from oak-replacement planting.
The woods around Sheffield have been investigated by Mel Jones (1998). Originally there were extensive wood-pastures, encoppiced in the later Middle Ages and used to supply the edge-tool and nail-making industries of Sheffield with charcoal. This use in turn declined in the nineteenth century, when most of the woods were replanted or at least oak-replaced.
An ancient oakwood: Mugdock Wood
Twelve miles (19 kilometres) northwest of Glasgow is a wood to which I was introduced by James Dickson, Scottish ecological historian. It is defined by banks and massive walls, though the wood now spreads well beyond its former limits. The geology is boulder-clay overlying basalt; the soils are strongly acid.
The wood is of oak and birch, with cherry, hazel and many others. Along a stream are ash and a few elms. The oaks are a mixture of the two species and hybrids; few are coppiced, but there are stools up to 8 feet (2½ metres) in diameter. Nearly all the alder and some ash consist of coppice stools. The wood is varied in structure; there are extensive bracken glades, now partly infilled with oak and birch. In shaded areas there are wood-sage and Deschampsia flexuosa; the generally grassy appearance may be due to roe deer.
A pollen diagram from a nearby moor shows birch as the dominant tree since Mesolithic times, with some hazel, alder and oak, but only traces of pine.1 The area contains abundant prehistoric antiquities and is traversed by the Roman Antonine Wall. The place-name Mugdock is Welsh (Maesiddwg). The wood is documented back to the time of King Alexander III in the thirteenth century; it appears on Roy’s military map of c.1755. In the eighteenth century it was regarded as an oak coppice.2
This wood (like others around Glasgow) seems to have been a permanent coppice with fixed boundaries, on the English model. Internally it has been unstable, with periods of neglect and recovery and of shifts between oak and birch. Other mountain woods are like this, for example, around Strata Florida in mid-Wales. An unexpected recent change is the increase in ash, growing from seed despite the deer. The next generation of trees is likely to make this an acid ashwood.
Oak replacement: Inchcailloch
The ‘bonnie, bonnie banks o’ Loch Lomond’ are lined with steep, ancient oakwoods. These have a history as coppices supplying bark (p.225f), small timber for boat-building, and wood for that romantic enterprise, a pyroligneous acid factory (a kind of wood-burning gasworks).3 (Does its ghost yet haunt chemistry textbooks, as it did in my schooldays?)fn1
Professor Dickson introduced me to some of the odd and mysterious islands, and asked my opinion on Inchcailloch, which had been declared a National Nature Reserve in 1962 for its oakwoods.
Inchcailloch (about 150 acres/60 ha), called ‘Old Woman’s Island’ or ‘Nuns’ Island’ after a convent founded in the eighth century, is said to have been a deer-park of King Robert the Bruce. It has a record as a coppice-wood from the seventeenth century down to 1845, involving sales to tanneries and ironworks. A fifteenth-century record, however, refers to timber. Although rocky, it also has a farming history and a church, and is supposed to have been ‘re-afforested with oak in the 1770s’.4
Oakwood now covers almost the whole island, including the ridge-and-furrow of former fields, but the oaks are not those of an ancient coppice. Nine oaks out of ten are timber trees, evenly and rather closely spaced, uniform and apparently a hybrid between the two native species; they lack the gnarled bases of oaks promoted from former coppice stools. They are evidently a plantation of c.1890. Some, uprooted in the hurricane of 1968, are still flourishing.
But this is not the whole story. Here and there, great oaks of markedly spreading habit had evidently been big, widely spaced trees before the planted oaks enveloped them. There are remains of a previous plantation of pines from the 1820s and 1840s. By careful search we found about 150 oak coppice stools, a few of them 6 feet (2 metres) in diameter, on cliffs and ridgetops or on the shore. There are also ash and alder stools in inland fens and on the less steep shores.
Inchcailloch has little of the infrastructure of an ancient oakwood. It has been replanted twice (three times if the 1770 story is to be believed). Before then it may have been less oak-dominated than it is now. The native trees were exterminated and replaced, but not completely: some stools were overlooked in out-of-the-way places, and a few maiden oaks, perhaps standard trees in the coppice, were spared
Other examples
Around Sheffield there was so much replanting in the late nineteenth century that intact native oakwoods are now few. Yarncliff Wood, Hathersage, lies in a side-valley of the Derbyshire Derwent.5 Most of it is even-aged sessile oak, with a few remaining pines, apparently dating from a replanting in c.1870: the Ordnance Survey map of 1876–80 records coniferous mixed with deciduous tree symbols. The planted oaks are all sessile and somewhat variable, suggesting a local provenance less strongly selected than usual. A few coppice stools survive, especially on unplantable rock outcrops; the oak stools indicate many previous centuries of felling and regrowth. A tract of hazel grows where a flush provides a patch of more fertile soil. Charcoal-hearths and a kiln witness to an industrial history. The plantation ends at a boundary wall, not including the whole of the original wood; outside it oak coppice stools continue, around a quarry where millstones were hewn from Millstone Grit, to the edge of the moor. This moorland edge is not demarcated; a fringe of birch marks a phase of expansion of woodland.
Yarner Wood, a great wood on the edge of Dartmoor, has a most complex history. Outside its ancient woodbank are plantations and natural woods on former fields. The interior is divided between coppice and timber areas. The timber oaks are all sessile, uniform in age and appearance and of good timber quality, probably planted c.1870. Coppice oaks, which include ancient stools, are variable; occasional relict stools lurk among the planted oaks.
Irish timberwoods
Oak coppices were probably not uncommon in Ireland before modern forestry (Fig. 121). Surviving examples include Kilteel Wood, Co. Kildare (embanked like an English wood) and fragments on steep slopes in Co. Waterford.
The Civil Survey of the 1650s often specifies ‘Timberwoods’, a category that would have been unfamiliar to English surveyors. These, presumably, yielded the high-quality timber implied by the Irish barrel-stave industry of the seventeenth century. Some Irish oakwoods today lack coppice stools and yet do not have the uniformity of planted oak. Portlaw Wood, Co. Waterford, probably a surviving part of the Great Wood of Kilconish, has remains of a variable stand of big timber trees, all Quercus petræa and having the variability of wild-type oaks (Fig. 122). Another, containing old oaks, is the old wood of Charleville (Co. Offaly), on an island in a bog. The origin, dynamics and functioning of such woods need investigating.
Oak replacement, widespread in Ireland, may account for the notion that Ireland had little history of coppicing. At Glen of the Downs (Co. Wicklow) a well-constructed earth road separates coppiced sessile oak, with stools up to 7 feet (2 metres) in diameter, from a uniform stand of maiden trees, also sessile, apparently of c.1840. In Tomies Wood, Killarney, most of the oaks are attributed to a planting of 1805 (my ring-counts make them a little later). Although widely spaced for a plantation, they are uniform in size and appearance, and appear not to be pure sessile oak as would be expected in southwest Ireland. Between them grow small pollard hollies. One rectangular compartment of the wood escaped planting and remains as regular oak coppice. Most of the oaks in Derrycunihy, another Killarney oakwood, appear to be of similar origin, although a few coppice stools survive. A pollen diagram from within the wood shows that it had a long history of roughly equal quantities of oak and birch. The replacement of birch by more oak is clearly shown in the uppermost layer of the deposit: ‘at no time in the last 5,000 years has Quercus had such a dominance in Derrycunihy Wood’.6
Other trees in oakwoods
Many oakwoods now contain little but oak, sometimes with patches of hazel or alder. The commonest associated trees are birch and rowan, or holly in Cornwall and Ireland.
Many oakwoods were once more mingled with other trees. Where oak was wanted for bark, other species might be extirpated. In Scotland these were called ‘barren timber’ and might be felled at any time of year, whereas oak was sometimes restricted to early summer when the bark would peel.7 How energetically or effectively extirpation was applied would have varied from place to place: it has had no lasting effect on Mugdock Wood. At least as important may have been browsing, which would favour oak as relatively unpalatable and more likely to recover from damage.
Ground vegetation
Highland-Zone oakwoods can develop specifically woodland vegetation, including buried-seed coppicing plants, like Lowland woods. This is best seen in woods among farmland, as in Cornwall or middle Monmouthshire. Many woods, especially if they adjoin moorland, have three other types of ground vegetation. The flora may be nothing but grasses or bracken, the wood being little more than grassland with trees. Or it may be reduced to heather, the wood being moorland with trees. Or there may be a rich bryophyte flora, as in many woods of the far west of Scotland and Ireland.
The National Vegetation Classification is at its best when dealing with oak–birchwoods, recognising nine subcommunities, distinguished mainly by their ground vegetation (including ferns), with some contribution from ground bryophytes.
Livestock have been let into woods, either deliberately or by not maintaining the boundary fences or walls. In Scotland this was a regular practice, to the extent that a landowner wanting to fence a wood after felling it was obliged to compensate tenants for the pasture lost. Woods were used especially, but not exclusively, by cattle and in winter; having woodland dispensed farmers from keeping beasts indoors and giving them hay and straw. Woodland was valued as shelter, but the pasture was worth having. What was that pasture?8
Some grasses, such as Anthoxanthum odoratum, tolerate shade but are tenuous and of little nutritional value. Other woodland plants are distasteful, or poisonous, or die down in winter, although brambles and dead leaves might serve as iron rations. Most bryophytes are not eaten. Holly might be pollarded for animals to browse, as in the famous hollins of the Stiperstones (Shropshire) and in the Pennines and possibly Killarney, although Smout has few examples from Scotland. However, when Sir John Sinclair referred to ‘the fine strong grass with which the woods abounded’9 this must mean that the woods were sparse enough to have real grassland between, not just under, the trees: they were not really woodland, but tree’d grassland. (According to Monteath’s Forester’s Guide (1814), an oakwood ought to have stools only 8 feet (2½ metres) apart, which would have precluded any pasturage; but this was a counsel of perfection, seldom achieved.)
This history doubtless explains why many Highland-Zone woods are poor in woodland flowering plants. Browsing would have subtracted most of the characteristic woodland plants, eaten when they emerged in the hungry season of late winter and early spring. It might have prevented a ‘normal’ woodland flora, with buried-seed plants and others adapted to coppicing, from ever arising.
HAZEL-WOODS AND HAZEL–ASHWOODS
Hazel-woods survive less often than oakwoods, probably because hazel grew on more fertile soils and was grubbed out to make farmland. Many an oakwood has patches of hazel within it, often on less infertile soils (marked, for example, by bluebell instead of bracken).
The extent of Highland-Zone hazel-woods, however, is probably under recorded. More extensive hazel-woods can survive; I have seen one in lowland Aberdeenshire. The most remarkable are on the west coast and islands, woods in an extreme Atlantic climate (a temperate rainforest) with many special lichens, including at least one known from nowhere else in the world. They are supposed not to have been coppiced, although this seems hardly likely in an area with little woodland, and Smout gives a record of hazel ‘cabers’ for roofing.10
Hazel–ashwoods are frequent on limestone, as in South Wales. Peterken recognises three Highland types, and the NVC adds a fourth. A famous example is Rassall Ashwood on Loch Kishorn.
An Atlantic hazel-wood
The Burren, that famous limestone plateau in west Ireland, is an outlier of the dry, sunny, flowery garrigues of the Mediterranean; it may have been less distinctive in the past when it had more soil (since vanished into the underworld of karst caverns). It has long been noted for its hazel ‘scrub’. The Civil Survey of the 1650s has many entries of ‘rockie dwarf wood’.
At the base of Slieve Carran, beneath the towering east-facing cliff of Eagle’s Rock, is a dense hazel-wood.fn2 It is a nameless but sacred wood, for here (the Ordnance Survey avers) are the ruins of St Mac Duagh’s Church, his Bed, the Grave of his Servant, and his Penitential Stations. A cluster of tiny fields could have been where the hermit grew his beans and cabbages, as holy men still do on Mount Athos.
Physically, too, it is an extreme of what woodland can do, a place not quite of this world. The wood is almost all hazel, with stools up to 6 feet (2 metres) in diameter. There are occasional ashes, all of them huge stools 5 to 8 feet (1½ to 2½ metres) across (Figs 123, 124). These establish that it is an ancient coppice-wood, last cut probably more than a century ago. Unusually, ash shows no sign of taking over the wood.
The ground is rounded limestone boulders, evidently a Pleistocene scree that has been so long without moving that the sharp edges have been dissolved away by karst action. Pleurocarpous mosses and liverworts form a thick ground layer and hide treacherous gaps between boulders; they form bulging masses on hazel stems, as in cloud-forests on tropical mountains. Everything not moss-covered is lichen-covered. Ferns and sparse flowering plants struggle through the bryophytes; one of the commonest is helleborine (Epipactis helleborine).
The wood is not specifically mentioned in the Civil Survey. The Ordnance Survey of 1840 and its successors down to 1913 show it only as scree. However, the ash and hazel stools leave no doubt that at least the upper part is ancient woodland. It was visited by the British Vegetation Committee in 1908; it was then 15 to 20 feet (4½ to 6 metres) high and contained much the same plants as it does now. Sir Arthur Tansley, who took a dim view of ‘scrub’, admitted that it could have ‘a perfectly good woodland flora, though not numerous in species’.11
The wood has probably extended downhill in the twentieth century. Wind-stunted, goat-bitten hazels are scattered in the fissures of the adjacent karst plateau. The wood itself shows little sign of browsing except on hawthorn. In the past it may have had a functional wall separating it from the pasture.
An Irish mixed hazel-wood: St John’s Wood
This is a huge wood (for Ireland) of 200 acres (81 ha) on flattish ground between a bog and Lough Ree. The free edges are bounded by a massive wall. The wood is a coppice, last felled c.1920; a small area was cut c.1990. It is remarkable for its rich flora; it has almost all the possible Irish trees and shrubs except Arbutus.
There are two distinct types of woodland. Most of it is dominated by hazel stools, with occasional ash, wych-elm, crab, bird-cherry and cherry, and a scatter of small timber oaks and oak stumps. Ash and hazel form big stools. Ash is on the increase. The oaks are mostly robur, rare as a native in Ireland. Soils are chiefly mull, possibly overlying karst limestone. The ground is covered in ivy, primrose and bryophytes (but not dog’s-mercury, uncommon in Ireland). Here, too, the hazels are mantled in bryophytes. At the bog and lough edges the wood is fringed by spindle, blackthorn and other shrubs.
Here and there are patches of coppiced oakwood, mingled with holly, hazel, birch and occasionally Sorbus hibernica (the only tree endemic to Ireland). These have mor humus and are carpeted with Luzula sylvatica, the common ground vegetation of ungrazed oakwoods. The oak stools are up to 12 feet (3.6 metres) across.
As a varied mixed coppice, probably of monastic antecedents, this is the Irish equivalent to the Bradfield Woods. It is one of the very few surviving descendants of the Hazel–Elm Province of wildwood times, predominantly calcareous and even retaining a few wych-elm stools.
OTHER WOODLAND TYPES
Alder-wood
Alder occurs on flushed sites within Highland, as in Lowland, woods. It is especially common in South Wales, where gwern, ‘alders’, is one of the commonest tree place-names. Its unpalatability to sheep would favour it. Peterken has four types of Highland alder-wood, one characterised by bird-cherry.
Outliers of elm-, lime- and beechwoods
As outliers of oakwood occur in infertile parts of the Lowland Zone, so do outliers of Lowland woodland types in the more fertile parts of Highland woods.
Small patches of elm occur throughout Wales, Scotland and Highland England, often as groups of huge wych-elm stools within other types of woodland. Elm, very palatable, has probably lost ground to browsing; it tends to survive on cliffs or in woods among farmland. Peterken recognises three Highland-Zone variants of ash–wych-elm wood.
Swaledale (Yorkshire), with its extensive limestone, is one of the largest areas of the British Isles with no oak. In historic times elm was one of the commonest trees; it survives as great stools (along with yew, also susceptible to browsing) high on cliffs.
Patches of lime occur in Devon, South and mid-Wales and the Lake District, up to the limits that the tree reached in wildwood times. Often they are in ravines or on rocky ground, although the connection is weaker than with elm.
Ancient beechwoods extend into the Forest of Dean, Wye Gorge and southeast corner of Wales, on both limestone and acidic rocks and on wood-pasture and woodland sites. They reach high altitudes on Mount Blorenge between Abergavenny and Blaenavon. Blaenavon Beeches include a coppice-wood at 1,100 feet (335 metres), which nevertheless produces seedlings. The Punchbowl is a tract of surrealistic beech pollards at a similar elevation, affected by avalanches that roar down from the mountain above. This is one of the nearest approximations in Britain to a natural tree line, as with the tree-limit beeches in the outer French Alps and in the Balkans.
The Highland-Zone catena
In many places, in the mountains of Britain and in the glens of the south of Ireland, a wood occupies a steep valley-side of some relatively infertile rock. Typically the upper and middle slope is oakwood (or oak–holly), with hazel on the footslope, a narrow fringe of elm at the bottom, and alder lining the stream. I interpret this as sequence due to a catena of soil development: thousands of years of rain have washed out minerals from the upper and middle slope, to accumulate at the base where the more demanding trees take advantage of them.
Footnotes
fn1 In Japan I met a man who made pyroligneous acid as an ‘organic’ pesticide.
fn2 I am indebted to Dr Sasha van der Sleesen for introducing me to this wood. It is a breakneck place and should not be visited too much because of damage to bryophytes.