Scotland’s woodlands

Our native woodlands are one of the most characteristic elements of the Scottish landscape. From rocky shores of our varied coastline to the high mountains, Scotland has an exciting range of different woodland types. Each has its own unique and special magic. These woods are defined by the richness and diversity of our geology, soils, climate and topography.

The woods that clothe the hills and glens of Scotland have been shaped over the millennia by people working with nature and are home to many fascinating and beautiful species. From the ancient mighty oaks in our historic parklands to the gnarled and twisted dwarf trees high up at the treeline, Scotland has an incredible diversity of woodlands waiting to be explored.

Oakwoods

Upland oakwoods

Amongst Scotland’s best-kept secrets are our rainforests! Under the influence of the mild, wet Atlantic climate in the west of the country, these woods have developed luxurious carpets of ferns and mosses, and a unique range of associated species. The main tree species are oak (most commonly sessile, but locally pedunculate) and birch, with varying amounts of holly, rowan and hazel. The amount of oak tends to decrease in the north-west and higher up the hill, and the woods become more dominated by birch. Some of these woods have a very rich ground flora in the spring, with bluebells, primroses, violets, bugle, wild garlic, stitchwort and many species of fern. As soils become more acid, grasses and bracken become more common and, on very acid soils, blaeberry and mosses dominate.

Amongst the most important features of these woodlands are the lower plant communities – mosses, liverworts (together, these are called bryophytes), and lichens. There are several hundred species of bryophytes and lichens in the Atlantic oakwoods; many tiny, with amazing and beautiful structures when seen under a hand lens, others large and hanging down from the trees like hair or peeling wall-paper. The climate of the west of Scotland is ideal for these species, which need a humid atmosphere, and thrive in an abundance found nowhere else in Europe – and in few parts of the world. In fact, these woods, are one of the most uniquely Scottish of all our habitats.

Western oakwoods also support characteristic fauna – their distinctive breeding bird assemblage includes redstarts, wood warblers, and pied flycatcher. During the early morning in late spring and early summer, male redstarts can be heard – and if you are lucky seen – defending their territories with song, from the very tops of the oak trees.

Several rare species of butterfly also make their homes in some of the woods. Chequered skippers are very rare in Britain, found only in open woodland in the west of Scotland, where they lay their eggs on purple moor grass. Pearl-bordered fritillaries live in similar areas but choose violets to lay their eggs on.

These woods have historically supported people as well, and not just for their timber. In the 18th and 19th century, many of them were coppiced; their wood was used to make charcoal for iron smelting and gunpowder, and their bark was used for tanning leather. These industries finally ceased over 100 years ago, since when the woods have grown up and developed into mature stands.

Upland oakwoods are a priority habitat in the Scottish Biodiversity Strategy and are also protected under the European Habitats Directive  . Discover the magic for yourself – some of the best oakwoods in Scotland are on National Nature Reserves.

 Taynish is one of the largest ancient oakwoods in Britain. It lies on a scenic peninsula overlooking Loch Sween and has an atmosphere all of its own. The woodland’s dripping ferns and mosses mingle with marshland and grassland to support over 300 plant species and more than 20 kinds of butterfly.

Loch Lomond  in the heart of Scotland, famous for its beautiful wooded shores and islands. The reserve embraces five of the loch’s islands, each supporting rich, mature oak woodland. Bluebells and wild garlic carpet the woodlands in spring when migrant warblers, flycatchers and redstarts start to return.

Glen Nant its slopes cloaked in a rich mixed woodland. Many trees were felled from 1753-1880 to supply charcoal to the nearby Bonawe Iron Furnace (now managed by Historic Scotland and open to the public). Stems have regrown from the cut stumps and now carry a lush growth of mosses and lichens.

Glasdrum, a wild woodland which climbs from the seashore near the head of Loch Creran up the slopes of Ben Churalain. The changes in altitude and the presence of both acid and lime-rich rocks make for a rich variety of trees, plants and insects. The reserve is also notable for a range of butterfly species, including the rare chequered skipper.

Glencripesdale, beautiful and remote. It’s a long way in to this remote woodland on the shores of wild Loch Sunart, but you’re rewarded with stunning views and you may even see otters. The damp, shady conditions of the broadleaf woodland are ideal for a lush growth of ferns, mosses, liverworts and lichens.

Ariundle’s trees are covered in a lush growth of mosses, ferns, liverworts and lichens, which thrive in this damp climate. The woodland is also home to a wide variety of birds.

Loch a’ Mhuilinn is the most northerly oakwood in Scotland. The stunting effects of westerly gales are clearly visible with some of the oaks reduced to a creeping form near the sea.

Caledonian pinewoods

Our only native coniferous forests, and a link to the vast boreal forests which encircle the globe, the Caledonian pinewoods occur on thin, infertile, mineral soils. Many of those in the cold, dry, east are almost completely dominated by Scots pine, whilst woods in the milder, more humid west often have much more diverse canopies with birch, rowan, alder, willow, holly and hazel.

The ancient, wide-crowned ‘Granny’ pine, standing majestically above the heather moorland, is an iconic feature of the Scottish landscape. Unfortunately, these are a sign of centuries of decline in the native pinewood, and may be the last remnants of an area where – due to burning and grazing – trees have not been able to regenerate for hundreds of years. Fortunately in many areas, a reduction in deer numbers is now allowing these trees to germinate and pinewoods are spreading again, especially in parts of Strathspey.

Compared with some more fertile woodland types, they do not have a large diversity of plants and animals, but they do support characteristic species which occur nowhere else. Birds such as capercaillie, black grouse and Britain’s only endemic species of bird, the Scottish crossbill, can be found in these woods. Less obvious, but equally fascinating species of pinewoods include the wood hedgehog and other tooth fungi  – a curious group which have teeth instead of gills on the underside of their caps. The wood hedgehog  is good to eat, but many of the other species are either too tough or bitter to eat – and some are so rare that they are protected. The ground flora is often dominated by acid tolerant plants like bell heather, bilberry and crowberry, amongst which grow more delicate flowers such as lesser twayblade, creeping ladies tresses, intermediate and one-flowered wintergreen, and twinflower. 

Old or dead trees and rotting wood support many rare insects including the specialist hoverfly Callicera rufa, which lays its eggs in rot holes in old pine trees.

Native pine woodlands are a priority habitat in the Scottish Biodiversity strategy and in the European Habitats Directive.

Some of the best areas of native pinewood are protected on National Nature Reserves, where you are welcome to visit at any time.

Loch Fleet: the pines of Balblair Wood were planted after a severe storm flattened a previous pinewood in 1905. Despite their recent origin, they support healthy populations of three particularly attractive flowering plants characteristic of pinewoods, creeping lady’s-tresses, twinflower and one-flowered wintergreen, which are a living link to the great northern forests that girdle the planet.

Loch Maree Islands: three large islands and about 40 small ones make up this reserve. They support one of the most ancient and least disturbed fragments of native pinewood left in Scotland, with an unusual patchwork of well-grown juniper scattered throughout.

Beinn Eighe, Britain’s first National Nature Reserve, features wonderful mountain scenery and ancient pinewood fragments overlooking Loch Maree. The reserve is home to typical Highland wildlife, including red deer, golden eagle and the elusive pine marten. The woodland is rich in moisture-loving mosses and liverworts, and the bogs support an outstanding variety of dragonflies.

Glen Affric, often described as the most beautiful glen in Scotland, has one of our largest remaining ancient pinewoods. Capercaillie, black grouse, crested tit, crossbill, golden eagle, red-throated diver, pine marten and otter are all present. The reserve is also a great place for hillwalking, mountain biking on forest tracks, and open water canoeing.

Cairngorms National Nature Reserves:

Abernethy is the largest native Scots pinewood in Britain. It has a unique mix of woodland and northern bog, with a great variety of homes for breeding birds such as capercaillie, crossbill, crested tit, osprey and goldeneye. Abernethy is also well-known for its many rare northern insects.

Glen Tanar is another large and fine pinewood, supporting typical pinewood plants and animals, including Scottish crossbill, capercaillie and red squirrel, blaeberry and twinflower.

Invereshie and Inshriach, on the edge of the Cairngorm plateau, where twisted and gnarled pines mark the passage from peaceful pinewood to exposed mountain. Red squirrel, pine marten, crested tit and crossbill all make their homes in this expanding woodland.

Glenmore is a haven for wildlife and outdoor enthusiasts alike, where woodland specialists like red squirrels, crossbills and crested tit can all be found and the forest is often alive with the sound of bird song.

Birchwoods

Scotland’s birchwoods are by far our most widespread and extensive woodland type, covering large swathes of the uplands on the more acid, infertile soils. Three birch species are indigenous to Britain: Silver birch, Downy birch and Dwarf birch. Dwarf birch does not grow taller than a low shrub and the habitat where it occurs is described elsewhere on this site under minor woodland types. In the cool, wet and windy climate of the northwest Highlands, downy birch is the dominant species, forming woodland whose canopy rarely exceeds 10m; whereas in the cool boreal climate of the east and central Highlands, the delicate silver birch prevails.

Birches are pioneer trees which can rapidly colonise disturbed ground to form even-aged woods. As young birches regenerate onto adjacent, previously un-wooded areas, often in response to management influences such as fire and changes in grazing pressure, so birchwoods sometimes appear to “move” across the landscape, while the “parent” woodland matures and grows old. The mobility of upland birchwoods has shaped their wildlife, and has important implications for future management.

On the poorer soils there are few woody associates other than rowan, occasional holly and sessile oak, and locally, Scots pine. However, on more fertile sites any of rowan, ash, aspen, alder, goat willow, gean, bird cherry, juniper, hazel, hawthorn and blackthorn may be found. Juniper sometimes forms an understory in birchwoods of the eastern Highlands, while aspen frequently occurs within upland birchwoods where mineral soil is present as small groups and rarely as extensive stands. 

On all but the most acidic sites, birch “improves” the soil to allow development of a grass-herb flora on sites previously dominated by dwarf shrub heath. Although very few plant species are confined entirely to birchwoods, they favour the growth of herbs and grasses which are less common outside woods, and they support a very rich bryophyte flora, including many rarities in western woods. Some northern plants like chickweed wintergreen and globe flower (in ungrazed woods) are strongly associated with Highland birchwoods.

Birchwoods provide valuable habitat for woodland birds such as wood warbler, redstart and black grouse. The wood itself rots quickly and provides valuable deadwood habitat for fungi, beetles and hole-nesting birds.

Birchwoods are important habitats for a number of notable species (including the UKBAP priority species juniper, pearl bordered fritillary butterfly, and the aspen hoverfly.)

Upland birchwoods are a priority habitat in the Scottish Biodiversity Strategy Upland birchwoods HAP.

You can visit some lovely examples of this woodland type on our National Nature Reserves:

Craigellachie 

Only a few minutes walk from the village of Aviemore, on the slopes above the main Perth to Inverness road, sits the imposing birch wood of Craigellachie. It is a peaceful place where you can enjoy a walk at any time of the year.

Muir of Dinnet 

This National Nature Reserve in Grampian is a beautiful mosaic of wetlands, birch woodland and moorland with some interesting archaeology.

Wet woods

This woodland type is widespread across Scotland, associated with wetlands, rivers and lochs. Alder, birch and willow are usually the main tree species present, but many other trees and plants can be found. As these woods can be hard to get into, they are often un-managed and probably represent some of our most “natural” native woods, with a really “wild” feel to them. Wet woodland occurs on poorly drained or seasonally wet ground on a range of soil types from nutrient-rich mineral to acid, nutrient-poor organic soils. By their nature, they occur mainly as small woods or localised patches in larger woods on floodplains, as successional habitat on fens, mires and bogs, along streams and hill-side flushes, and in peaty hollows. As wet woodland combines elements of many other ecosystems, it is an important habitat for many taxa. The high humidity favours bryophyte growth, and a large number of invertebrates are associated with its constituent tree species, alder, birch and willows. Dead wood within this woodland type can be frequent, and its association with water provides specialised habitats not found in dry woodland types – the fly Lipsothrix nigristigma for example is associated with log jams in streams. Wet woodland also often provides cover and breeding sites for otters.

Wet woodland  is a priority habitat in the Scottish Biodiversity Strategy, and two particular types are also protected under the European Habitats Directive: alluvial alderwoods and bog woodland  .

Visit Whitlaw Mosses NNR: four wetland jewels tucked into the troughs of the Selkirk landscape. Each site has its own unique feel, ranging from lichen rich willow scrub to open moss carpets, feathery sedge swamps to sweet smelling herb meadows and butterfly favoured grasslands.

Gordon Moss is a Scottish Wildlife Trust reserve in the Scottish Borders which is a remnant of a large floodplain mire. The site is dominated by wet, birch-willow floodplain woodland over a range of peatland habitats – rich fen, poor fen, acid bog and fen carr. A wide range of invertebrates and orchid species occurs.

Explore the extensive wet woodland and fen at the Endrick Mouth and Islands (Loch Lomond NNR) – NB. a good way to see the wood is from the river!

At the mouth of the River Spey is a completely different kind of wet wood that has developed on shifting river islands; this type of wet woodland is internationally important. The Speyside Way   goes along the river bank and the woodland can be easily appreciated from there.

Ashwoods

These are the woods of our richer soils, often hidden away in dens and gullies, and as such they have a very restricted distribution throughout Scotland. Ashwoods are typically moist and shady, and wherever they occur they form rich assemblages of woodland plants including many rare and colourful species. In the uplands, they can represent real oases of biodiversity with a wide range of associated species in an otherwise barren landscape.

The largest ashwoods occur on limestone, i.e. on well-drained, base-rich soils, but the type is also found on more acid poorly-drained soils where there is flushing of nutrients. Often these latter are just small fragments of woodland with irregular margins or narrow strips along flushes, riparian tracts, outcrops and steep banks. Characteristically, these woods are dominated by ash, but may also feature wych elm, oak and hazel, and alder may be present where the ground is wetter. In the north-west of Scotland ash is often scarce, but the type is represented by some of the most westerly European examples of coastal hazel scrub that is rich in lichens  and higher plants.  

Because of the strong association in distribution between this woodland type and limestone, many ashwoods contain archaeological features that point to people’s long historical involvement with ashwoods such as small quarries, the remains of lime kilns and other relicts of an industrial past. Many of these woods have been treated as coppice in the past, others have been wood-pastures, but most now have a high forest structure.

Most ashwoods are probably ancient, and they are amongst the richest habitats for wildlife in the uplands, notable for bright displays of flowers such as bluebell, primrose, wood cranesbill and wild garlic. Many rare woodland flowers occur in upland ashwoods, such as dark red helleborine and whorled Solomon’s seal. Ashwoods also harbour a rich invertebrate fauna, which may include uncommon or declining species. The alkaline bark of old ash (and elm where it still survives) supports an important lichen flora, particularly the Lobarion community. Amongst the breeding birds are redstart, wood warbler and, in north-west Scotland, redwing.

Upland mixed ashwoods are a priority habitat in the Scottish Biodiversity Strategy and are also protected under European Habitats Directive.

There are some wonderful examples of this woodland type to be visited in our National Nature Reserves such as:

Rassal Ashwood is one of Scotland’s few natural ashwoods and the most northerly in Britain. The underlying limestone creates unusually fertile soils, which support many flowering plants. The woodland was once managed to provide feeding for grazing sheep and cattle, and many trees show signs of historical pollarding or repeated harvesting.

Glasdrum Wood This wild woodland climbs from the seashore near the head of Loch Creran up the slopes of Ben Churalain. The changes in altitude and the presence of both acid and lime-rich rocks make for a rich variety of trees, plants and insects. The reserve is also notable for a range of butterfly species, including the rare chequered skipper.

Clyde Valley Woods This reserve features gorge woodland that’s typical of the Clyde Valley. The steep gorges have protected the rich mix of ash, oak and wych elm trees from felling and grazing. There is a wide variety of bird life, including warblers, flycatchers and redstarts, and in spring, colourful carpets of bluebells and primroses greet you.

Ballachuan Hazel Wood is a Scottish Wildlife Trust reserve in Argyll. The Atlantic hazel woodland cloaks a low ridge overlooking Cuan Sound. It is a site of international importance for its lichen flora, with many species depending on the hazels. The wood has rich ground flora and is a good site for breeding birds and summer migrants.

Wood pasture and parkland

Ancient wood pastures are areas of grazed pasture, heath or open hill with a scattering of iconic open-grown veteran trees. Once a common feature of the Scottish landscape, they provided shelter, pasture and fodder for livestock, as well as wood products for local people. The trees themselves often show signs of earlier working and may have been obviously pollarded (cut back to a high stump out of reach of grazing animals), regenerating with multiple stems to provide poles, or browse for livestock in harsh times; signs of ancient fields or abandoned crofts can often be found nearby. The grazing prevented competition by younger trees, allowing some individual trees to survive to a great age.

Wood pastures are a kind of living ancient monument, where the living things – the veteran trees – are of as much interest as built structures and earthworks which may exist elsewhere, for they are an ancient part of our man-made or cultural landscape that pre-dates the Highland clearances.

This woodland type is widespread throughout upland and lowland Scotland with an estimated extent of between 8000 and 17000 hectares.

Old, open-grown trees are the defining feature of ancient wood pasture. The sunlit canopies attract insects and other wildlife less suited to denser woodland. As the trees reach old age, growth slows until the crowns start to die-back. In a pasture situation, with no competing trees, the period of decline can last for many years – centuries in some cases. Mosses become established on the large branches and in crevices in the bark; wood-rotting fungi colonise broken branches and stems; beetles move into the dry deadwood and sap-sucking flies and hoverflies find a niche in the rot-holes, sap runs and other scars that these veteran trees accumulate. The process of ageing provides an uninterrupted supply of deadwood in various stages of decay, ensuring the needs of species continue to be met. This long-term continuity is critical. Some insects and lichens occur only where there has been a presence of old trees stretching way back in time. The roots of ancient trees also develop complex communities of mycorrhizae, the fungi that play an important role in nutrient uptake by trees. The surrounding pasture and open woodland flowers provide nectar sources for flying insects. Semi-natural pasture will support grassland fungi, rare butterflies and moths. Also, birds, such as woodpeckers, flycatchers and wryneck, as well as bats, stoats and weasels.

To reflect its international importance and vulnerability, its value for a wide range of associated priority species, and its role in representing the historical legacy of past management, wood pasture and parkland has been made the subject of a priority Habitat Action Plan for wood pasture and parkland where a range of measures to protect and enhance this precious and important habitat have been specified.

Visit Rassal Ashwood, a historic wood pasture on a rare outcrop of limestone in Wester Ross. Rassal is one of Scotland’s few natural ashwoods and the most northerly in Britain. The underlying limestone creates unusually fertile soils, which support many flowering plants. The woodland was once managed to provide feeding for grazing sheep and cattle, so many of the veteran trees show signs of pollarding or repeated harvesting.

Breathtaking examples of remarkable ancient parklands can be seen at Dalkeith Estate’s Dalkeith Old Oakwood, and Cadzow Oakwood at South Lanarkshire Council’s Chatelherault Country Park.

Extensive and actively managed ancient upland wood pasture can be visited at the Woodland Trust’s estate at Glen Finglas  .

Atlantic Hazel

What is ‘Atlantic hazel’? It is hazel that occurs in the oceanic climatic areas of the Western British Isles. But, it is more than that, because hazel occurs widely all down the west side of Britain and Ireland, but only in a very few places does it achieve particular characteristics that mark it out as a distinctive habitat of high biodiversity. You know when you step into an Atlantic hazelwood in Argyll, that this is somehow ‘different’; you are struck by the greenness, the lushness, the strangeness of a dwarf wood. This is part of the ‘Celtic rainforest’.

The following pages provide an introduction to this special habitat, the species that depend upon it and how to manage hazel woods for biodiversity. Each page links to a chapter of the SNH publication ‘Atlantic Hazel’, which provide much more information and illustrations. Alternatively, you can download the full publication (but note this is a large file at 21MB).

An Introduction to Atlantic hazel

Note: For more information and illustrations, take a look at chapter 1 of the free Scottish Natural Heritage publication ‘Atlantic Hazel’.

What is ‘Atlantic hazel’? It is hazel which occurs in the oceanic climatic areas of the Western British Isles.

But it is more than that, for hazel is widespread throughout Britain and Ireland, yet it is only in a few places along the western seaboard of the British Isles where the right conditions exist to allow these special Atlantic hazelwoods to develop.

You know when you step into an Atlantic hazelwood in Argyll, that it is somehow ‘different’; you are struck by the greenness, the lushness, the strangeness of a dwarf wood. This is part of the ‘Celtic rainforest’. So many hazel stems confuse the eye. In summer it is dark, shady and sheltered, the only light to filter down to the woodland floor through the dense canopy of hazel leaves is a green light. Mosses abound, forming thick carpets and cushions over rocks and on leaning branches, muffling sound and making it feel damp and cool even when outside, the sun is shining. If it should be one of those ‘typical’ Argyll days with dark clouds and rain, then it can get really dark and wet in an Atlantic hazelwood, and be a haven for midges. You can smell leaf-mould, and the fresh wet greenness of mosses. Ferns are here too, and if you look carefully, dark-hued, leafy-lobed lichens can be seen growing over mosses on branches and rocks.

Atlantic hazelwoods are home to some of the richest assemblages of oceanic mosses, liverworts and lichens found in the whole of Europe.

But Atlantic hazelwoods can also be a light and airy habitat, where the hazel stems are slender and the smooth bark is mottled with pale mosaics: silvery-white, cream, russet, grey and green. These are the small lichens, the crustose species, that form thin, colourful ‘crusts’ over the surface of smooth hazel bark Here, the air passes freely around the stems and bushes. Mosses are mostly low down on the stems, or forming a thin carpet on the ground. When it rains, the rain slides down the stems, over the crustose lichens and soaks into the mossy ‘socks’, and when the rain stops, the stems dry very quickly. It is these crustose lichens that are also some of the real specialities of the Atlantic hazelwoods, and a few occur nowhere else in the world.Atlantic hazelwoods are also home to some fascinating and beautiful fungi, such as Spring hazel cup and the particularly curious hazel gloves. This is a very rare fungus and seems to occur only in Atlantic hazelwoods that are believed to be ‘ancient woodlands’. Surprisingly, very little is known or written about Atlantic hazelwoods, and as a habitat it receives very little attention or even recognition. The Atlantic hazelwoods of western Scotland deserve to be more widely appreciated and recognised as a unique and important habitat in a European and world context.

At the moment very few Atlantic hazelwoods fall within protected areas, so are vulnerable to poor management because they are outwith the focus of current agri-environment schemes and grants for sympathetic and supportive management.

It would be a tragedy to lose Scottish Atlantic hazelwoods through lack of knowledge and misguided management.

Some universally held beliefs about hazel are not true and hard to shake off

• Hazel is an understorey shrub
• Multi-stemmed hazel is all hazel coppice
• Hazel will die out if it is not regularly coppiced
• Hazel will develop into a single-trunked tree if left uncoppiced

None of these statements are true, especially of Atlantic hazel.

Hazel is not ‘naturally’ an understorey shrub, and it grows ‘naturally’ as a multi-stemmed shrub, quite independent of any intervention by man, and certainly without being coppiced.

Hazel will die out where it is gradually left to weaken under increasing shade by tall trees.

Hazel ‘trees’ may develop when hazel is subjected to extended periods of intensive grazing, however, when grazing is removed trees quickly revert back to multi-stemmed shrubs.

There is a real need to stop, look, and think again about hazel, especially the wonderful, ancient and species-rich Atlantic hazelwoods.

The Atlantic hazelwoods are one of Scotland’s most ancient woodlands

Hazel was one of the first woody species to establish along the western edge of Scotland as the ice retreated about 11,000 years ago. This makes Atlantic hazelwoods older by far than the Atlantic oakwoods of Scotland, and even some of the Caledonian pinewoods. 

An unrecognised or misunderstood habitat

Many misunderstandings have arisen about the nature of hazel, mainly influenced from the way that hazel was managed (as coppice) since early medieval times in lowland England. Coppicing has not created hazelwoods, which have existed throughout prehistory, but it has enabled hazel to be commoner in mixtures than it would otherwise be.

The most accepted scenario in woodland ecology, is that hazel is generally referred to as an “understorey” shrub. This is not the case in exposed coastal areas of western Scotland and Ireland.

Hazel is essentially a light-demanding, pioneer species that will invade open ground and form self-perpetuating, pure, dense stands that can persist indefinitely, despite some grazing, and certainly in the absence of coppicing.

Although this habitat has been with us for thousands of years, the Atlantic hazelwoods do not fit comfortably into any of the British National Vegetation Classification (NVC) community types (Rodwell 1991), nor are they recognized in their own right by the European Habitats Directive, the legislation that gives some of the strongest protection to habitats and species.

We now accept that hazel – pure stands of hazel – dominated the landscape of the Atlantic edges of Scotland for many thousands of years, and that presumed relics of this ancient woodland persist today. Coppicing of hazel was probably only ever a very marginal management activity in the oceanic woodlands. The habitat was so widespread that selective cutting of required stems easily satisfied demand. 

Description of Atlantic Hazel

Note: For more information and illustrations, take a look at chapter 2 of the free Scottish Natural Heritage publication ‘Atlantic Hazel’.

Hazel is a multi-stemmed shrub, i.e. there is more than one stem arising from the rootstock in the healthy plant. It is a pioneering, light-demanding shrub, so one of the requirements for successful germination and establishment is that there is no closed canopy above to shade out the emerging seedling. Seedlings germinate from the previous autumn’s nuts. Initially a single stem will arise, soon to be joined by other stems, and in 5-10 years, a characteristic, small, multi-stemmed and branching hazel shrub will develop. Seedlings are palatable to most herbivores, from field voles through to sheep, cattle, ponies or deer. However, once established, and depending on the situation, a typical multi-stemmed hazel stool can reach in excess of 10m in height, although most hazel bushes tend to be between 3-5m high. There are also examples of very exposed, wind-pruned hazel, which forms dwarf stands.

Bark

Young stems of hazel have smooth bark. In Atlantic hazelwoods, this is colonized by a range of crustose lichens (including some species given priority for conservation action under the UK Biodiversity Action Plan), which form pale-coloured, closed mosaics over the surface of the bark.

Old hazel stems (where the bark has become roughened and fissured, trapping moisture) support mosses, liverworts and a profusion of larger leafy lichens such as the tree lungwort  .

Catkins

In the early spring, before the leaves appear, male catkins (“lambs-tails”) develop. The catkins produce conspicuous pale yellow pollen that is wind-dispersed, and dancing hazel catkins are a characteristic sight early in the year, shedding pollen into the spring air.

The female flowers are mostly overlooked because of the showy male catkins; they occur on the same branch as the male catkins, and are small squat reddish buds (“the dwarfy females”). They have neat tufts of twelve crimson styles, which catch pollen.

Leaves and nuts

Hazel leaves are fairly large (up to 10 x 10 cm), oval with serrated edges and a pointed tip. There is a rough feel to the upper side of the leaf (short hairs); the underside is paler with soft, whitish hairs on the veins. Hazel stems bear alternate buds, giving the twig a slightly angular look.

Nuts develop, encased in strong, papery sheaths (bracts, or bracteoles). Young nuts are pale green, changing in colour to ivory and eventually to brown, a strong, wooden nutshell enclosing a single seed (or kernel). Nuts are not produced every year; it depends on several factors, such as the spring weather (incidence of late frosts). Nuts are most often found on well-lit bushes in relatively warm, sheltered situations. Hazel occurring under the canopy of tall trees very rarely flowers or sets seed. Hazelnuts are an important food source for a whole range of animals and birds e.g. in western Scotland field voles, wood mice, great spotted woodpeckers and great tits.

The Celtic rainforest!

Atlantic hazel is part of the Atlantic rainforest. In global terms, coastal temperate rainforest is extremely rare (map), confined to just seven regions in the world: the Pacific Northwest; the Valdivian forests of south-western South America; New Zealand; Tasmania (and a strip along New South Wales of SE Australia); the north-eastern Atlantic (including the Pyrenees, West Highlands of Scotland, Ireland, Norway and Iceland); south-western Japan, and the eastern Black Sea. Total world area of coastal temperate rainforests is estimated to be only 302,227km².

Temperate rainforest experiences high rainfall (with over 1500mm of annual rainfall), but some parts are effectively even wetter through having large number of ‘wet days’ (a day with at least 1mm of precipitation). The regularity of ‘wetting’ throughout the year keeps some areas constantly damp and humid. Added to this can be ‘occult’ precipitation, or sea-mists, which condense as water droplets on coastal vegetation. Temperatures are generally mild and do not vary greatly between summer and winter (equable). North-western Scotland and western Ireland have the most oceanic climate in Europe, and this is why these areas are of international importance for ‘oceanic’ bryophytes, lichens and ferns.

In north-western Scotland, temperate rainforest is estimated to amount to 6,895.8 km² and broadly includes woodlands dominated by oak, birch and hazel, where trees and rocks are often thickly clothed with bryophytes, lichens, ferns and fungi, leading to these woods being termed the ‘Celtic rainforest’.

Scrub or Woodland?

‘Scrub’ used to be a dismissive, derogatory term, often indicating a secondary habitat of low value, but recently, the biodiversity value of scrub has been recognised, resulting in it being reassessed as an important habitat in its own right. ‘Scrub’ is also often taken to be a seral stage, being a transition from open, herbaceous vegetation to woodland.

However, there are exceptions: there are natural types of scrub, but they are very rare. Hazel stands occurring in some parts along the west coast of Scotland and Ireland form climax scrub; this is scrub that has, and will continue to, persist indefinitely under the current climate, and not become infiltrated by taller trees and develop into “woodland”. Hazel-dominated landscapes appear to have persisted in these localities from as long as 10,000 years ago, mostly along the coastal fringes where exposure, thin soils over rocky or steep slopes have inhibited other woody species becoming established.

Hazel ‘scrub’ today usually forms dense, compact stands, the twigs forming a closed canopy, so that within the stand it is relatively sheltered, yet in summer, when in full leaf, it is shaded and dark. Under these conditions, it is almost impossible for other trees to establish.

Can hazel scrub can persist indefinitely?

Hazel possesses a unique advantage over other forms of scrub, such as hawthorn and blackthorn. Hazel stools (being multi-stemmed shrubs) can be constantly replenished, not reliant on the life-span of the single trunk, so the stand can be a structural continuum.

Is hazel a tree or shrub?

The term ‘tree’ has been used for hazel, although strictly speaking it is a ‘shrub’. Hazel ‘trees’ are known to exist, but these are almost always created as a result of the long exposure of the hazel to constant grazing whereby the natural growth form of many stems arising from the rootstock has been thwarted. They are found in upland wood pasture as well as in grazed woodlands.

Hazel dynamics

Note: For more information, explanation and illustrations, take a look at chapter 3 of the free Scottish Natural Heritage publication ‘Atlantic Hazel’.

Old-growth Atlantic hazel, the ‘core’ stands

The ‘special’ crustose lichens of the Graphidion (the ‘script’ lichens), and the foliose (leafy-lobed) lichens of the Lobarion found on Atlantic hazel, are all considered species which require ‘old-growth’ woodland, or long periods of ecological continuity.

These lichens are not present in hazel that has been coppiced. Nor are they present in hazel stands that have recently expanded.

So, how does Atlantic hazel maintain ‘old-growth’ habitat?

A typical hazel stool has a cluster of thin, medium-sized and thick stems. The smooth-barked young stems are colonized by the crustose lichens of the Graphidion. As these stems become older and thicker the bark roughens and crustose lichens give way to bryophytes and foliose lichens of the Lobarion. The ageing stems tend generally to lean outwards, probably from the weight of the canopy they support. This creates a gap in the overall canopy, which enables new young stems to arise and fill the space. Winter storms will damage the canopy, breaking off twigs; abrasion from stems rubbing together in windy weather allows fungal pathogens (such as the Glue fungus Hymenochaete corrugata) to attack and gradually kill off individual stems. This all leads to a considerable turnover of stems within the stool.

New hazel stems (whips) appear to be produced from the base of the stool every year, and this is a critical feature. Initiation of new stem production may be triggered by short periods in the spring when light conditions are favourable. When existing stems are in full leaf, forming a closed canopy, new stems will abort by late summer owing to heavy shade. If a gap persists, however, then new spring whips are able to grow rapidly and fill the space. The annual production of new stems appears to act as a ‘fail-safe’ strategy to ensure the continued viability of the stool.

In the right conditions therefore, each stool is a self-perpetuating ecological unit, always with some young, smooth-barked stems (supporting crustose lichens) and generally some older stems (supporting the foliose lichens). There is an unbroken cycle of replenishment, which is crucial for the ecological continuity required by the more specialized and niche-demanding ‘old-woodland’ lichens.

Hazel stools in different situations behave in slightly different ways

On deep soils in sheltered conditions, the stools tend to be large, well-grown and widely spaced with the canopies of adjacent stools often meeting. In these situations:

• canopy spread can reach 6.5m in diameter, and canopy height can be more than 6 m.
• stools tend to support mostly shade-tolerant ‘old woodland’ lichens of the Lobarion, with the more light-demanding species of the Graphidion only poorly represented.
• there are large numbers of stems per stool, ranging from thin and spindly, to very thick and woody, the latter becoming almost horizontal. The canopy twigs of these collapsing stems gradually adjust to vertical as the main stem assumes a horizontal position. Hence, when the old stems eventually collapse, the canopy twigs are often well above browsing height.
• In some cases, layering of collapsed stems takes place and new stools can be formed, but this is successful only if there is a ‘space’ as competition for light is a prime factor controlling successful hazel establishment.
• Within a closed canopy stand of hazel, the shade created by summer canopies in full leaf is extremely dark, which perhaps partly explains why tree seedlings are unable to establish and are rarely encountered.

On thin soils in exposed situations, stools tend to be closer together, with few thick woody stems.

In these situations:

• the Lobarion is often poorly represented, with the Graphidion dominant on the smooth-barked young stems.
• there is a rigidity within the stand, with a tight, interlaced network of small twigs, which means that internally, the stand is very sheltered, although the outer twigs are often wind-clipped and distorted.
• turnover of stems appears to be far more frequent, with the oldest stems often being no more than 12-15 years old (as a very rough rule of thumb – 1cm girth approximates to one year of growth).

But, despite appearances, stools composed of young stems can be self-perpetuating ‘old woodland’ stands that may have persisted for thousands of years.

Do individual hazel stools eventually die, or do they just get progressively bigger?

Hazel has two strategies for reproduction:

• sexually by wind-pollinated catkins; resulting in the production of seeds encased in hard, woody nuts. Nuts require a mammal or bird to distribute them; but they also float, so can be carried along waterways.
• by cloning, in which new shoots arise from the underground stool; the term ‘self-coppicing’ is sometimes used to describe this mechanism.

How can you age a hazel stool?

How long the stool will live (given ideal conditions), is not known.

In the absence of browsing, basal shoots will be regularly produced from the outer perimeter of the stool. Over time this will lead to an increase in circumference of the hazel stool until, over hundreds of years, it could be enormous. However, no hazel stools are ever encountered with gigantic basal circumference.

Based on casual observations from many Western Scottish hazelwoods over several decades, some observers began to see what they interpreted as ‘hazel rings’ – rather like the fairy rings formed by fungi in old meadows: there would be a series of discrete hazel stools (‘satellite stools’), seemingly arranged around open space. Examples have been seen from Ballachuan and from Mull, where satellite stools were observed around an empty circular space measuring 1.1m to 2.3m in diameter.

The ages of these rings have been estimated at over 1000 years old! More research into this fascinating area is clearly still needed, but the work so far puts a whole new perspective on the way we should perhaps consider the ecological importance of Atlantic hazelwoods, as potentially one of the longest surviving, relict habitats in Scotland.

Diversity

Note: For more information and illustrations, take a look at chapter 4 of the free Scottish Natural Heritage publication ‘Atlantic Hazel’.

The unique climate and long history of hazel woodland cover has resulted in a habitat that is rich in species, many of which are rare or absent elsewhere in Europe.

Lichens

Lichens are probably the most defining species of Atlantic hazel. Their diversity is internationally important, with some species such as the white script-lichen Graphis alboscripta only occurring in Scotland. If you look at the British distribution of many of the species mentioned below (e.g. Yellow specklebelly), you will see that many are mainly, if not entirely, restricted to the west coast of Scotland. This diversity is partly due to the climate and long history of woodland cover along the west coast, but also due to the variation from young smooth bark to old rough bark – each of which supports a different group of lichens.

Young hazel stems have smooth bark, and when they grow rapidly, straight up to reach a gap in the canopy, they are the characteristic “hazel” colour. Some of the earliest colonizers of smooth hazel bark are hardly lichens at all, but small bark fungi that use the chlorophyll in the bark cells of the hazel for their food. Sometimes, these hardly discolour the host bark at all, and it is only the tiny blackish dots and dashes of their fruits that reveals their presence. The species come from groups (genera) of fungi such as Arthothelium (e.g. Arthothelium macounii), Arthopyrenia and Tomasellia.

The next colonisers of young smooth barked stems are small crusty species. These are ‘true’ lichens, in that they are both a fungus and an alga combined, i.e. they have their ‘own’ algae, and do not use the chlorophyll in the bark cells of the hazel for their food. Some have small fruits that are dark or pale dots, and others that are scribble-like lines. It is this last group (the ‘script’ lichens) that lend their name to this group of lichens called the Graphidion. Species include Melaspilea atroides, Thelotrema pectractoides, Pyrenula macrospora  and the rare blackberries in custard Pyrenula hibernica. Have a careful look at any young hazel stem on the west coast and you will see an almost continuous cover of these species! 

Another community of lichens tends to occur on rougher hazel bark of older stems, often with mosses and liverworts. Perhaps the most charismatic and best known lichen of Atlantic hazel is the large leafy-lobed lichen tree lungwort Lobaria pulmonaria. This lichen lends its name to the community of Atlantic, leafy-lobed lichens called the Lobarion. Other distinctive species in this community include yellow specklebelly  Pseudocyphellaria crocata, plum fruited felt lichen Degelia plumbea, octopus suckers Collema fasciculare and frilly-fruited jelly skin Leptogium burgessii.

Mosses and Liverworts

The deep greenness of the mosses and liverworts, clothing rocks, trunks and leaning branches, climbing up the bases of hazel stools, provide the quintessential atmosphere of the ‘Celtic rainforest’. Truly oceanic bryophytes require fairly constant levels of humidity in order to thrive, so generally are found in sheltered habitats and niches, away from bright sun or drying winds, and they are tolerant of low light levels. When entering a hazel stand, you become aware of “mossiness” only when you have penetrated a little distance into the stand, where the closed canopy forms a secure, sheltered and undisturbed habitat, ideal for the development of oceanic bryophytes.

Typically, the Atlantic hazelwoods boast a good diversity of mosses and liverworts with an abundance of the more common western species, but also many very special oceanic species are frequent. Perhaps the commonest moss on hazel in the western Highlands is dwarf neckera Neckera pumila , but other common mosses include the slender mouse-tail moss Isothecium myosuroides var. myosuroides, the common feather-moss Kindbergia praelonga, common striated feather-moss Eurhynnnchium striatum, short-beaked wood-moss Loeskobryum brevirostre and the neat feather-moss Pseudoscleropodium purum. Oceanic (Atlantic) species typically include the frizzled pincushion moss  Ulota phyllantha and the lesser yoke-moss Zygodon conoideus, as well as the liverworts sea scalewort Frullania teneriffae, pointed pouncewort Harpalejeunea molleri, toothed pouncewort Drepanolejeunea hamatifolia, petty featherwort Plagiochila exigua and Killarney featherwort Plagiochila bifaria. More notably, two scarce oceanic species – the balding pincushion moss Ulota calvescens and the liverwort minute pouncewort Cololejeunea minutissima – grow mainly on western hazels.

Fungi

Although there are many fungi that are recorded as growing in association with hazel, there are relatively few that are specific to hazel itself. Hazel is ectomycorrhizal, which means that it grows in a close (symbiotic) relationship with certain fungi: the fungi are intimately associated with the roots of the hazel, and enable the tree to take up nutrients which help to enhance its growth. In return, the fungus receives excess sugars from the hazel, enabling it also to thrive.

Fiery milkcap Lactarius pyrogalus is the most common mycorrhizal hazel associate. When damaged, this species exudes a fiery-tasting milky-substance! Another large toadstool that is recorded with hazel in Scotland is the hazel bolete Leccinum pseudoscabrum, with tubes under the cap rather than gills and flesh that blackens on exposure to air. Mycorrhizal fungi are often sparse in hazel woodland. It has been suggested that soils characteristic of hazel woodland (known as mull humus, due to plant remains being successfully broken down by small creatures in the soil, including plenty of earthworms) support both less species and lower fruit body production than mor soils (mor soils are associated with acidic conditions such as coniferous woodlands or acid moorlands, where cool, wet climatic conditions support fewer soil fauna, so the organic matter is not broken down so quickly).

Sometimes, you can be lucky in hazelwoods and discover some rarely reported fungi. At Morvern, Atlantic bells Chromocyphella muscicola has been recorded, the fruit bodies of which form delicate clusters of bell-shaped cups on the reddish-brown, leafy liverwort Frullania. Another unusual fungus is the striking scarlet elf cup  Sarcocypha austriaca, a distinctive orange-red cup fungus, growing in the spring on fallen twigs and branches in leaf litter.

Winter storms will damage the canopy, breaking off twigs, and abrasion from stems rubbing together in windy weather allows fungal pathogens to get a hold and gradually kill off individual stems. This all leads to a considerable turnover of stems within the stool. The fascinating glue fungus Hymenochaete corrugata has the ability (otherwise found mostly in the tropics), to ‘glue’ together and trap dead, fallen twigs that get lodged against living stems in the hazel stool, so preventing them from falling to the ground. This enables the fungus to feed on the dead wood, avoiding competition from other saprotrophs on the woodland floor.

Although occurring far less frequently, it is thought that the radiating lobes of hazel gloves  Hypocreopsis rhododendri are in some way closely associated with the glue fungus, and may even be parasitic on it. Hazel gloves is a conspicuous species, which somewhat resembles a lichen in that it forms thick, rubbery orange rosettes, reminiscent of minute orange washing-up gloves, with fingers or radiating lobes that clasp around the hazel stems. The species is thought to be an indicator of old growth hazel woodland and its presence puts you firmly in an Atlantic hazelwood habitat.

In western Scottish hazel-dominated woodland, the ground vegetation is varied. The commonest type is a mixture of grasses, flowering plants and bryophytes. In many places, especially on limestone, the ground vegetation is less grassy and more dominated by flowering plants, and these hazelwoods are the extreme north-western representation of the broader ash – rowan – dog’s mercury woodland type, which can develop in exposed situations in the windy far north-west of the British Isles.

Dogs mercury, and bluebell, are both common in these woods in the spring and early summer. Other species which can be found include enchanter’s nightshade, wood sorrel, wood anemone, wood avens, false brome, primrose, and common dog violet. Species such as melancholy thistle and globe flower give a distinctly “northern” feel: Ferns are often present: male fern, lady fern, bracken and hard fern to name but a few. More localised lime-loving ferns which may also be found include regionally unusual plants such as hart’s-tongue and maidenhair spleenwort or, at a higher altitude, the less common green spleenwort.

Atlantic hazel – habitat management

Note: For more detail and advice about the different management options for Atlantic hazel, take a look at chapter 5 (examples) and chapter 6     (advice) of the free Scottish Natural Heritage publication ‘Atlantic Hazel’.

Individual hazelwoods have different histories of management and therefore have different management recommendations. The main hazelwood types are:

• Closed canopy, multi-stemmed stands of pure hazel
• Scattered stools in pasture (a broad, catch-all category)
• Antique, veteran hazel stools
• Hazel in woodlands (including ravines)

Further details of these four types and specific management requirements are given in the above ‘Atlantic Hazel’ chapter downloads. The rest of this page provides a summary of the main management activities that can have a negative and positive impact on Atlantic hazel biodiversity.

Negative management

Coppicing: Disrupts the natural dynamics of hazel stools that are important for biodiversity. All lichens, fungi and bryophytes growing on the hazel and removed with the cut stems will die. Coppicing destroys ecological continuity, resulting in loss of species dependent on this, e.g. mostly lichens of the smooth bark Graphidion community, but also the larger, leafy-lobed lichens of the Lobarion community. Coppicing removes shade and reduces humidity to the detriment of species that rely on these conditions, e.g. Atlantic bryophyte. Fungal diversity is know to be lower in coppiced hazel.

Continuous heavy grazing: Disrupts the natural dynamics of hazel stools that are important for biodiversity. It also leads to loss of habitat structure and ultimately of entire hazel stools. Natural regeneration by producing new shoots from the base of the stool is constantly thwarted by grazing. Hazel stools develop unstable growth forms on few stems, with an unnaturally elevated canopy, prone to wind-blow. Ground flora is trampled and poached while excessive dunging producing nutrient-enriched conditions. Species dependent on continuity of habitat conditions within an old-growth stand may be lost.

Long-term exclosures: Can disrupt natural processes of the habitat by excluding occasional light grazing; this leads to a closing-in of glades and build up of rank vegetation. The gladed edges to hazel stands are compromised and lost to dense, thicket regeneration.

‘Scrub’ clearance: Destroys the habitat.

Unsuitable siting of cattle feeding stations: Causes localized intensive use of areas that results in ground flora being trampled and poached. Excessive dunging produces unnaturally high levels of nutrient-enrichment that is harmful to biodiversity.

Rhododendron ponticum: Invasion by this non-native evergreen shrub results in a general loss of biodiversity through the effects of over-shading, and toxic leachate from leaf-litter.

Positive management

Light seasonal grazing: Light grazing will ensure glades are kept open, an important habitat feature that benefits a range of wildlife within the hazel habitat; there may be some slight damage to stems, and some basal regeneration will be browsed, but the level should be sustainable.

Re-introduction of grazing into hazel stands that were formerly fenced to exclude all grazing: This must be a gradual process, i.e. domestic animals must have access to easy bite as well as struggling through thickets, where animal welfare may be compromised. The aim would be to restore glades within a stand that had closed up into thicket regeneration.

Encourage hazel expansion: Managing grazing to enable isolated hazel stands or widely spaced clumps to form an integrated habitat (without compromising glade or woodland edge habitats), needs to be carefully managed.

Planting hazel to replenish a severely reduced habitat: Using hazelnuts locally sourced, and carefully propagated in a nursery (protected from mice and vole predation), and planted out as well-established saplings, initially protected by Tuley tubes has been successfully carried out, e.g. at Taynish NNR.

Management that will have low impact if guidelines followed

Selective stem cutting: A more ecologically sensitive and sympathetic way of harvesting stems from Atlantic hazel; selective cutting enables the internal integrity of individual stools to be maintained (and their associated biodiversity), and the cohesion of the stand as an ecological unit.

Short periods of intensive grazing: Atlantic hazel has a natural ability to respond to over-grazing for short periods, but extended continuous heavy grazing reduces viability of the stool and the stand.

Short periods of no grazing: A respite period from grazing results in a general thickening-up of the stand, and can be useful to allow recovery from periods when over-grazing may have reduced viability within the stand; however, subsequent reintroduction of grazing at low to moderate levels is recommended to keep glades open.

Assess your local hazelwood

You don’t need to be able to identify the many species that inhabit Atlantic hazel, or be a woodland specialist, to assess the importance of your local hazel woods for biodiversity. We have developed a simple assessment table that leads you through a series of questions to answer whilst in the hazel stand.

Assessment summary

The first stage is to fit your wood into one of four types:

• Closed canopy, multi-stemmed stands of pure hazel
• Scattered stools in pasture
• Veteran stools
• Hazel in woodland (including ravines)

You are then invited to give a brief description of the area e.g.:

“along lower edge of slope, backing on to grazed fields above, and shaded burn below – hazel stands quite open with scattered old bushes; canopy closed in some places, but forming open gladed mosaics. Stools typically with few to about 20 stems per stool, with little evidence of young shoots establishing. Hazel gloves seen on a couple of bushes. Occasional hawthorn present, with willow around burn. Grazed by sheep all year round”.

The next step is to assess the condition of your hazel wood habitat by answering a few questions about e.g.:

• canopy cover
• stool size
• ground flora
• whether the stems are covered with mosses, liverworts and lichens
• grazing evidence
• number of old ‘veteran’ stools

Finally, you are asked to look for some easy to identify indicator species and the general cover of particular groups of species.

Each question is assigned a score, which is then used to assess the relative importance of your hazel wood against a table of threshold scores.

Download the assessment form for more details.

Next steps

The purpose of this exercise is to discover potentially species rich stands of Atlantic hazel, and to encourage sympathetic management, or at least to avoid the worst of unsympathetic management by simply raising awareness.

If you own the woodland and want to improve the management through an SRDP application, either you or your SRDP Case Officer are advised to contact Gordon Gray Stephens, the Atlantic Hazel Action Group (AHAG) project officer for further advice. Gordon will advise whether you need to seek specialist advice to make a simple “dip-in” visit to confirm the results of the Biodiversity Assessment. The results will be taken into account when seeking to put together an application for funding support from SRDP or entry into the Woodland Grazing Toolbox initiative.

Minor woodland types

Urban and Amenity Woodland A tradition of providing open space in urban areas which goes back to the last century has been invigorated in the last decade by the development of community woodlands. These area generally, situated on low value ground in and adjacent to urban centres, and designed for use by a wide range of community interest groups.

Atlantic Hazelwoods Atlantic hazel is restricted to the west coast and often considered a minor woodland type. However, because of the international importance of Atlantic hazel in Scotland, more information can be found on our dedicated Atlantic hazel pages.

Aspen Although aspen is very widespread, occurring across most of Britain, it is reasonably uncommon for it to form extensive stands. In the Highlands, only 21 stands of aspen larger than 1.5 ha are known. Despite this scarcity, these stands are extremely rich in biodiversity, especially lichens and insects. Exploration of aspen in the last few years has discovered several species new to Britain and at least one which was thought to be extinct – and which was last seen in East Norfolk over 150 years ago. Aspen can only spread slowly – it is rarely able to produce seed in Scotland and reproduces by sending out suckers from its roots, which form new trees close to the parents. Over time a large clump of trees can develop, all genetically identical. Interest in aspen is growing rapidly and a conference with published proceedings was held in 2008 to bring together the knowledge which has been developed over the last ten years.

Individual and small groups of trees These are an important part of Scotland’s tree cover and help define the character of many lowland landscapes. Intensively farmed arable areas would appear much more uniform, and support a more limited range of plants and animals without the hedges and hedgerow trees which were established at the time of agricultural improvements.

Montane scrub As tall forest trees, like pine and birch, begin reach their altitudinal limit, smaller species like juniper, dwarf birch and mountain willows become more prevalent and eventually replace them completely. This zone of dwarf trees and low shrubs, which once linked forest and open hillside, and the unique wildlife living in this habitat, have almost vanished from Scotland. At several sites throughout Scotland, people are surveying the mountain woodlands, gathering seed and growing new trees. Schoolchildren are helping by looking after some of these trees through the winter and planting them out onto the mountain the following spring.