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.