The Woodland Heritage

I am lying on the ground, my eyes closed. The dampness of the soft moss blanket I am resting on is slowly creeping through my clothes. I smell wet earth and fresh foliage. A soft breeze creates rustling sounds in the invisible canopy above. At this early hour the sun is still hidden behind the peaks of Mangerton and Torc Mountain and the forests of the Killarney National Park lie in deep shadow. The birds however are early risers these days and the dawn chorus, the spring symphony that will be performed every morning during the month of May, is about to begin. The voices and songs of blackbird, robin, wren and others are slowly building. Single performances turn into duets, other singers join in and soon there is an ensemble of harmonies echoing through the forest. This is the sound of spring, beautiful and uplifting but fleeting. In a few weeks the forest will be a more quiet place, the birds will be busy caring for their offspring, the trees will have fully unfolded their new leaves and the wildflowers on the forest floor will be soaking up the little sunlight that is still filtering through the green baldachin. Primroses and wood anemones will already have done their job for the year and only a few latecomers might still showcase their delicate flowers. Wild garlic and bluebells however will be in their prime, blanketing the field layer of the forest in white and blue. Spring will turn into summer and summer into autumn, a time of year when a different concert is performed in the forest. It is now October in Killarney and yet again I am sitting in the forest in semi darkness. Suddenly the silence is disrupted by a deep bellowing. It’s a sound that seems to come right out of the bones of the earth and in the calm before dawn it echoes eerily from the mountainsides. The call is answered closer to me by an ear shattering roar and I belief to see a dark shadow moving through the trees ahead. The red deer rut has something primeval, it is an event that has been performed in the forests and around the lakes of Killarney every autumn for thousands of years. Every year the deer come down from the mountains into the lowlands. Here the stags round up the does and fight for the right to mate. The bellowing and roaring is often followed by violent head tossing and sometimes the crashing of antlers. Often these fights last only a few minutes and the weaker animal retreats quickly. When two equal opponents meet however the conflict becomes violent and the antlers are being turned into deadly weapons. One late October morning I came across a stag lying in the shelter of a tree, breathing shallow and bleeding from a wound in its flank. On the previous day I had witnessed a lengthy fight nearby and wondered if this was one of the two opponents. Later I learned that the injured stag had died from a punctured lung.

In early November the deer retreat from the valleys and silence returns to the woodlands. It’s the calm of the approaching winter. The dark green tones of summer have been replaced by warm shades of brown and yellow, a last display of colour before the long darkness. The spectacle of autumn however is short lived in these parts. The first storms can come early and strip the trees bare before they had a chance to change into their full autumn gown. Robbed of their foliage the masters of the forest appear in their most stark, almost menacing, fashion. The bare branches of an old oak tree reaching for the grey winter sky is, for me at least, one of the most awe inspiring sights in nature and a symbol of utter resilience.


For the longest time trees have been admired and even worshipped. Their sheer size and longevity makes us look at them in wonderment. Trees provide us with food, building material and fuel and produce vital oxygen. Without trees life as we know it wouldn’t exist. Yet trees are still widely seen as inanimate objects without consciousness and intelligence. In recent years however scientific evidence has confirmed what a small number of naturalists and scientists had suspected all along. Trees as well as other members of the plant kingdom are more than they appear to be. It was discovered that trees not only actively react to changes and threats in their environment, for example by releasing bad tasting chemicals known as tannins into their leaves when someone starts chewing on them, but also warn their nearby companions of the threat. We also learned that trees don’t necessarily fight for resources but rather share what is available, particularly with their offspring if it is growing nearby. Trees form communities, not only with other trees but with other plants as well, and communicate using chemical messaging both above ground through airborne molecules and underground through their root system which is connected to a mycelium network that can stretch over vast distances and carry chemical as well as electric impulses. Peter Wohlleben, a German forester and author, described this network as the Wood Wide Web, an advanced community that can share information and food and which is not that different to our own towns and cities. If tree behaviour is just a genetically programmed reaction to stimuli or if plants in general and trees in particular possess a form of consciousness and the ability to learn is an ongoing debate. It is however safe to say that it is time for us to look at trees with a more open mind just like our forbearers once did.

In the early 19th century forests had almost completely disappeared from Ireland. Back then only 1% of the country was covered in trees and only a small part of this percentage consisted of old growth woodland. The ancient forests that had once covered some 80% of Ireland’s landmass were all but gone.

How it had come to this almost complete deforestation is hard to understand especially if the role that trees had played in early Irish history is taken into account. Trees were often the spiritual centre for communities, they were the place to hold rituals, to pass judgement or to crown a new chieftain or king. From the earliest time these trees were treated as sacred and they were believed to have a deep connection to the Otherworld, the realm of spirits, fairies and other magical beings.

Certain trees and shrubs, hawthorn and blackthorn in particular, were seen as a portal to this Otherworld and deemed untouchable which is reflected in numerous legends and folk tales. These tales always follow the same line: An ignorant person interferes with a sacred tree or shrub, in Ireland often referred to as fairy tree or fairy bush, either by removing parts of the plant or chopping down the whole entity. What follows for the unfortunate person are various degrees of misfortune or even death. The believe in the connection of trees to the Otherworld lives on even into the present and fairy trees and fairy bushes are still very much respected. Not too long ago a section of a planned motorway in County Clare had to be redesigned to circumnavigate a fairy bush, an old hawthorn, that has a firm place in local folklore.

The tradition of the rag tree is related to the fairy tree and fairy bush. Here a piece of cloth taken from the clothing of a sick person is tied to the tree, usually a hawthorn which often stands close to a holy well, and it is believed that while the piece of cloth rots away so does the ailment of the patient. Today this tradition has somewhat escalated and often photographs, drawings, shoes, toys and other items can be found hanging from the tree and wishes are no longer restricted to the healing of an illness.

Ireland’s first written language also has a strong connection to trees. The Ogham alphabet which was in use from around the 4th to 8th century is often referred to as the tree alphabet. It consisted of 20 letters, each made of a combination of short vertical, horizontal and tilted lines. These letters were known as feda (trees) or nin (branch or fork) and according to some medieval texts each letter was associated with a specific tree. Today this theory is being contested for the simple reason that it would have been pretty much impossible naming all 20 letters after trees considering the limited number of species present in Ireland. In addition the Irish names of some of the trees start with the same letter, e.g. hazel (coll), holly (cuilend) and rowan (caerthainn) all start with a C. It is however still widely accepted that at least eight of the Ogham letters were representing a tree species. The B (breith) for example stood for the birch, the F (fern) for the alder and the D (dair) for the oak. It is now thought that the remaining letters were named with poetic alternatives that described characteristics of certain tress. The L (luis) might have stood for flame to represent the fiery red rowan berries and the T (tinne, meaning bar of metal or iron) might have stood for the dense, hard wood of holly.

Dating from the same time period as the Ogham alphabet are the Brehon Laws. This law system which was named after wandering lawyers, the brehons, is recognized as the oldest in Europe and remained in place almost unchanged for centuries. Under these laws trees and shrubs were granted special protection according to their importance to the community and the penalties for breaking these laws were severe. The trees were divided into four classes, roughly mirroring classes in early Irish society. These were the airig fedo, the nobles of the wood (oak, hazel, holly, yew, ash, scots pine and crab apple), the aithig fedo, the commoners of the wood (blackthorn, elder, spindle, whitebeam, arbutus, aspen, juniper), the fodla fedo, the lower divisions of the wood (alder, willow, hawthorn, rowan, birch, elm, cherry) and the losa fedo, the bushes of the wood (bracken, myrtle, furze, bramble, heather, broom, wild rose).

Despite their spiritual and practical importance woodlands seemed to have already been in decline at the time. Ancient law texts and other sources describe Ireland as a landscape of fields interspersed with single trees, rows of trees and small woodlands. Most of the big forests had already disappeared. In a 9th century text only few forested wilderness areas are mentioned: Fid Mar hi Cuailngi "the great wood in Cooley" (County Louth), Fid Deicsen hi Tuirtre "the wood of Deicsiu in Tuirtre" (around Slieve Gallion, County Tyrone) and Fid Moithre hi Connachtaib "the wood of Moithre in Connacht". Pollen records support these descriptions and it seems that Ireland had already lost most of its forest before the Norman invasion in the 12th century. This however doesn’t mean that the new ruling class took particular care of Ireland’s remaining woodlands. Forests were treated as a cheap resource there for the taking and a substantial amount of Irish timber made its way to England where it was used in all kinds of building projects from houses to ships. It is estimated that by 1600 only 12% of Ireland was covered in forests and continued exploitation brought this down to around 2% by 1800.

In the early 20th century a slow process of recovery began. Since then afforestation, forest management and conservation measures have increased the forest cover to around 11% which is still the lowest in Europe, where the average lies around 30%. The majority of these new forests are commercial conifer plantations where fast growing and non-native species like Sitka-spruce are the dominating plants and natives like yew and Scots pine only make an occassional appearance. Only around 25% of Ireland’s current forests consist of broadleaves and native trees like oak, ash, birch and hazel make up only half of that percentage.

Remnants of the old forests have only survived in a few small pockets mainly in the west of Ireland, for example in Glengarriff and Uragh in County Cork, Derryclare in County Galway, Old Head in County Mayo and St. John’s Wood in County Roscommon. The only extensive old growth woodland is the one around the Killarney lakes which today is the heart of the Killarney National Park. The park was established in 1932 when the Muckross Estate was donated to the Irish state as a memorial to Maud Vincent and named Bourn Vincent Memorial Park. Since then the area of the national park, now known simply as Killarney National Park, has grown considerably and encompasses an area of over 100 square kilometres protecting not only native forests but also lakes, rivers, waterfalls, mountains and areas of blanket bog.

Some parts of the Killarney woodlands have been around for some 9000 years. After the ice sheets of the last glaciation had disappeared the tundra-like landscape was soon colonized by the first trees: Birch, willow and hazel. The birch especially laid the groundwork for the future forests. The golden leaves that the trees scattered on the ground every autumn were vital to build up soil. In addition birch trees and some of its relatives like the common alder, which is also native to Ireland, formed symbiotic relationships with nitrogen-fixing bacteria. These bacteria form nodules in the tree’s root system where they produce nitrogen, a vital nutrient, make it available to the tree and also leak it into the surrounding soil which makes the ground more attractive to other plants.

As the soil improved these pioneer trees, which grow much faster than the big forest trees, soon established the first woodlands. A glimpse of what these early forests must have looked like can today be seen in the Burren, a limestone karst area that covers parts of County Clare and Galway. The Burren woodlands consist mainly of hazel with the occasional hawthorn, holly, ash and willow. Because these species don’t form a thick canopy, the Burren forests support a rich and varied field- and ground-layer. Primrose, wood anemones, bluebell, wild garlic, broad-leaved helleborine and other wildflowers as well as various mosses and liverworts thrive here throughout the year.

After the ground was prepared the giants of the forest appeared on the scene. Scots pine, elm and oak soon became the dominating species and the pioneer trees were downgraded to the shrub layer in the new forest hierarchy or they disappeared. Only a few birch forests managed to survive in some damp corners on the poor soil of the west coast or at the edge of peatlands. The new king of the forest, the oak, together with the elm, dominated the valleys while Scots pine took over the mountain slopes. Other species like rowan, whitebeam, holly, ivy and honeysuckle thrived in clearings and along lakes and rivers. These primeval forests covered much of Ireland bar the highest mountain tops and extreme coastal fringes and were home to a variety of animals. Some, like wolf, brown bear and boar, are extinct while others, like the fox, pine marten, and numerous birds, are still with us.

The oak forest of Killarney are the descendants of these primeval forests. Oak forests form a thick canopy and while the trees are in leaf the forest floor is cast in a permanent twilight. Nevertheless oak forests support a rich biodiversity. The individual oak tree is a small ecosystem in itself and several hundred species of plants and animals can live around, in and from an oak. Over 200 species of insects alone are known to dwell on a single tree. Bats often use old oaks to roost and birds like robin and blue jay like to nest high up in the canopy. In autumn acorns, the fruit of the oak tree, are an important food source for squirrels, who pick them directly from the tree, and the badger, who forages the fallen acorns from the ground. Soil can form in nooks and crevices and host wildflowers, epiphytes like the polypody fern grow directly from the bark and ivy, mosses, liverworts and lichen are also common hitchhikers. A survey conducted in County Mayo recorded over 50 species of lichen on one old oak tree alone.

The mild and humid climate of Ireland’s west coast is a major contributing factor that makes this rich biodiversity possible. Bryophytes in particular cherish the soft weather. A total of 129 of the 162 species known in Ireland thrive in the Killarney woodlands. These forests also have one of the richest variety of ferns in Europe. A total of 52 different species grow here including the royal fern that can reach a height of up to 2 meters. Smaller trees like rowan, holly and hazel are also often part of an oak woodland and woodrush and bilberry can be abundant on the ground. A special member of the Killarney oak woods is the strawberry tree. This evergreen species, like other members of the Lusitanian flora, has an unexpected and restricted range and can only be found on the Iberian Peninsula and the south-west and west of Ireland. Killarney National Park holds the largest strawberry tree community but the nearby woods of Glengarriff and Derrynane and the forests around Lough Gill in County Sligo are also home to this unusual and rare tree. Apart from its distribution the strawberry tree also has an uncommon fruiting cycle. In September and October, when most other plants only carry fruit, the Strawberry tree produces clusters of small, wind pollinated, white flowers. Once pollinated it takes a whole year for the flowers to turn into the characteristic red fruits that gave the tree its name and as a result the strawberry tree carries both flowers and fruit at the same time.

The sessile oak that makes up the Killarney oak forests is one of the two oak species native to Ireland and is overall the more common species. The sessile oak can tolerate poorer soils and because of this can thrive in the fertile valleys as well as on more exposed hillsides with poorer soils. The pedunculate oak on the other hand is a bit more demanding and chooses only nutrient rich and heavy soils which can be mainly found in the Irish midlands. The only significant pedunculate oak woodlands are therefore located right in the heart of Ireland at the Abbey Leix Estate in County Laois and Charleville in County Offaly. Both species look very similar and are known to hybridise. The safest way to tell them apart is the acorn. The pedunculate oak grows its acorn on a stalk while the acorns of the sessile oak are missing this feature. Both species have always been seen as supreme trees, masters of the forest, which is not surprising. Oaks can become true giants, reaching heights of up to 40 meters and an age of 500 years and more. There is still some discussion on where the oldest oak in Ireland can be found but the most likely candidate stands in the beforementioned Abbey Leix Estate, a pedunculate oak with an estimated age of 700 years. The majority of Killarney’s oak forests are not older than 200 years and only a few pockets of truly ancient woodland remain. These parts of the forest, like Derrycunnihy Wood, have a very special aura. You can feel the ballast of the years and the trees exude a watchful presence. The gnarled trunks and branches reflect the wisdom of centuries and it seems even the birds respectfully keep their voices down. In these places it is easy to belief that the forest itself is very much a conscious entity.

Reenadinna Wood has an equal respect inducing presence. This community of yew trees stands on an outcrop of limestone that separates Lough Leane from Muckross Lake and is the only surviving yew woodland in Ireland and one of only a few in Europe. The yew was among the first trees to arrive into Ireland after the last glaciation but only became widespread around 5000 years ago. This evergreen plant grows preferably on limestone and chalk and very likely has been a dominating species in the Burren before the arrival of men. Many place names like Mayo (Mhaigh-Eo), the plain of the yews, also suggest that the yew was once far more common than it is today. Today the yew is mainly known as a tree of graveyards. However many of these yews are only distantly related to the native yews that grow in the wild. The majority of the  graveyard yews are the offspring of a chance mutation in which the branches grow more or less straight upward unlike the wild yews that spread their branches far and wide. The mutation was discovered around 1740 in two plants that grew in the limestone hills of County Fermanagh. One of the unusual seedlings was moved to the landscaped gardens at the Flourenscourt estate. There the young yew prospered into a mature tree and was multiplied through cuttings which were given away to gardens and estates all over Ireland. Eventually this offspring became a popular garden variety and also found its way onto many cemeteries. The mother tree lives on until today in a quiet corner at Flourencecourt.

In Reenadinna the wild yews clench their roots into the fissured limestone and the low hanging branches create a cave-like space. It feels eerie and comforting in equal measures. This woodland has been occupying this stretch of land between the lakes for some 4000 years and some of the yew trees we see today have been standing for 200 years. Yews can live for a long time. On average they have a lifespan of 500 years and outside a forest setting they can reach an even greater age. The oldest yews in Ireland are around 800 years old and stand at the Crom Estate, County Fermanagh and the Fortingall Yew in Scotland, believed to be the oldest yew in existence, has an estimated age of 3000 years.

The eventual decline of the ancient Irish woodlands was a series of unfortunate events. It started with the arrival of the first humans around 9000 years ago. These early arrivals were Mesolithic hunter-gatherers and their need for firewood and building material for simple huts would have had only a small impact on the vast forests. The first noteworthy forest clearances happened in the late Mesolithic and early Neolithic. At that time the first farmers had started to create pastures for their animals, cattle, sheep and goats, and ploughed their fields where they grew early variations of wheat and barley. The first evidence of cereal pollen appeared some 6000 years ago and at the same time the amount of tree pollen fell substantially while the pollen of grassland flora, including ribwort plantain, dandelion, buttercups and grasses, was on the rise.

Around the same time a change in climate, a relatively dry continental pattern was replaced by the current mild and humid Atlantic regime, triggered the growth of blanket and raised bogs which engulfed vast areas of woodland especially in the west of Ireland. The Scot’s pine was one of the first victims of this event and despite some temporary re-colonization of the young peatlands during drier intervals, the Scot’s pine had disappeared from the country by the early bronze age. The petrified tree trunks that can today be seen embedded in the peat are a striking reminder of this period. The elm which had been, together with the oak, one of the main species of Ireland’s early forests also disappeared completely. It is thought that the combination of farming, where elm foliage was used as cattle fodder, and a disease similar to the Dutch elm disease which affected the species all over Europe in more recent times, lead to the disappearance of this mighty forest tree from Ireland by the 7th century.

A disease similar to the Dutch elm disease is currently threatening the ash, a tree that is quintessentially Irish in many ways. This tree is not only a native and integral part of woodlands and hedgerows, it is also the tree that traditionally provided the wood for the hurley, the stick used in Irelands national sports hurling and camogie which is a faster and more aggressive versions of field hockey. This disease, known as ash dieback, is caused by Hymenoscyphus fraxineus, a fungus that spreads through the air and eventually kills most of the trees that get infected. Ash dieback was first reported in Poland in 1992 and after making its way through Europe the fungus arrived in Ireland in 2012. Hymenoscyphus fraxineus is not native to Europe and was brought to Poland probably on the shoes of a traveler or on a shipping container from abroad. Milder temperatures caused by climate change allowed the spores to survive and find their first victim. Because the European ash had never experienced Hymenoscyphus fraxineus before, the trees had no defense mechanism and became easy prey for the fungus. If the ash will survive is unknown. Some trees reportedly withstand the infection longer than others, but a complete immunity or recovery hasn’t been seen yet. In a best-case scenario, the ash will develop a defense against the virus and make a comeback, in the worst case the tree will disappear from the Irish landscape.

By the middle ages the make-up of Ireland’s forests had already changed dramatically and reflected the growing human population. According to pollen record alder had become a dominating species and often grew together with hazel. Both species were widely used for material and food, hazel branches were made into wattle for various applications and the nuts provided an important and energy rich food supply. The alder due to its wide girth, which can reach up to ½ meter, was a main source for making shields.

During the 16th and 17th century new species were introduced into the country estates and formal gardens that had become a regular feature of the Irish countryside. Among them were beech, horse chestnut and sycamore, which all have become a common sight in Ireland. Especially the beech has established itself as a forest tree. In Killarney it thrives on the Ross Peninsula where it displays the typical vibrance of a beech forest with its wonderful combination of light green foliage on the trees and a cover of last year’s golden leaves on the ground. Another introduced species is the notorious rhododendron. In contrast to its spectacular flower display this evergreen shrub is a constant threat to the native flora. The rhododendron responds extremely well to the mild and damp climate and can take over vast areas very quickly. Because of its dense growth it kills off any competing plants quickly and effectively. The NPWS (National Parks and Wildlife Service) with the help of volunteers has been fighting a never ending battle against the rhododendron for many years, not only in Killarney but all along the west coast.

The difference between native and introduced, good and bad, is however not always clear. The Norway spruce for example didn’t make it into Ireland after the last glaciation and was recently introduced as a plantation crop mainly for Christmas trees. Cones found in County Antrim and County Mayo however show that the tree was growing in Ireland during an earlier interglacial period some 90.000 years ago. This raises the question what native really means. For how long does a species have to be gone from Ireland to become non-native and how long does it have to be growing or living in Ireland to become native? Nature is constantly changing and would do so even without human interference.

The pine marten is Ireland’s classic forest predator although the slender, elegant animal is not a pure carnivore and enjoys nuts and berries as well. By the early 20th century the pine marten was almost extinct, a combination of being hunted for its fur and the almost complete disappearance of its habitat reduced the population to only a few animals that hung on by a threat in a few secluded places along Ireland’s west coast. The introduction of forest plantations some decades later came just in time. While these monocultures have a bad reputation today they very likely saved the pine marten from extinction. The plantations provided shelter and created stepping stones in the landscape and slowly but surely the number of pine martens started to climb. Around the same time the grey squirrel, a North American native,  made its way into Ireland and because of its bigger size, faster breeding cycle and more aggressive attitude it started to replace the native red squirrel especially along the east coast and the midlands. In the early years of the 21st century conservationists feared the worse for the future of the cute, rust-coloured mammal. A survey conducted in 2007 however showed a surprising development. Grey squirrel numbers were in decline across the country and the red squirrel was making a comeback. The most likely explanation for this unexpected situation is the growing pine marten population. Red squirrels are the main prey for the marten but over millennia they have developed strategies to avoid or escape the hunter. To the grey squirrel on the other hand pine martens are a new threat which makes them an easy meal and it seems the pine marten population has taken advantage of that.

As we are travelling deeper into the 21st century and the impact of climate change and biodiversity loss is starting to show, the attitude towards forests in Ireland is changing and huge efforts to reforest the country are underway. Numerous private initiatives concentrate on establishing new and enlarging existing woodlands by planting native broadleaf trees like oak, ash and birch. Previous reforestation attempts had concentrated on fast growing, mostly non-native conifers. Unfortunately these commercial forests don’t have a long lasting impact on the natural world because like any crop-plant the trees are being harvested once they have reached maturity and what is left behind is nothing but a wasteland. To make a real difference in the current age of climate chance and biodiversity loss a long term approach is needed. This means planning and managing woodlands in a way that allows continuous regeneration while harvesting trees for commercial use. The solution are mixed woodlands with a combination of fast and slow growing species, the reintroduction of traditional forestry methods like coppicing and ongoing replanting. This will create forests that will exist for centuries, still produce a regular crop and at the same time host a rich plant and animal community.

Some environmental organisations suggest to allow at least some woodlands to regenerate naturally without human interference. These forests wouldn’t be used commercially but would be dedicated natural havens where wildlife can thrive without any disturbance from outside. The Burren National Park in County Clare is one of the places where this natural development can be witnessed in real time. To conserve the unique wildflowers of this karst landscape the Burren is currently being actively managed. Traditional farming techniques keep developing woodland in check and encroaching scrub is being cut back on a regular basis. Would we allow these shrubs to prosper the series of events that had taken place after the last glaciation would be repeated. Hazel, blackthorn, hawthorn and other shrubs would be followed by bigger trees and over time the Burren would revert back to a mixed forest. In some spots this process has already begun and ash and birch are already part of the hazel forests. If this approach would really work is however questioned by a long term experiment that was started at Lady Park Wood, a forested area at the border between England and Wales, in 1944. While some parts of the forest have developed an extremely rich and healthy biodiversity, other parts have gone the other way. Because Lady Park Wood didn’t exist in a bubble separated from the real world, invasive species still found their way in and unchecked grazers, because of the lack of natural predators, also did considerable damage. In other words to create a truly natural woodland we would first have to eradicate all invasive species like rhododendron and sika deer and reintroduce all extinct native species, especially predators like the wolf.

I have been living in a remote corner on the west coast of Ireland for almost 20 years now. As much as I love the ocean and the wide open skies, for someone who grew up not too far away from the Bavarian Forest and lived a decade near the Black Forest the lack of trees is hard to bare and at times I long for the embrace of the forest and the smell of damp leaves and moss. Studies have shown that spending time in the forest has not only a positive effect on our mental health but also results in physiological improvements like blood pressure reductions and a boost of autonomic and immune functions. Our species has been living in and from the forest for millennia and only over the past centuries have we turned away from our green home. The heritage however is inside us and somewhere deep down we are all still forest people.


Carsten Krieger, August 2020 / Edited December 2020