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Irish Woodlands

A woodland is a living community dominated by trees. A healthy woodland environment is made up of countless and varied plants and animals which have adapted to each other and lived together over thousands of years. Woodlands are a cherished feature of the Irish landscape. They play an important role in our lives. They provide wood for fuel, tool making or building, and they are increasingly important amenities. They are important reservoirs of wildlife - large woods can contain up to 5,000 species of plants and animals.

Woodlands in Ireland can be divided into three main groups: natural woodlands, conifer plantations and scrub woodlands.

Layers in an Irish Woodland

NATURAL WOODLANDS
A natural oak woodland consists of up to five woodland layers. At the top is the "canopy". This is made up of the crowns of neighbouring trees which branch out to meet and form a continuous layer of foliage. Beneath the canopy of the dominant trees is the 'understorey' which is made up of other smaller trees. Below this the shrub layer consists of medium sized plants like bilberry and honeysuckle. Under the shrub layer is the herb layer where shade-loving plants like ferns and an abundance of wild flowers are found. Right down on the ground are the mosses, liverworts and lichens which make up the moss layer.

The top layer of soil matter is called the "litter layer". This is made up of dead leaves, plants and animals. It is here that the worms and bacteria carry out the decomposition or recycling which is so vital, to return nutrients to the soil.

The nutrients released through decomposition of litter seep back into the soil and are absorbed by the roots of woodland plants. The top 30cm of soil has the highest nutrient content, but the roots of trees go much deeper.

CONIFEROUS PLANTATIONS
Coniferous plantations cover over 500,000 hectares of Ireland. These are usually single species woodlands , the most common being Sitka spruce and lodgepole pine. The trees are all planted at the same time and once the canopy has been established there is no understorey layer. The spruce and pine trees are evergreen which means that they do not lose their leaves in winter so little light reaches the ground.The needle-shaped leaves from conifers do not decompose as easily as those of deciduous trees and make the ground below them acidic. This impedes organisms such as worms and bacteria in carrying out their recycling work of putting nutrients back into the soil. Today grant schemes encourage more species diversity within plantations.

After 20 years coniferous plantations are thinned, and clearings may develop where heather and foxgloves can move in. The tall trees which are left behind only have branches up high so that animals like deer can move about freely below. The tree tops are used as lookout points by many species of birds.

Another animal which has benefited from the spread of conifer plantations is the pine marten which had become almost extinct. It is a very agile tree climber which lives on small mammals, birds and insects. Pine martens are over two feet long with a dark brown fur coat and bright beady eyes.

SCRUB WOODLANDS
The best-known scrub woodlands in Ireland are the hazel scrubs in the Burren of north Co. Clare. The shallow soil here and the prevailing wind prevent the trees growing above three or four meters in height. A rich carpet of moss usually covers the ground. Ferns and wild flowers are plentiful.

HISTORY OF IRISH WOODLANDS
In prehistoric times woodland covered much of the landscape of Ireland. Vegetation scientists record that Irish woodlands reached their maximum extent some 7,000 years ago. The most common trees were oak, elm, ash, Scots pine and alder. Between 5,000 and 6,000 years ago the first farmers began to clear woodlands to create farm land.

By Celtic times there was a lot less woodland in Ireland, but trees and other woodland plants were protected by law. The most important trees were the seven so-called "nobles of the wood" - oak, hazel, holly, yew, ash, Scots pine and crab-apple. Under what is known as Brehon Law any person who damaged one of these trees had to pay a fine of two milch cows and a three year-old heifer!

From the 16th century on tree clearances accelerated as the ruling English Government needed timber for building and industry. With the population twice what it is today, there was increased use of timber for fuel. By the 1900s only 0.5% (35,000 hectares) of the land area of Ireland was covered by woodland. Since state planting began the area of woodland has increased to over 600,000ha, though 84% of this is non-native conifer species.

Oak and hazel have always been highly prized in Ireland as we see in these lines from an Irish poem of the twelfth Century:

Forest Cover decline in Ireland to the 1900's and the projected forest cover by the year 2050 AD.

THE VALUE OF TREES
Trees renew the air that we breath by absorbing carbon dioxide and producing oxygen. This process is called photosynthesis. Trees take a great deal of water in through their roots every day and release it as oxygen through tiny holes in their leaves. This helps to keep land well drained.

The roots of trees are often very long and deep, branching out under the soil. This not only holds the trees firmly in the soil, but also keeps the soil from being washed away. These are just some of the reasons why we should protect trees and woodlands.

THREATS TO WOODLAND
Any change in the conditions within a woodland can be a potential threat to wildlife, though some change can be good as it encourages diversity. However, many plants and animals depend on undisturbed conditions, and when conditions change they simply die out. For example a woodland food chain could look like this: leaves are eaten by insects which in turn are eaten by birds and small mammals. If the insects are removed the birds have nothing to eat so they have to leave too.

Clearance of woodland for agricultural use has been by far the most damaging change. Overgrazing by animals such as deer and sheep is also a problem in many parts of the country. In the National Parks of Kerry and Donegal the biggest problem is an invading plant species - Rhododendron ponticum, which was introduced in the nineteenth century. This non-native shrub has taken over large areas of natural woodland, and is being removed to allow for natural regeneration to occur in the woodland. Other threats to woodlands are from neglect, drainage, fire, hedgerow removal to enlarge fields and the planting of non native stock.

WHAT CAN I DO TO HELP?
Much work is being done, but still only 9% of the land area of Ireland is under woodland: this is the lowest in Europe apart from Iceland. The European Union average for woodland is 31% so we have a long way to go. It is hoped that we will have 16% of the land of Ireland under woodland by 2035. This will be a great achievement, but it will still leave us at just over half the E.U. average.

You too can help by supporting the many organisations which work to protect woodlands including the Tree Council of Ireland, Coillte, The Forest Service, Trees for Ireland and Crann. You can also help by acting responsibly when visiting woodlands and forests, following the country code.

Dúchas, The Heritage Service is responsible for all the National Parks as well as many other parks which include natural woodlands They have also established a network of National Nature Reserves which are designed to conserve wildlife habitats.

FURTHER READING
de Buitlear, Eamon (1984) Wild Ireland. Country House, Dublin
Kelly, F. (1999) Early Irish Farming. Dublin Institute for Advanced Studies
O'Connell, C. A. (1999) Wild Woods of Ireland Field Studies Guide. Irish Peatland Conservation Council, Dublin.
Tree Council of Ireland (1999) The Tree Day Resource Pack/CD ROM. Tree Council of Ireland, Dublin.