Tree Species
NATIVE SPECIES
Native species are those that have arrived naturally on the island of Ireland and have been here since post glacial times.
Veteran oak ( photo A. Pfeifer)
Ireland lost most of its flora and fauna during the Ice Age as plants and animals retreated south in the path of the advancing glaciers. When this cold period was eventually over some 10,000 years ago the land was recolonised by species that crossed via land bridges that existed between Ireland, Britain and the continent. Some species, however, did not arrive in time as the land bridges disappeared under the rising seas from the glacial melt waters. As a result, some common tree species that are native to the continent are not represented in the native Irish flora such as beech and Norway spruce. Beech succeeded in crossing to the south of England but did not arrive naturally in Ireland.
Most of our native trees are broadleaves such as oak, ash, birch etc while conifers are represented by only three species– Scots pine, yew and juniper – the latter being only a shrub. Conifers form only a very minor part of the native species resource and consequently reference to native species usually means native broadleaves.
Currently, native species form only a small percentage of our forests due to their low productivity in relation to introduced species. Native broadleaves are more difficult to grow requiring sheltered fertile sites and a high degree of silvicultural skill if productive stands of quality timber are to be achieved. Better quality of land is, however, becoming available for afforestation in farm forests and along with attractive grants and premiums, native broadleaf species are being planted in higher numbers than any time since the start of the afforestation programme which began in the 1920s. Scots pine is also being planted but mostly as a nurse species in mixture with broadleaves.
Native species are being planted not only for timber production but also to encourage and enhance biodiversity in our forests. Native trees have a long association with many indigenous animals and plant species and provide rich and diverse habitats that are not seen in stands of introduced species, particularly conifers. Old forests and stands of native species are important islands of native biodiversity and it is from these areas that native plants and animals spread to new habitats. Their conservation and enhancement is therefore an important objective in forest management which today is also concerned with the environmental sustainability of the forest resource.
Information on individual tree species is available through the following links:
Our Trees – a guide to growing Ireland’s native trees
INTRODUCED SPECIES
Irish forests comprise mostly non-native tree species which have been deliberately introduced by man over the last 200-300 years. These species have proven to be more productive than native species particularly on wet, infertile and exposed sites. Conifer species from the coastal regions of Washington and Oregon in Northwest America, which have a similar climate to Ireland, have proven to be well adapted to Irish conditions. As a result they have been widely planted in the national afforestation programme, which for many years was confined to the poorer site types.
Sitka spruce (photo W. Baxter)
The use of non-native species has given Irish foresters a wider range of options in matching species to appropriate sites than would be the case if only native species were available. Attributes such as resistance to exposure, low nutrient requirements, fast growth rates, straight stems and good timber properties are to be found in many of the non-native species either singly or in combination. Through selecting the appropriate species for a site, foresters are able to ensure the successful establishment and subsequent growth of a plantation. This is particularly important in commercial plantations where the rapid establishment and good growth of crops are required to ensure a return on investment.
Agriculture in Ireland relies on non-native species for food production and similarly forestry has come to rely on non-native species for timber production. Today, almost all the timber harvested annually comes from stands of non-native species, and while the wisdom of this is questioned by many environmental groups, the result is that a viable forest industry has been developed with an estimated annual turnover in excess of 200 million euros.
Currently there is a re-balancing of the species composition of our forests with a greater emphasis being placed on native species. Non-native species, however, will continue to form a major portion of our forests for the foreseeable future. The diversification policies that have been introduced will, in time, create more mixed forests with both native and non-native species contributing to a more diverse and sustainable resource.
Information sheets on all the common tree species found in Irish forests are available on the Forest Service website in the section Irish Forest Species.
A description of the first forestry species trials established at Avondale is outlined in The Avondale Initiative 1905