Nicola Arndt und Matthias Pohl - Neobiota

secondary in origin but include stands on ancient woodland sites and old plantations dating from the
18 th and 19 th centuries. During the early part of the 20 th century a policy of afforestation was
introduced and this gained momentum during the last 4 decades of the century when extensive areas of
marginal land were planted. The majority of these plantations consist of introduced coniferous species,
principally sitka spruce (Picea sitchensis) 1 and lodgepole pine (Pinus contorta) which grow rapidly on
the mostly poor land – principally upland soils, blanket peats and heavy gleys – selected for
afforestation. Today, forest and woodland covers 626,000 ha or c. 9.0 % of the land area and the
national policy is to increase the forest estate to 17 % of the land area by 2030 (ANON. 2000a).
2 The character of existing native Irish woodlands
O’SULLIVAN (1998) estimated that not more than 100,000 ha, or 1.5 % of the land area, consists of
broadleaf woodland – including scrub, mostly in stands of less than 100 ha and many very much
smaller. More recent surveys indicate that there are c. 77,000ha of native woodland, excluding scrub
(HIGGINS et al 2004). Most of these stands are of native species, although they include beech (Fagus
sylvatica) and other non-native species. Despite their size they are very important as a reservoir of
native species and are recognised as a major repository of biodiversity. They can be broadly
categorised as follow (CROSS 1987a):
• Remnants of the original forest (ancient woodland), mostly confined to the poorest sites, greatly
modified and often over-exploited or largely abandoned silviculturally.
• Old plantations, 150 to 200 years old, often with beech, larch (Larix decidua), Scots pine (Pinus
sylvestris) and other exotic species, and probably with foreign provenances of native species.
• Secondary woodland of relatively recent origin on abandoned farmland and cutaway bog, often
scrub-like and with the better quality timber commonly selectively removed.
• Recent plantations, mostly of ash, oak and beech.
The species complement of native Irish woodlands is considerably poorer than other European
countries because of the separation of the island from the continental land mass relatively early after
the last glaciation (Table 1). Oak (Quercus species), ash (Fraxinus excelsior), birch (Betula species)
and alder (Alnus glutinosa) are the commonest canopy-forming species and hazel (Corylus avellana),
holly (Ilex aquifolium), hawthorn (Crataegus monogyna) and sally (Salix cinerea ssp. oleifolia) are the
commonest understorey species. Several species which occur in Britain and the nearby continent are
absent, most notable of which are important components of the forest climaxes, such as beech,
hornbeam (Carpinus betula), lime (Tilia species), sycamore (Acer pseudoplatanus) and field maple
(A. campestre). Some of these have been widely planted and regenerate spontaneously, especially
beech and sycamore. Scots pine, formerly widespread, is generally considered to be extinct as a native
species, although it may have survived until c. 1,000 years ago (BUDD & VON ENGELBRECHTEN 1999).
It is now widespread as a result of its re-introduction 200-300 years ago, mostly from Scotland, and it
regenerates freely on suitable soils. Certain shrub species, common in forests elsewhere in western
Europe, are very local or rare within Irish forests, e.g. Frangula alnus, Prunus padus. The herbaceous
flora is also impoverished, with species such as Mercurialis perennis very rare and possibly not native.
In contrast ash, which in drier climates thrives principally only in valleys and other moist sites, is
1 Nomenclature for plants follows TUTIN et al. (1964-1980); for animals EU Council Directive 92/43/EEC final
version.
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