At the end of the 16th century, Ireland was still a relatively wooded country, with one-eight of its surface area covered in forests. Most of this woodland was of Oak, with Alder woods along the river banks. The Irish word for an Oak wood is ''diarbhre'' and that for an Oak grove ''doire''. The Anglicized versions of these are usually written as ''darraragh'' or ''dorrery'' and ''derry'' or ''der'' respectively. Of the 62,600 townlands in Ireland around 1,600 (2.5%) contain versions of either ''diarbhre'' or ''doire'' in one of its various forms, a testament to the importance of Oak forest in early Ireland.
In Elizabethan times, the extent of the forests in the southwest of the country was almost legendary. Accounts of the military campaigns of the English forces of Queen Elizabeth I at the end of the 16th century make it quite clear that these forests were a considerable natural barrier to troop movements as well as a place for concealment and refuge for the Irish armies and irregulars. In 1585, following the years of the Desmond Rebellion, Sir John Perrot, President of the council of Munster and thus Queen Elizabeth's representative in the Province suggested that the woods be cut to ''deprive the rebels of their place of succour''. It was about this time, too, that English settlers were planted in Munster on lands confiscated from the rebels. These settlers started the clearance of the forests for their own security and prosperity.
At the start of the 17th century in the counties of Cork, Kerry and Limerick, the woodlands were particularly extensive. In the west of County Cork, the valleys of Adrigole, Glengarriff, Coomhola, Bantry and Roaring Water Bay were clothed in
Oak, Birch and Arbutus. Further east, in the river valleys of the Bandon, Lee and Blackwater rivers, lay mile upon mile of forest. In Kerry, woods clothed the southern shores of the Shannon estuary. From Listowel, forest extended along the foot of the Stack Mountains to Tralee. Woods stretched eastwards from Tralee along the valley of the River Maine to beyond Castleisland and westward along the northern shores of the Dingle Peninsula to Mount Brandon. Oak forests grew around the Lakes of Killarney, while on the Iveragh Peninsula, many of the valleys cutting into the mountains were wooded, as were the headwaters of the Kenmare River.
In County Limerick, woodlands covered the northern slopes of the Mullagharerick Mountains, from Abbeyfeale to Newcastle West. The valley of the River Maigue was heavily wooded and woodlands extended westwards from this valley to Rathkeale and eastward into the Glen of Aherlow. Woodlands along the shores of the Shannon, east of Limerick City, also stretched southwards into the Golden Vale. In total around 390,000 hectares, 25%, of these three counties were covered in natural high forest.
In recent years, forestry planting of exotic conifers has been undertaken by the State Forestry Service, now known as Coillte Teoranta. Most of these plantations are on poor upland soils, in contrast to the natural forests of the 17th century, which rarely grew above the 500 foot (160 metre) contour. In the three counties of Cork, Kerry and Limerick conifer plantations are now abundant.