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Flora and fauna

Until the end of the Middle Ages, the land was heavily forested. Native species include deciduous trees such as oak, ash, hazel, birch, alder, willow, aspen, elm, rowan and hawthorn, as well as evergreen trees such Scots pine, yew and holly. Today, only 8% of Northern Ireland is woodland, and most of this is non-native conifer plantations.

As of the 21st century, Northern Ireland is the least forested part of the United Kingdom and Ireland, and one of the least forested countries in Europe.

The only native reptile in Northern Ireland is the viviparous lizard, or common lizard, which is widely distributed, particularly in heaths, bogs and sand dunes. The common frog is a very widespread species. Some lakes support internationally important bird populations, Lough Neagh and Lough Beg hold up to 80,000 wintering waterfowl of some 20 species, including ducks, geese, swans and gulls. The otter is the fourth largest land mammal in Northern Ireland. It can be found along the river systems, although it is seldom seen and will avoid contact with humans. 356 species of marine algae have been recorded in the northeast of Ireland; 77 species are considered rare.