Around 12,000 years ago, Ireland was covered in snow and ice. This was known as the Ice Age. As the weather became warmer, the snow and ice melted and trees began to grow. The seeds of trees such as hazel and oak were brought here by birds and animals, across the landbridges from Britain and the rest of Europe. The seeds of other trees, such as willow and birch, are so light that they were blown here by the wind.
Eventually, the seas rose, the landbridges were flooded and Ireland became an island. Our native trees are the trees that reached here before we were separated from the rest of Europe. Our most common native trees include oak, ash, hazel, birch, Scots pine, rowan and willow. Eventually, people brought other trees, such as beech, sycamore, horse chestnut, spruce, larch and fir to Ireland.