Before European settlement, forests of Kauri, Agathis australis, covered 1.6m Ha in the northern half of the North Island of New Zealand. This ancient species of an ancient genus has been present in New Zealand since before the break-up of Gondwana, though it is thought that, after New Zealand was twice submerged beneath the ocean, the islands were recolonised by other descendants from the same generic ancestors. After two centuries of logging, burning and wholesale clearing, the extent of the ancient Kauri forest has been reduced to less than 7,000 Ha. The destruction of native forest was greatly accelerated by the introduction of the Brush-tail Possum (Trichosurus vulpecula) which overran both islands and is still destroying native forest much faster than it can be restored. In the lowland areas of the North Island and in the northern South Island may be found two species of Antarctic or Southern Beech, Nothofagus solandri (Black Beech) and N. truncata (Hard Beech).
Red beech (N. fusca) grows in the lowlands especially along the inland river valleys where soils are fertile and well drained. Silver beech (Nothofagus menziesii) the commonest forest emergent in Fjordland, grows at higher elevations with greater rainfall. Mountain Beech (N. solandri var. cliffortioides) grows in the mountains and on less fertile soils than silver beech, often forming the tree line at high altitudes. These beech forests, which have escaped clearing because they grow on mountain slopes considered unsuitable for agriculture, are the largest forests to survive in New Zealand. In the south-western quarter of the South Island is Te Wahipounamu World Heritage Area; two-thirds of its 2.6 million Ha is covered with forests of Antarctic Beech and Podocarpus species, including individuals thought to be 800 years old.