Late eocene to early Miocene vegetation and climate history of New Zealand

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Abstract
There were some major shifts in species dominance in the vegetation of the Late Eocene to Early Miocene in New Zealand. In the Middle Eocene (Bortonian) the vegetation was dominated by Casuarina and several species of Proteaceae. This association was replaced in the Late Eocene (Kaiatan) by one dominated by the Nothofagus fusca group, in which Casuarina was of minor importance. In the latest Eocene (late Kaiatan and Runangan), the Nothofagus fusca group was replaced by the Nothofagus brassii group, which remained dominant until the Early Miocene. The dominance of Nothofagus in the Late Eocene to Early Miocene indicates that the climate was predominantly cool-temperate. At the maximum cooling in the Early Oligocene, the Nothofagus brassii group was abundant. The vegetational data do not support the interpretation, based on oxygen isotope studies, that the climate was warm-temperate throughout much of the Late Eocene. Although there is no complete modern analogue of the Late Eocene to Early Miocene vegetation of New Zealand, a “best fit” might be the cool-temperate rainforests of the New Guinea highlands, where rainfall is about 1500 +mm per annum, mean annual temperature ranges from 13 to 18°C and there is only minor seasonal variation. Although these forests have Nothofagus brassii group as a dominant component, they also contain several plants (e.g. Anacolosa, Santalum, Cupaniae) that are often used to indicate tropical and subtropical climate.