Origin of New Zealand's Kauri‐Broadleaf Forests

We present a descriptive model to account for the origin of New Zealand's northern kauri‐broadleaf forests that integrates tectonic, distribution, ecological, and phylogenetic data. We propose that this flora represents a remnant of a central North Zealandia biome. We discuss the evidence that supports the existence of land along the Loyalty Ridge‐Three Kings Ridge‐Northland Plateau terrane and the Norfolk Ridge, which collided asynchronously from the Middle Eocene (north) to Early Miocene (south) allowing metapopulations to expand southwards along the collision zone between 30–23 Ma. Distribution data, fossil records, and available molecular phylogenies for twelve tree species are summarised. The fossil record shows that extant species first appeared in New Zealand at the Oligocene‐Miocene boundary and were not part of a pre‐Neogene flora. Individual molecular phylogenies were converted into areagrams and analysed to produce a general areagram showing the hierarchical structure of North Zealandian areas. New Zealand plus the Three Kings Islands are sister areas to Norfolk Island plus Lord Howe Island, forming a distinct southern North Zealandian clade.