New Zealand’s historically rare terrestrial ecosystems set in a physical and physiognomic framework

Terrestrial ecosystems that were rare before human colonisation of New Zealand often have highly specialised and diverse flora and fauna characterised by endemic and nationally rare species. Although many of these ecosystems are under threat from anthropogenic modification and their biodiversity values are declining, they still are not adequately identified by current land classifications. We compiled a list of 72 rare ecosystems from the literature and by canvassing New Zealand ecologists and land managers. Rare ecosystems are defined as those having a total extent less than 0.5% (i.e. < 134 000 ha) of New Zealand’s total area (268 680 km²), and the resultant list includes both well-recognised and less well known ecosystems. To define the ecosystems in a robust fashion we developed a framework based on descriptors of physical environments that distinguish rare ecosystems from each other and from more common ecosystems. Using this framework the 72 rare ecosystems are defined using pertinent environmental descriptors selected from soil age, parent material, soil chemistry and particle size, landform, drainage regime, disturbance, and climate. For each ecosystem, an example locality and the dominant vegetation structural type are also given.