The Network has developed five criteria for the identification of Important Plant Areas in New Zealand. Some sites may meet more than one criterion. All sites must be discrete management units and not large expanses or whole regions of the country.
The site supports significant populations of one or more species which are of global or Oceanic conservation concern. This includes populations of New Zealand’s acutely threatened plant species (Critical, Endangered and Vulnerable) and ‘At Risk’ species (Range Restricted and Sparse) - based on de Lange et al 2009. Species of global conservation concern are those threatened species that are New Zealand endemics or whose distribution is largely (over 75%) within New Zealand. In terms of significance IPAs should be selected only for populations which are viable or for which ameliorative measures can be taken to ensure a return to viability. Consideration should be given to the geographical spread of the species, so that both core and edge of range populations are included in the New Zealand IPA network.
The site has an exceptionally rich flora in an Oceanic context in relation to its biogeographical zone. The co-occurrence of a large number of species and the existence of a high diversity of habitats are both expressions of floristic richness. Assessments of floristic richness should be based on comparative data that can be related to the national resource, rather than on subjective judgements or local opinion. Areas that support more than a given percentage (e.g., 25%) of the plant species native to a country may be considered to be exceptionally rich.
The site is an outstanding example of a habitat or plant community type of global or Oceanic conservation and botanical importance. This will itself have to be measured by criteria to evaluate the size, quality and distinctiveness of the plant community. It will include New Zealand’s naturally rare and nationally threatened plant communities (see Landcare’s rare ecosystem classification)
The site supports species or vegetation that is regarded of national cultural importance. An example might be the sites where kopi trees (Corynocarus laevigatus) support dendroglyphs on the Chatham Islands.
The site holds significant populations of one or more species or habitats or plant communities of regional conservation concern within New Zealand. These plant species or communities may be common nationally but within a region maybe extremely scarce.