Rare ecosystems

  • Image, Rare ecosystems.

    Rare ecosystems either naturally cover very small areas or have very little of their original extent remaining. Their conservation priority is determined by their threat of collapse.

    We classified Rare ecosystems as a case study.

    Key findings

    In 2014, New Zealand had 71 identified rare ecosystems, with 45 of them threatened with collapse.

    • Of the 45 threatened ecosystems, 18 were classified as critically endangered (the highest level of threat), 17 as endangered, and 10 as vulnerable.
    • Inland and alpine systems had the largest number of rare ecosystems (30), with just over half (16) threatened.
    • In contrast, 10 of 13 coastal ecosystems and 10 of 15 wetland ecosystems were threatened.
    • The three rare ecosystems induced (created) by indigenous vertebrates were classified as critically endangered (the highest level of threat). An example is fur seal haul-out sites, where the seals create unique habitats by disturbing plants and animals at places where they exit and enter the water.
    Note: Rare ecosystems were identified by expert opinion and represent <0.5 percent of New Zealand’s land area. Ecosystems are grouped into classes for this summary based on Williams et al (2007). The subterranean basalt fields ecosystem (classed as subterranean or semi-subterranean ecosystems) has not been graphed but was classified as data deficient.

    Definition and methodology

    Rare ecosystems were identified by experts on the basis that they each covered less than 0.5 percent of the land area of mainland New Zealand. The rare ecosystems were subjected to the International Union for the Conservation of Nature’s (IUCN) Red List criteria for ecosystems to classify their threat status (Holdaway et al, 2012). These assess ecosystems against four criteria:

    1. short-term decline
    2. historical decline
    3. small current distribution or very few locations
    4. very small current distribution.

    The assessment criteria are then refined using subcriteria to identify the threat status of each ecosystem. Ecosystems not threatened with extinction are classified as least concern. Least concern indicates there is still a threat to the ecosystem, but it is not currently a conservation priority. Where there is insufficient data to classify an ecosystem, it is classified as data deficient.

    Data quality

    We classified Rare ecosystems as a case study.


    relevance-partial This case study is a partial measure of the ‘Impacts on biodiversity’ topic.


    accuracy-high The accuracy of the data source is of high quality.

    See Data quality information for more detail.

    Supporting information


    Holdaway, Robert J., Wiser, Susan K., Williams, Peter A. 2012. Status Assessment of New Zealand's Naturally Uncommon Ecosystems. Conservation Biology. 26(4): 619-629

    Williams, PA, Wiser, S, Clarkson, B, & Stanley, MC (2007). New Zealand's historically rare terrestrial ecosystems set in a physical and physiognomic framework. New Zealand Journal of Ecology, 31(2), 119–128. Available from http://newzealandecology.org/nzje.

    Published 21 October 2015

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