Aotearoa is home to over 70 naturally rare ecosystems - places that make up a tiny amount of the total area of New Zealand but can hold incredible amounts of biodiversity.
Jamie, Kauri and Clement at the top of a scarp looking for gentian at Waipata reserve. Photo: RNZ / Claire Concannon
Follow Our Changing World on Apple Podcasts, Spotify, Stitcher, iHeartRADIO, Google Podcasts, RadioPublic or wherever you listen to your podcasts.
Naturally rare ecosystems happen when there are distinct environmental conditions within a geographically small area; whether it is the underlying rock, the soil chemistry, the climate in the region and/or the local effects of volcanic, geothermal, river, or ocean activities.
Braided riverbeds, coastal turfs, shingle beaches, salt pans, volcanic lahars, tarns and cushion bogs are all examples of naturally rare or naturally uncommon ecosystems in Aotearoa.
These specific landscapes, soil chemistries and conditions have given rise to unique flora and fauna that live in these places. So what you get is a set of rare, endemic (found only in Aotearoa), plants and animals dependent on specific ecosystems and restricted to very small areas.
And many of these are threatened.
Gentianella calcis subspecies calcis. at Awahokomo in the Waitaki valley. Photo: John Barkla
In the Waitaki Valley area of North Otago limestone ecosystems are rare and in decline. When it breaks down, the limestone rock produces rich fertile soil good for farming, and the stone itself is quarried for building. So the land has been extensively modified, and the areas suitable for limestone endemic plants has shrunk.
One of the biggest problems for the limestone-soil specific plants is non-native grasses such as Chewings fescue. The grasses smother the plants, blocking out light, sucking up all the moisture and building big impenetrable root mats that stop new plant seedlings from establishing. The low growing natives just can’t compete, and so their numbers have been dwindling.
Dr. Clement Lagure and Tom Waterhouse at Oamaru DOC field station nursery. Clement holds Gentianella calcis subspecies manahune. Tom holds Lepidium sis Photo: RNZ / Claire Concannon
At the back of the Department of Conservation’s Oamaru field station DOC ranger Tom Waterhouse has been growing these limestone endemic plants in a nursery. But as science advisor Dr. Clement Lagrue explains, the longer-term issue is where to put them. Intensive monitoring and hand weeding have saved the plants from extinction for now, but to allow them to flourish a habitat ‘reset’ might be what is required.
University of Otago Botany Masters student Jacinta Steeds is trying to investigate what scale of reset is needed. She is running a field trial on small plots of land to look at what type of weed removal works best.
Working with Te Rūnanga o Moeraki and their biodiversity restoration team Whiria te Waitaki, Tom, Clement and Jacinta hope to develop a plan to safeguard the future of this rare and threatened ecosystem.
Kaiaka tāiao Jamie, Patrick, Mauriri, Kauri and Les from Whiria te Waitaki led by Te Runanga o Moeraki. Photo: RNZ / Claire Concannon
To learn more
- Visit the New Zealand Plant Conservation Network website. Plants discussed in this episode include: Gentianella calcis subsp. calcis, Lepidium sisymbrioides and Carmichaelia hollowayi.
- Listen to John Barkla discuss the issues facing rare native plants, in Favourite plants.
