From the first botanical expeditions to the subantarctic islands in the mid-1800s through to the present day, botanists have been intrigued by the subantarctic flora. The plants in many of these islands are most similar to those in the Aotearoa New Zealand flora, but some of the large and colourful species found there, including megaherbs, are unique. Here, Botany Curator Heidi Meudt focuses on the flora of Motu Maha Auckland Islands as well as some of the threats to its continued existence.
A familiar yet unique flora
Motu Maha Auckland Islands share a number of plant species and genera with Aotearoa New Zealand. Due to their smaller size and remoteness, these islands have a much smaller flora, with around 200 species of vascular plants, representing less than 10% of the mainland New Zealand flora which has about 2300. In addition, the islands contain a number of unique species not found in mainland New Zealand, or indeed anywhere else in the world.
The very colourful, deeply pigmented flowers of the subantarctic flora are another point of contrast to the white flowers of many mainland New Zealand species. The islands are also known for their large, showy “megaherbs”, which will be the focus of another blog.
Joseph Dalton Hooker and the first Flora
British botanist Joseph Dalton Hooker, from the Royal Botanical Gardens, Kew, was the first to publish a flora of the Auckland Islands based on his own observations and collections. As the assistant surgeon and naturalist aboard the HMS Erebus on the Ross Expedition (1839–1843), and only 23 years old when the expedition started, Hooker spent three weeks on Motu Maha Auckland Islands (and two days on Motu Ihupuku Campbell Island) in November and December 1840.
During those weeks, Hooker made hundreds of plant collections on the islands and later published his findings in the first volume of his Flora Antarctica series, Botany of Lord Auckland’s Group and Campbell’s Island (published 1844-1845), documenting some 370 species and including illustrations (by Walter Hood Fitch) of 150 of them.
A selection of illustrations in the Flora Antarctica (Walter Hood Fitch, Public domain, via Wikimedia Commons):
A flora “unrivalled in beauty”
In the introduction to his Flora, Hooker provides a realistic description of Motu Maha Auckland Islands and the elevational zones of vegetation that cloak them.
The first zone to greet visitors to the island is the tight band of forest dominated by rātā (Metrosideros umbellata), which also contains woody species of Dracophyllum, Coprosma, Veronica, and Raukaua, as well as ferns, including the ubiquitous Polysticum vestitum.
Next comes the broad belt of shrubland up to about 300 m above sea level, which is often quite thick and difficult to navigate, especially as there are few tracks, and none where we ventured.
Fortunately, the vegetation eventually opens out into tussockland slopes and is easier to navigate when carrying large packs!
And finally above 400 m elevation, we reach our favourite area, the alpine zone.
Hooker was a big fan of the alpine zone here too, noting, “It is especially towards the summits of these hills that the most striking plants are found, vying in brightness of colour with the Arctic Flora, and unrivalled in beauty by those of any other Antarctic country.”
The upland habitats of Motu Maha Auckland Islands are dominated by tussockland, bog and fellfield habitats, and this is where many of the island’s endemic flora can be found, including those shown in the next section below.
A list of all vascular plants of Motu Maha Auckland Islands
Since Hooker’s Flora, several other botanists have added to our knowledge of the subantarctic flora, including those who have attempted to compile lists of all the vascular plants found there. Johnson and Campbell (1975) compiled a list of all vascular plants of Motu Maha Auckland Islands, which was updated by Meurk (1985) to comprise 228 species, of which 187 (82%) are native and 41 are introduced.
Most of these 187 native species are shared with mainland Aotearoa New Zealand, several are only found in the subantarctic islands, and a handful are only found on Motu Maha Auckland Islands.
Some of the Motu Maha Auckland Islands endemic plant species are shown below, i.e. Azorella schizeilema, Gentianella cerina, Cardamine latior, and Geum albiflorum.
Threats to the flora: pigs and weeds
Compared to mainland New Zealand, where introduced plant species outnumber natives, Motu Maha Auckland Islands have relatively few weeds. Nevertheless, they still pose a threat to native species. However, the largest threat by far is feral pigs.
Invasive predators have largely been eradicated from most subantarctic islands. This includes several smaller islands in the Motu Maha Auckland Islands group, such as Adams, Enderby, and Disappointment Island. However, the largest island, Auckland Island, still has feral pigs, cats, and mice.
These predators have decimated bird and invertebrate populations on Auckland Island, and they also negatively affect native plants (Chimera et al. 1995; Campbell & Rudge 1984). For example, pigs dig up and eat native plants (they particularly like Anisotome antipoda) and destroy their habitats.
The Maukahuka Pest Free Auckland Island project is a detailed plan to rid the island of pigs, cats and mice. Unfortunately – and heartbreakingly so – it is now largely on hold since the Covid-19 outbreak, although some research from their team is still ongoing.
Looking ahead
As mentioned in the previous blog in this series, the main aim of our 2023 Strannik Auckland Island Expedition was to update the list of all vascular plant species (both natives and weeds) found on the islands by compiling new data on their presence, distribution and abundance, and photographing them all.
In a future blog post, we’ll share some of our preliminary observations and findings. But the next blog in the series will introduce you to the Strannik team and showcase some of our favourite places and plants from the expedition.
Further reading on the flora of Motu Maha Auckland Islands
- Department of Conservation (NZ). Auckland Islands. Accessed 17 Oct 2023.
- DJ Campbell & MR Rudge (1984) Vegetation changes induced over ten years by goats and pigs at Port Ross, Auckland Islands (Subantarctic). New Zealand Journal of Ecology, 7, 103-118.
- C Chimera, MC Coleman & JP Parkes (1995) Diet of feral goats and feral pigs on Auckland Island, New Zealand. New Zealand Journal of Ecology, 19(2), 203-207.
- JD Hooker (1844) The Botany of the Antarctic Voyage of H.M. Discovery Ships Erebus and Terror in the Years 1839-1843, Under the Command of Captain Sir James Clark Ross. Vol. I. Flora Antarctica. Part 1. Botany of Lord Auckland’s Group and Campbell’s Island. Reeve, London. 208 pp.
- (1975) Vascular Plants of the Auckland Islands, New Zealand Journal of Botany, 13(4), 665-720.
- (2013) Floral biology and flower visitors on subantarctic Campbell Island, New Zealand Journal of Botany, 51(3), 168-180.
- CD Meurk (1982) Supplementary notes on plant distributions of the subantarctic Auckland Islands, New Zealand Journal of Botany, 20(4), 373-380.
- WRB Oliver (1951) Botanical Discovery in New Zealand: The Resident Botanists. Joseph Dalton Hooker – (the British Antarctic Expedition). School Publications Branch, New Zealand Education Department.
Exquisite images – well done!
Thank you very much Denis, and thanks for reading the blog. It was almost too easy to take good photos in such a stunningly beautiful place! I think I came home with over 4000 images!