The ark and the algorithm
How did a stinky, ugly plant become a higher priority for protection than the kauri tree? In part one of a two-part series, Charlie Mitchell examines how an official ranking of our endangered species came to be.
The little plant by the lake appears to be dying. Orange bubbles cling along its stem like pustules, and it looks dry, wilted – like a figure slowly decomposing.
It’s a jarring presence in the high country, not far from the Powerade-blue lakes that feature heavily in New Zealand’s branding.
You likely wouldn’t notice the small herb, flattened against the dry earth, in such a vast landscape. What betrays the plant, brings it to your attention, is the smell for which it was named. The New Zealand fishguts plant smells even worse than it looks.
The fish-guts plant does not appear on our tourism posters, and has never made it on to a commemorative stamp. Very few people know it exists at all, and fewer have actually seen, or smelled, one.
The little public information that exists remarks on its awful smell, and how it is a close relative of the stinky goosefoot – a plant that is slightly less rancid but significantly more popular – but little else. Even its scientific name, detestans, haunts the fishguts plant, stamping it with unpleasantness.
At the other end of the country, in a sprawling patchwork of wetlands in northern Waikato, a beautiful orchid exists in solitude.
The swamp helmet orchid is a tiny plant with a maximum height of 3cm and an extremely limited range: its entire New Zealand population is confined to one arm of the swamp, where only a couple of hundred orchids remain, blazing brilliantly red like rubies in the mud.
The swamp helmet orchid is so rare, and such a tempting target for orchid thieves, that its exact location is a government secret. When a photographer from New Zealand Geographic went on an expedition to take photos, he was escorted by a Department of Conservation (DOC) ranger to its location, an hour-long slog through the bog, at times chest-deep, under the condition no photos were publicised that would reveal its exact location.
Like the fish-guts plant, the swamp helmet orchid once had a wider habitat, until humans transformed the land for their own purposes. Much of the country’s wetlands have been drained, leaving species like the orchid with few places to survive.
New Zealand has tens of thousands of obscure plants, many of which are threatened in some way.
But the fish guts plant and the swamp helmet orchid are notable for one reason: last year, they were listed as ‘‘priority species’’ by DOC, under a proposed strategy to figure out which of our threatened species most needed to be saved.
It was an ambitious task that resulted in a 150-strong list. It included kiwi, ka¯ ka¯ po¯ , Hector’s dolphin, the great white shark and tuatara; species that are generally considered important for conservation, animals that people know and like.
What was interesting about the list were the outsiders, the little-known species elevated to the rank of those listed above, like the fish-guts plant and the swamp helmet orchid.
They weren’t the only obscure ones.
The list also included seven types of scurvy grass and 17 snails; it featured a beetle that exists in only one patch of grass on a large rock in Hauraki Gulf, and a stick insect species of which only two have ever been found, on a single branch of a tree in Northland.
It did not include kauri, weka or the orange-fronted parakeet; not one of our thousands of fungi species, and no spiders, not even the katipo.
So how did a rancid plant and an orchid few people will ever see make it on to such an important list? And did they deserve their place?
It’s a conundrum that highlights the moral issues that have come to define modern conservation, and the choices that have to be made.
The global rate of extinctions is now 1000 times the natural rate, according to a United Nations panel on biodiversity. Limited resources mean only some species can be saved, and prioritising some can mean condemning others.
Because of its high rate of threatened species, New Zealand is on the forefront of making choices around a tough question that has echoes of Noah’s Ark: which species most deserve to survive?
The algorithm
To a layman, the algorithm is indecipherable; strings of bracketed phrases, drawing information from lengthy spreadsheets that detail every aspect of some of our most threatened species: how rare they are, how many family members they have, whether it’s endemic to New Zealand.
The threatened species algorithm was deployed by DOC last year to create the list of 150 priority species, which had been intended to become government policy. (The new Government is expected to announce its own policy in the coming months, and it is unclear whether the prioritised-species list will remain, or expand.)
It took about 500 of our managed native species – only a small fraction of all species, but those with the most complete data – and put them to the whims of the calculations underpinning the algorithm.
The formal name for this approach is ‘‘systematic
conservation planning’’, but it can be thought of as a type of triage for our dying biodiversity. It’s an idea that started in academia but has only in the last decade become a matter that drives government policy to decide where scarce conservation resources are allocated.
Tools like the algorithm, which use the cold logic of data to inform what are otherwise deeply emotional decisions, have become a dire reflection of the natural world’s health; given limited resources, which species deserve to be saved, even if that means others will be left to die?
Whether the priority list survives or not, it is a fascinating case study into how decisions are made around prioritisation, which will only become more relevant.
The ranked list, obtained under the Official Information Act, gives an insight into the trade-offs, and what we value most about our unique species.
The species ranked first is the Castle Hill buttercup, a tiny scree plant that evolved to exist in a very specific location, the broken limestone debris on the slopes of Castle Hill in Canterbury.
There are only 67 plants left, all within a 6ha reserve among the boulders that made the landscape famous. The reserve was the first ever set aside to protect a single plant. Dr Lance McCaskill, who led the effort to protect the buttercup in the 1950s, described its fate as an ‘‘age-long euthanasia’’, threatened by introduced weeds, grazing sheep and wild rabbits.
Two factors counted in the buttercup’s favour. It was named an iconic species, automatically putting it in the top 50; and it has a very high threat ranking at its genus level, Ranunculus.
(The algorithm took into account threat rankings at the order, family, genus and species level. Order is the broadest category of those – humans, for example, are one of hundreds within the primate order, one of eight within the Hominidae family, and the only species of Homo sapien.)
You could easily imagine an alternative weighting producing a different result.
Our most unique species, by far, is the tuatara. It is endemic at an order level – that means it has no living relatives, because they all died long ago.
The buttercup has relatives at order level, family level, and genus level – it’s unique only at species level, and even that is debated. It scores high because much of its genus is threatened, but it has plenty of more distant relatives.
If we prioritised uniqueness, we might not focus on the Castle Hill buttercup. We would defend the tuatara at all costs, because it has no parallel. But tuatara were ranked 29 because they have a stable population, and the fact they have no living relatives means their genus, family, and order are not threatened, because it’s the only one. Their uniqueness, in some ways, counts against them.
Another thing you could prioritise is representativeness – choosing a range of species across all kingdoms, recreating a pale imitation of the diversity that used to exist. That list would not include all five kiwi species, because they are closely related. It might not include takahe¯ , which are closely related to pukeko, which are safe. It certainly wouldn’t include 17 snails.
Could you imagine a politician unveiling a list of priority species that excluded kiwi or takahe¯ ? Would people care about conservation if the species people like the most could be excluded at the expense of a lichen or an earthworm?
The global rate of extinctions is now 1000 times the natural rate, according to a United Nations panel on biodiversity.
Tomorrow: The other ways of choosing which species to save