In defence of DoC

Written by      

Peter de Lange with Peter Heenan

On October 25, 2004, the New Zealand Herald ran a cover story un­der the headline “DoC losing battle to save rarest species”, proclaiming that the New Zealand Department of Conservation (DoC) was simply unable to protect all threatened spe­cies, and that consequently many might become extinct or key popula­tions die out. The main species to feature were animals, such as the kakapo, kiwi, Hookers sea lion and katipo. One mysterious Canterbury plant was also mentioned but no name was given. While it cannot be denied that these organisms occur in much lower numbers than in the past, and some do indeed face pos­sible extinction, their parlous plight is in no way indicative of the state of the wider field of threatened species managed by DoC.

I have worked for the department for 15 years on threatened-plant con­servation management. Unlike much of its fauna, New Zealand’s flora has never been specifically protected by law. The only attempt to see that it was took place in the 1930s, when a small group of alpine-plant enthu­siasts sought legal protection for native plants. Their lobbying resulted in the Native Plants Protection Act of 1934, a quaint piece of legisla­tion which by today’s standards offers minimal deterrents to plant collection. A promised schedule of “threatened plants” was prepared but never appended. Nevertheless, this act stands as the only enforce­able law protecting the country’s indigenous flora outside the DoC estate. Legend has it that the only time the act was invoked—when the roadside pohutukawa of an irate resident on Auckland’s North Shore was trimmed by the local council—it was ruled that pohutukawa was not a plant but a tree, and the case was thrown out.

New Zealand’s threatened plants continued to receive minimal atten­tion until the mid-1970s, when Dav­id Given, of the Botany Division of the old Department of Scientific and Industrial Research, started a register of threatened natives, and then, in 1981, wrote Rare and Endangered Plants of New Zealand, an excellent popular account of the plight of New Zealand’s flora. Given was also the first to draw up lists (with regular updates from 1976 to 1990) of threatened species rated according to the degree of threat. Initially he used the International Union for the Conservation of Nature (IUCN) Red Data Book categories of “extinct”, “endangered”, “vulnerable” and “rare”. Recognising, however, that New Zealand had many uncom­mon but not necessarily threatened species, Given also introduced the term “local” to cover these. Given’s last sole-author listing in 1990 noted 270 plant species as threatened and a further 99 as local.

Since then the process of listing has been undertaken by the New Zealand Threatened Plant Com­mittee (three lists being published between 1993 and 1999) and its successor, the DoC-sponsored New Zealand Threatened Plant Panel (which has published two lists, in 2002 and 2004).

Though well understood by botanists, listing has been confused by conservation biologists with the internal ranking system used by DoC for prioritising the management of threatened species. DoC’s priority categories have been equated with IUCN threat categories, leading some to claim erroneously that in­creasing numbers of plants are under threat.

In fact, since the introduction of Given’s lists the numbers of seri­ously threatened vascular plants(ferns, conifers and flowering plants) have by and large fallen. Publica­tions within the peer-reviewed literature document a battle being won rather than lost. For example, in 1995 319 vascular plants were considered threatened; by 1999 the figure had fallen to 107. Furthermore, the number of extinct species has remained static at four, with the last presumed extinction—of Adams mistletoe (Trilepidea adamsii)—tak­ing place 50 years ago.

However, in 2002, following the implementation of DoC’s new system for classifying threatened and uncommon species, the number of threatened species rose by 111. Sev­eral factors contributed to this jump.Firstly, the classification system used by the New Zealand Threat­ened Plant Committee had been de­vised for plants only, while the new system was designed for all organ­isms. Adjustments to accommodate animals with small populations were needed. A small population can be an indication of an animal’s immi­nent extinction, but for New Zealand plants small populations are often normal. Such plants, therefore, though listed as “threatened”, were also marked “ST” (stable) or “RC” (recovering) to indicate that they were not actually at risk of extinc­tion.

Secondly, this was only the second time that the entire vascu­lar flora of some 2345 named taxa had been assessed for threat status since 1976. Finally, the system used between 1993 and 1999 applied a very conservative definition of “threatened”. Many taxa previously categorised as “declining”, “recover­ing” or “naturally uncommon” were now listed as “chronically threat­ened” and/or “at risk” even though their numbers had not necessarily declined.

The 218 plant taxa now assessed as “threatened” by DoC, only 122 would have been considered acutely threatened by the New Zealand Threatened Plant Committee, and of these, 13 noted as “stable” and/or “recovering” do not require conservation management. Since 1999, therefore, there has been a net gain of two “threatened” taxa—and this despite the fact that 12 newly described taxa have been placed in the threatened-plant category.

These figures, I believe, show that the plight of New Zealand threat­ened plants is not nearly as bad as was implied by the New Zealand Herald and other media. In fact, the number of threatened plants in New Zealand has remained fairly static over the last 10 years (about 5 per cent of the total flora). The question is whether this result stems from conservation effort or other processes. The Herald article has been interpreted by many as proof that DoC is incapable of managing threatened species appropriately. Is this true?

The question is not as easily an­swered as asked, and statistics don’t always show what they appear to. Some of the reductions in numbers of threatened plants that occurred in the 1990s were attributable to reclassifications following field dis­coveries. For example, the endemic Three Kings Islands tree Elingamita johnsonii, rated as “vulnerable” by the IUCN Red Data Book, was de­scribed in 1951 using sparse material from West Island. Recent and more thorough examinations of this most inaccessible islet have shown that Elingamita is common and occurs also on two adjacent rock stacks. Provided these places remain rat free, Elingamita is not threatened, so has received the new conserva­tion assessment “range restricted”. Comprehensive field surveys have reduced the high IUCN threat status of many other plants.

Although field surveys do not actually entail conservation management, if species’ threat levels can be reduced by the simple expedient of ascertaining their precise status in the wild, surely that is a very cost effective means of reducing the number of taxa requiring direct management. Thirty plant taxa were removed from the threatened-spe­cies list in 2004 simply because field surveys had shown them to be more common than previously believed.

New species are another complication. We keep discovering them, and most are rare or threatened: were they otherwise they would have been discovered earlier. For example, the accidental discovery in 1990 by Dr Brian Molloy of a wheat grass growing on limestone at Castle Hill, Canterbury, has resulted in significant new plant discover­ies on other Canterbury limestone outcrops. Specimens of some of these plants are now being held as safeguards by botanic gardens while they are formally described. A recent Landcare Research monograph on New Zealand gentians recognised five new Gentianella from the south­ern Marlborough, Canterbury and northern Otago limestone areas.

Taxonomic changes are a further factor that muddles the numbers. For instance, of 49 taxa discarded from the threatened-plant lists, 14 were removed because new research had shown they were not taxonomi­cally distinct. A further two species were removed because research had shown them to be failed weed introductions from Australia.

Such arguments aside, is their any evidence that DoC can manage threatened plants successfully? Heaps of it. A small cotula daisy, Leptinella filiformis, once believed extinct and then rediscovered in 1999, is now considered extinct in the wild as its only known habitat was completely destroyed by land developers. Luck­ily DoC and Landcare Research staff foresaw the threat and passed specimens on to botanic gardens, nurseries and specialist native-plant growers. As a result the species has been reintroduced to the wild at several sites, and is also for sale in some garden centres. It can even be seen growing wild in several lawns in urban Auckland. A plant saved by botanists!

The Kermadec koromiko (Hebe breviracemosa), long believed extinct, was rediscovered on Raoul Island by a goat hunter in 1983. Cuttings were raised on the island and in New Zealand, but scientists remained perplexed. How had a species last seen in 1908 reappeared in 1983 when it came from a genus that produced seed only viable for a year or two? Secondly, why did the wild plant fail to throw any seedlings, despite the production of viable seed that could be germinated easily in a nursery?

In 1997, members of the DoC weed team stationed on the island discovered 50 more plants when abseiling down cliffs, thus confirm­ing that the species had probably survived undetected for all those years on cliff faces inaccessible to goats. However, seedlings remained elusive until DoC eradicated rats on Raoul in 2002. Since then they have appeared throughout the island. It now seems likely that seedlings or seeds were being browsed by rats. Currently the world population of the Kermadec koromiko stands at 225 individuals (116 wild and 109 planted), and indications are that within the next 10 or so years this species will have recovered sufficiently to be removed from the threatened-plant list.

Holloway’s crystalwort (Atriplex hollowayi), recognised as new to science in December 2000, is New Zealand’s only endemic strand plant. Growing at or near the high-tide mark on Northland’s sandy beaches, the species was reduced to one indi­vidual in the early 1990s. However, its specific germination and habitat requirements were deduced, and now, through dedicated manage­ment, Holloway’s crystalwort has been brought back from the brink of extinction. So far this season (spring 2004), 80 natural seedlings have appeared and more are expected. These will continue to be supple­mented with cultivated plants. Al­ready the species has been returned to three of its former beach habitats, and so successful has management been that there are plans to return it to parts of its former range near Auckland and in the Bay of Plenty. Barring mishap, its status may soon be reduced from “nationally critical” to “nationally endangered”.

The Three Kings kaikomako (Pennantia baylisiana), often touted as “the world’s rarest tree”, has also undergone a management boost. Known from just one natural specimen on Great Island (Manawa Tawhi), it was long believed func­tionally extinct because the sole survivor was a female. Through a combination of horticultural per­severance and scientific research, flowering plants raised from cuttings from the wild tree have produced viable fruit, as have seedlings raised from these. As a result of information obtained from these studies, the wild tree has also been induced to set viable fruit, and early in 2004 some of these germinated on the island. Though clearly a long way from se­curing the species, management has progressed significantly, and now not only is it anticipated that additional wild plants will be produced, but, should either these or the wild tree fail, there is a large mainland seed bank of genetically pure P. baylisiana to draw upon.

A last example is the coastal pep­percress (Lepidium banksii), one of a group of plants that kept scurvy at bay among Cook’s crews. Of all New Zealand plants this is the one with a death wish, being prone to innumerable attacks by bugs and diseases, having suffered frequent mishaps of nature and nowadays found only in a couple of spots on the Nelson coast. Nevertheless, it has been managed very successfully and rescued from the very brink of extinction. A hundred and eighty-eight adult plants are known from several sites, 12 the result of natural recruitment, the rest of deliberate plantings. Without management, this species would have become extinct by the late 1980s.

While it is true that for some species appropriate management solutions have not yet been deter­mined, and that in some instances we might even be losing the battle, it is clear that in plenty of cases we are winning, both as regards particular species, such as the ones described here, and on the broader front of safeguarding ecosystems. New Zealanders need to hear the good stories about conservation along with the bad. Concerning plants, the stories are mostly good.

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