About 1,000 of our known indigenous taxa (800 species and 200 sub-species) are now considered threatened. These figures relate only to the 'higher' organisms whose conservation status has been studied - plants, animals and fungi. Nearly 300 threatened plants and 500 animals have been listed by the Department of Conservation (1992b; 1994b and 1994e), while scientists at Landcare Research have compiled a list of more than 200 threatened fungi (Buchanan and Beever, 1995). Some endemic micro-organisms (bacteria, protozoans and algae) may also be threatened, though research on these groups has tended to focus on their effects on health, soil and water rather than assessing their conservation status.
The Department of Conservation has ranked 403 plant and animal taxa as having conservation priority (categories A, B and C). These include all of our endemic frogs and mammals, more than three quarters of our endemic birds, more than a third of our reptiles and freshwater fish, and most of our giant land snails and giant wetas. A further 389 threatened plants and animals are unranked (categories I, O and X). Most of these are category I species and subspecies whose rarity is known, but whose precise status is uncertain because of insufficient information. Two dozen are category X speciesthose which have not been seen for several years and are possibly extinct (10 plants, 12 invertebrates, 1 bird and 1 bat). A further 40 of the unranked taxa are category O speciesplants and migratory birds which are threatened in New Zealand but have secure populations overseas. The Department also lists a further 19 taxa which have special importance in Māori culture and are rare or localised. These include half a dozen plant species introduced by early Māori settlers.
Given that most of our fungi and invertebrate animals are still unidentified, the true number of threatened species may be several times higher than the above figures - though the evidence to date suggests that it is larger organisms that are most at risk. Continuing pressure on habitats and vulnerable populations is likely to push the number even higher in the next century. It is also possible that, even among the known species, the level of threat is higher than currently thought. In keeping with overseas practice, the Department of Conservation (1992b and 1994b) has taken the safety threshold for plant populations to be about 500 and, for animal populations, about 1,000. Recent work in population genetics, however, suggests that the 'safe' long-term population size may be closer to 5,000 (Lande, 1995).
Despite these uncertainties, the news, for some species at least, is not all bad. In the two years between the compilation of the 1992 list and the 1994 list, the conservation status of several species improved (e.g. the Canterbury mudfish, black mudfish, yellow-eyed penguin, Mahoenui giant weta and Chatham Island pigeon). The improvements resulted from conservation programmes to control predators, protect habitats and translocate species to a safer area. Surveys also turned up both new species and 'new' populations. Four new galaxiids were found in Otago and one each on the Chatham Islands and Stewart Island. New populations of black-eyed gecko, North Island kokako, Northland tusked weta, Banks Peninsula weta, the Canterbury mudfish, and the tussockChionochloa spiralis were all found. (A special area at Dog Kennel Creek has been designated to protect the best-known mudfish site.) However, these good news stories were the exception rather than the rule. The surveys showed that most threatened species were as critically threatened as before (Department of Conservation, 1994b).
To many people bacteria are synonomous with disease, although most of the naturally-occurring bacteria in our soils and waters and on our bodies are harmless or beneficial. Globally, less than 5,000 species have been described, but scientists now think many more may exist, perhaps numbering millions, and perhaps even outnumbering all other species. Bacteria have been around for so long that most known species are almost global in their distribution.
New Zealand has less than 300 described species and most of these are also known from other parts of the world. Estimating the number of unknown species is nearly impossible, but a conservative estimate may be obtained by looking at the other species which live here. It is generally assumed that most 'higher' species harbour at least one, and sometimes several, unique species of bacteria which have evolved to live exclusively in or on them. If so, New Zealand might have at least 80,000 species of symbiotic bacteria alone. The free-living species would take this number even higher.
Nobody knows how many bacteria are threatened. In fact, the very concept of threatened bacteria seems profoundly odd because we are so used to hygiene practices and antibiotics aimed at eliminating bacteria from our bodies, food and water. But some of New Zealand's bacteria may be threatened, especially those that have evolved to live symbiotically on threatened plants, animals or fungi, and those which are endemic to threatened geothermal locations (Holmes, 1996).
Since we have at least 800 threatened plant, animal and fungi species, and several degraded hot pools and geysers, the total number of threatened bacteria could be more than 1,000 species. The geothermal bacteria are particularly interesting because their unique chemistry enables them to withstand extremely high temperatures. Many of our hot pools have come under considerable pressure in recent decades (see Chapter 7). One example of a hot pool species that could be vulnerable is a green sulphur bacteria called Chlorobium tepidum. This may be endemic to New Zealand and is known from only four hot springs, including a drain beneath a hotel (Holmes, 1996).
Apart from endemic symbionts and geothermal bacteria, few concerns are held for most types of bacteria. In fact, with so few species identified to date, scientists are far more interested in detecting bacteria than protecting them, both to combat harmful species and to harness useful ones. Despite the successes of modern antibiotics and public health systems, many harmful bacteria are still with us, such as food-poisoning ones like Campylobacter, Salmonellaand Shigella (Public Health Commission, 1994). Other harmful bacteria include Meningococcus (which causes meningitis) and the deadly Mycobacterium tuberculosis(which causes the lung disease, Tb, and is increasing in many areas of the world, including parts of New Zealand). Nuisance blooms ofcyanobacteria are also a problem in nutrient-rich streams, ponds, and lakes.
But not all research is preoccupied with problem bacteria. In recent years the spectacular progress in biotechnology has enabled bacterial genes to be harnessed for the production of medicines and useful industrial compounds (such as enzymes for cleaning up oil spills). Since the two bacterial domains contain greater genetic diversity than the rest of the living world, bacteria are now being seen as an unexplored goldmine (Holmes, 1996). From this perspective, rare species, such as the hot pool bacteria, are potentially valuable resources.
The number of known protozoan species in New Zealand is roughly 2,600 (see Table 9.1) but the real figure may be as high as 7,000-8,000, made up of roughly 3,500 marine species, 3,500 soil and freshwater species and 1,000 parasites. Most of the known species are marine protozoans, as these have been the best described to date (Dawson, 1992). Soil and freshwater protozoans remain poorly documented (Hayward, 1980). Their presence in soil is generally taken as a positive indicator of soil health, but their presence in water is more often taken as a sign of health risk.
About 10 percent of the known species are parasites recovered from fish, birds, reptiles, domestic and feral mammals, and humans. A large amount of research has focused on these parasitic and symbiotic species, particularly those which cause disease (e.g.Giardia lamblia, Cryptosporidium). More than a dozen protozoan parasites have been recorded in humans in New Zealand. Four of these are endemic New Zealand species which colonised humans after we had colonised the country. The other human-dwelling protozoans arrived with us from other parts of the world.
Nearly half the known parasitic protozoans are exotic species which live inside our introduced birds and mammals and were imported with them. However, many more indigenous parasites probably live in our endemic birds, reptiles and land invertebrates. No protozoans are known to be threatened in New Zealand, despite the efforts of public health experts to reduce the numbers of some of the harmful ones. In fact the health risk from waterborne and food-borne protozoans appears to have increased in recent years (see Chapter 7, Box 7.6).
Many unrelated groups of photosynthesising protists are called 'algae'. For convenience, they are often lumped into two broad groups according to their sizethe macro-algae and the micro-algae. The macro-algae, or seaweeds (consisting of Brown algae and the multi-celled species of Red and Green algae) attach themselves to rocks or other hard surfaces and grow like plants. In contrast, the tiny micro-algae, or phytoplankton (i.e. the Dinoflagellates, Diatoms, Euglenoids, Yellow and Golden algae, and the single-celled species of Red and Green algae) either float near the surface or form thin coverings over rocks.
Micro-algae occasionally form visible blooms of phytoplankton in the sea and in polluted freshwater, and slippery green coatings of periphyton on rocks in streams. A small number of species are toxic (see Chapter 7, Box 7.11). Generally micro-algae are invisible except as coloured stains in the water, froths on the sand at high water mark, scums on ponds, or coloured mats below hot thermal pools (Cooper and Cambie, 1991). New Zealand has more micro-algae species than it has vascular plants, but few of these are endemic. The number of known species is about 2,800, three-quarters of which live in freshwater and a quarter of which live in the sea. Diatoms are the most diverse of the micro-algae kingdoms, making up 25 percent of the freshwater species and more than 60 percent of the marine species.
In the past century, some micro-algae have increased to nuisance levels in many streams, wetlands and shallow lakes (see Chapter 7). The causes are increased sunlight, where riverbanks have been cleared of native forest, and increased nutrient pollution from farm run-off and sewage discharges. One group of marine micro-algae, the dinoflagellates, has recently become more widely known because of the appearance of several toxic species (see Chapter 7, Box 7.11). It is not known whether marine micro-algae are generally becoming more or less abundant.
New Zealand has a rich diversity of seaweeds (Adams, 1994). Approximately 15 freshwater species and about a thousand marine species are found here. About 40 percent of these are endemic. Little is known about the distribution, ecology and status of most species. Many are still undescribed and many of those which have been described require major taxonomic revision (Nelson, 1994a). Although none appear to be threatened, some have specific niche requirements and are very localised in distribution (e.g.Gelidium allanii, G ceramoides) while others are vulnerable and may merit monitoring. These include:
- endemic species with very restricted distributions (e.g.Perispoochus regalis, Carpococcus linearis);
- epiphytic species attached to hosts with very restricted distributions (e.g. Porphyra kaspar); and
- species that are known from only one location or a very small number of collections (e.g. Codium platyclados, Chnoospora minima, Amplisiphona pacifica ; Palmophyllum umbracola, Porphyra woolhousiae).
Seaweeds vary widely around our offshore islands. To the south, Stewart Island and the subantarctic islands have rich and diverse seaweed communities. To the north, the Kermadec Islands have some species that are closely related to those in far off warm regions of the Pacific and Indian Oceans. Some other island groups have their own endemic species (e.g. Three Kings and Chatham Islands).
Brown algae are the most common and largest seaweeds. Globally, they number at least 100,000 species, are almost entirely marine, and are all multi-celled. They range in size from microscopic threads to huge kelps up to 70 m long. The bull kelp ( Durvillaea antarctica) is the world's fastest-growing organism, capable of growing 2 m in a day. It is especially noticeable in cool, shallow waters where it forms brown, ribbon-like, 'forests'. It was abundant off the South Island's east coast until recent decades. Sedimentation has been identified as a possible cause of its decline (Royal Society of New Zealand, 1993). Competition from invasive alien seaweeds, such as the brown seaweeds, Undaria pinnatifida and Colpomenia durvillaei, may also be a threat (Nelson, 1994b).
Red algae exist in single-celled and multi-celled forms. The latter are almost entirely marine. They form branching structures or broad, flat, plates and ruffles. Some of the more complex red algae grow up to a metre, though most are small and delicate. The red alga Pterocladia lucida is harvested commercially to produce high quality agar which is used in laboratories as a food source for micro-organisms grown in petri dishes . The status of red seaweeds in New Zealand is unknown.
Most green algae are single-celled and live in freshwater or sometimes on moist land. A number, however, are multi-celled and form small ribbon-like seaweeds and algal 'turfs' on the coastal seabed and on stream and lake beds. Their status is unknown, though many are a nuisance in freshwater, where their population blooms are associated with the eutrophication of streams and small lakes.
Our only non-algal 'seaweed' is a flowering plant, sea grass (Zostera novazelandica). It has apparently declined around our coasts as a result of sedimentation caused by coastal developments such as harbour and marina construction, channel dredging, spoil dumping and stormwater runoff. Efforts are being made to restore it (Turner, 1995).
New Zealand's turbulent history of isolation, inundation, uplift, and ice age has left its mark on the indigenous plants (see Box 9.12). Many (80 percent) are endemic, that is they are are found nowhere else in the world. It has also allowed us to retain a rich mixture of primitive non-vascular plants (e.g. mosses) but has limited the diversity of our higher vascular plants (trees, grasses and other flowering plants). This can be seen in New Zealand's relatively low ratio of vascular to non-vascular plants. While the world in general has 9 or 10 vascular plants for every one non-vascular species, we have only 2 native vascular plants for every non-vascular one. In other words, vascular plants make up more than 90 percent of the world's land plants, but only 70 percent of New Zealand's. Having high endemism makes the conservation of New Zealand plants that much more critical: if New Zealanders do not look after their unique plants, no one else can.
In recent years, the Department of Conservation and the New Zealand Botanical Society have produced lists of the plants considered threatened (Cameronet al., 1993, 1995; Department of Conservation, 1992b, 1994b). The Botanical Society's list is considered definitive by all parties, while the Department of Conservation's list has the more restricted purpose of ranking threatened species for conservation management purposes. The criteria for both lists therefore differ slightly.
Although the two threatened plants lists are in broad agreement, the Society's list is longer than the Department's because it includes a greater number of plants which are: taxonomically indeterminate (i.e. undescribed plants whose taxonomic status still requires clarification); and insufficiently known(i.e. where the identity or status of the plant is poorly understood). Unlike the Department, the Society also includesrare species (i.e. those with limited numbers or distributions, but which are not threatened at present) and 'local' plants (i.e. those with limited distributions that warrant monitoring).
As a result of these differences, the Department of Conservation lists a total of 302 plant taxa as threatened (including not only full species, but also threatened sub-species and varieties) while the Botanical Society lists 319 (and an additional 142 classed as 'local').
The Department's list includes 199 full species of vascular plants, representing about 10 percent of our known vascular plants, and 85 full species of non-vascular plants (8 percent). Taken together, the Department and Society lists indicate that 8-10 percent of our native plants are at risk, with the percentage rising to almost 14 percent if rare and locally restricted species are included.
The Department and the Society are mostly in agreement on another small list of plants, though they use different terminology to describe it. The list consists of a dozen species, 9 of which are 'presumed extinct' by the Botanical Society, and 10 of which are defined more optimistically by the Department of Conservation as 'species which have not been sighted for a number of years, but which may still exist' (see Table 9.6). Both organisations consider a taxon extinct when it is "no longer known to exist in the wild after repeated searches of the type localities and other known places".
One plant generally accepted to be extinct is Adams' mistletoe (Trilepidea adamsii). Noted for its tubular red flowers and shiny leaves, the mistletoe was known to exist in only a few areas north of Hamilton. It has not been seen since 1954 (Given, 1981; Norton, 1991; Wilson, 1992). The mistletoe's demise followed a series of increasingly fatal encounters with the main forces that have ravaged New Zealand's ecosystems during the past 700 or so years. First, deforestation by Māori and then European settlers collected the plant for its attractive flowers.
Introduced mammals added to the pressure on the mistletoe by helping to reduce the native bird populations which normally dispersed the mistletoe seed. Ultimately, however, it was the human factor that delivered the coup de grâce. Collectors and artists sought specimens of the very pretty, but increasingly rare plant, with ever greater determination, and eventually it was almost picked out of existence. New Zealand has been left a wealth of fine paintings of Adams' mistletoe, but the plant has gone. Over-collecting has been a persistent factor in the decline of several rare New Zealand plants.
Threatened plants are not limited to one or two particular habitats. About a fifth are in wetlands, where drainage and intruding species have been major pressures. Another fifth are in coastal ecosystems, where the degradation of dunelands and ecological changes caused by the decline in seabird and marine mammal colonies have been significant sources of pressure. Other significant homes of threatened plants are inland rocky habitats, scrub areas, tussock/herbfield ecosystems, and, last of all, lowland forests (see Tables 9.7 and 9.8).
Several long-lived shrubs and small trees are known only from fragmented, ageing and non-regenerating populations. They are failing to reproduce because ecological processes, such as pollination and seed dispersal, which were once carried out by native birds and other animals, no longer occur. These 'living dead' plants include such highly threatened species as the shrubby tororaro(Muehlenbeckia astonii) and the unusualHelichrysum dimorphumwhich, as the name suggests, can take on two very different forms: either a small shrub or a scrambling vine.
Not all threatened plants face such a bleak future, however. Occasionally a species given up for dead surprises the experts. The nodding greenhood orchid (Pterostylis nutans), for example, had not been seen for many years and was considered either extinct or extremely vulnerable. It has recently been discovered in at least two central North Island locations.
Plants evolved from multi-cellular green algae, probably in estuarine areas, about 460 million years ago (Niklas, 1994; Palmer, 1995b). Fungi were also colonising the land around this time and particular species formed associations with the new plant species, defending them against other fungi in exchange for food. Those first plants were liverworts, mosses andhornworts. They make up the most primitive division of the plant kingdomthe Bryophytes. Because they had no vascular tissues to store and circulate fluids within their bodies, these early land plants were unable to survive far from water. They formed low green mats on moist surfaces. Today, about 16,000 species are known worldwide, more than 1,000 of them in New Zealand.
The first vascular plants evolved about 410 million years ago. CalledCooksonia, these 10 cm long plants were vine-like, without leaves or roots, but with vascular systems that enabled them to redistribute water and nutrients inside their tissues (Palmer, 1992). They subsequently gave rise to upright plants - ferns, whose leafy fronds could catch falling water and whose rhizomes (underground stems) could absorb it from the soil. They were followed about 380 million years ago by the first trees, cone-bearing gymnosperms. Meanwhile, the mud and sediment that eventually became New Zealand had not even begun to accumulate in the sea floor. The great Permian extinction came and went, then the continent of Pangea split into smaller continents, including Gondwana. When the New Zealand landmass was finally thrust out of the sea as an appendage to the Gondwana coastline, these early plants were waiting to come aboard.
That was about 135 million years ago, and as our first kauris, podocarps, ferns and mosses were settling in, a plant revolution was brewing behind them. A new class of diverse and colourful plants was on the rise in Gondwanathe angiosperms, or flowering plants. Today, the angiosperms are the world's dominant plants, with 240,000 or more living species, compared to less than 600 gymnosperm species and about 10,000 ferns. With bright flowers, sweet nectar, aromatic scents and easily dispersed pollen and seeds, the angiosperms enlisted insects and wind as pollinating agents. From their origins, perhaps 250 million years ago, the angiosperm ancestors remained an obscure branch of the plant kingdom until about 130 million years ago when they gave rise to the first small flowering herbs and provided an evolutionary springboard for the pollinating insects (Crane et al., 1995). Within the past 100 million years, these plants diversified into herbs and shrubs, hardwood trees, grasses, palms and flaxes. Some made their way to New Zealand just before it parted company with Gondwana. Others arrived later.
Among the first angiosperms to reach New Zealand was the wind-pollinated southern beech tree (Nothofagus species). It arrived between 80 and 110 million years ago, after New Zealand had separated from the Australian part of Gondwana, but before it had separated from the Antarctic region. For several million years, the beech forests stretched continuously from Tasmania, and through what is now New Zealand and Marie Byrd Land in Antarctica, on into South America. Even today, the beech forests of New Zealand and South America resemble each other so closely that each has the same parasitic fungi, mosses and flightless sucking bugs inhabiting their bark (Stevens et al., 1995). While angiosperms were to displace gymnosperms in many parts of the world, New Zealand's gymnosperms and beech forests reached an ecological accord of sorts. The beech tended to occupy the cooler south and the high ground, while the gymnosperms took the north (i.e. the kauri forests) and the lowlands both north and south (i.e. the podoarp forests). In many intermediate zones, beech and podocarp formed mixed forests. They were later joined by other flowering trees whose seeds blew or floated down from westward and northern landmasses.
The beech trees were not the only angiosperms to migrate overland. The Magnolia, Protea, and Fuchsia families were others to arrive before the final split with Gondwana. After the split though, angiosperm immigrants arrived as pollen and seed on westerly winds and tides, or as passengers aboard windblown insects and birds. The ancestors of the pohutukawa and rata trees arrived this way some time after the great extinctions of 65 million years ago. They mingled with the podocarps and beeches and, in places, formed dominant red-flowered canopies of their own. Nikau palm arrived less than 50 million years ago as New Zealand was sinking, and the small trees Coprosma and Pittosporum got here less than 40 million years ago as the land became a string of islands. During this island phase many plants were probably lost, while those that survived began to evolve into slightly different species on each island. When New Zealand began rising again, about 25 million years ago, the land connections between these island species were restored, allowing a variety of closely related shrubs and trees to recolonise the land.
New species continued to arrive on the westerly air currents as New Zealand got bigger. They included the cabbage trees (Cordyline spp.) which landed here less than 25 million years ago, and the small herbs, such as daisies and rosette plants, which became established in the newly uplifted alpine areas less than 6 million years ago. Subsequent ice ages separated many populations into ice locked 'islands', once again leading to the evolution of separate, but closely related, alpine taxa. As a result, there are now more types of alpine plants than forest ones, though many of these are sub-species rather than full species. The last ice age ended about 12,000 years ago, and the plant communities that survived are a unique mix of the very old (e.g. mosses, ferns, kauri, podocarp and beech trees) and the comparatively young (e.g. cabbage trees, alpine herbs and tussock grasses). In human terms, of course, they are all ancient, having lived in stable and unique ecological communities for thousands of years before our arrival.
|Taxonomic Name||Common Name/Description||DoC (A and O species)||NZBS (Top 20)|
|Acaena rorida||Ruahine bidibidi; (piripiri)||T||T|
|Amphibromus fluitans||Water brome||T *||T *|
|Anogramma leptophylla||Jersey fern||T *|
|Asplenium pauperequitum||Poor Knights spleenwort||T||T|
|Atriplex billardierei agg.||Crystal wort||T *|
|Australopyrum calcis subsp. calcis||Limestone wheatgrass||T||T|
|Australopyrum calcis subsp. optatum||Limestone wheatgrass||T|
|Botrychium aff. lunaria||Moonwort||T|
|Caleana minor||Small or Flying duck orchid||T *||T **|
|Calochius herbaceus||Bearded swamp orchid||T *|
|Calystegia marginata||Australian bindweed||T *|
|Carex inopinata||a leafy, mat-forming sedge||T|
|Carmichaelia kirkii s. lat.||Kirk's native broom||T|
|Chiloglottis validus||Bird orchid||T *|
|Chordospartium muritai||Coastal tree broom|| |
|Christella dentata 'N.Z.'||Soft fern||T|
|Clianthus puniceus||Kakabeak; (kowhai gnutu-kaka)||T|
|Coprosma 'violacea'||a swamp coprosma||T|
|Cortaderia turbaria||Chatham Island toetoe||T||T|
|Corybas carsei||Swamp helmet orchid||T||T|
|Cryptostylus subulata||Duck orchid||T *|
|Cyclosorus interruptus||a thermal swamp fern||T *|
|Dactylanthus taylorii||Woodrose; (pua o te reinga)||T|
|Davallia 'Puketi'||Puketi hare's foot fern||T|
|Doodia aspera||Creeping rasp fern||T *|
|Gratiola nana||a low creeping herb||T *|
|Hebe bishopiana||Waitakere rock hebe||T|
|Hebe breviracemosa||Kermadec koromiko||T||T|
|Helichrysum dimorphum||a small shrub or scrambling liana||T|
|Hibiscus diversifolius||Thorny hibiscus||T *|
|Korthalsella salicornioides||Dwarf scrub mistletoe||T *|
|Lepidium banksii||Coastal peppercress(a stout herb)||T||T|
|Lepidium sisymbrioides subsp. kawarau||Kawarau Gorge cress||T|
|Lepidium sisymbrioides subsp. matau||Alexandra cress||T||T|
|Leptinella nana||Pygmy button daisy (Cotula)||T|
|Lepturus repens||Sickle grass||T *||T *|
|Marrattia salicina||King fern||T *|
|Melicytis 'Egmont'||A low-growing divaricating shrub||T|
|Metrosideros bartlettii||Bartlett's rata||T|
|Muehlenbeckia astonii||Shrubby tororaro||T|
|Myosotis 'Lytteltonensis'||a forget-me-not||T|
|Olearia hectorii||Hector's tree daisy||T|
|Olearia pachyphylla||Thick-leaved tree daisy||T|
|Ophioglossum petiolatum||Adders-tongue fern||T *|
|Pennantia baylisiana||a small tree up to 5 m tall||T||T|
|Peperomia leptostachya||Pacific pepperonia||T *||T *|
|Phylloglossum drummondii||a fern ally||T *|
|Pittosporum 'Surville'||North Cape kohuhu||T|
|Plantago spathulata subsp. picta||Papa plantain||T|
|Plectranthus parviflorus||Cockspur flower||T *|
|Pomaderris apetala||Tainui tree||T *|
|Pomaderris polifolia||a low shrub||T *|
|Pterostylis micromega||Swamp greenhood; (tutukiwi)||T|
|Pterostylis puberula||a greenhood||T||T|
|Pterostylis tasmanica||Plumed greenhood||T *|
|Ranunculus recens||'Moawhango' a buttercup||T||T|
|Sebaea ovata||a yellow-flowered annual herb||T||T **|
|Tecomanthe speciosa||Tecomanthe (a woody liana)||T||T|
|Thelymitra malvina||Kauri swamp sun orchid||T *|
|Thelymitra matthewsii||Spiral sun orchid||T||T *|
|Todea barbara||Royal fern||T *|
|Triglochin palustris||Marsh arrowgrass||T *|
|'X. it'||a lone small shrub, genus unknown||T||T|
DOC = Highly threatened plants in the Department of Conservation (1994b) Threatened Species Priority Lists A and O
NZBS = The top 20 plants on the New Zealand Botanical Society's Threatened Plants List (Cameron et al., 1995)
* Indigenous to New Zealand, but also has natural populations overseas that are not considered threatened.
** Indigenous to New Zealand and EITHER has natural populations overseas that are considered threatened
OR is thought to have natural populations overseas, but may, on revision, prove to be endemic to New Zealand.
Table 9.6: New Zealand plants which have not been seen for a number of years and may be extinct (X).
|Taxonomic Name||Common Name/Description||DoC (A and O species)||NZBS (Top 20)|
|Chiloglottis formicifera||Ant orchid||X||X *|
|Deyeuxia 'Flaxbourne'||an oat grass||X||Unlisted|
|Lepidium obtusatum s. str.||Scurvy grass||X||X|
|Lepidium obtusatum subsp. 'Manukau'||Scurvy grass||Unlisted||X|
|Leptinella filiformis||a button daisy (Cotula)||X||Unlisted|
|Logania depressa||a prostrate shrub||X||X|
|Muellerina celastroides||a mistletoe||Unlisted||X *|
|Myosotis laingii||Laing's forget-me-not||X||X|
|Pseudognaphalium 'Zoo'||Cud weed||X||Unlisted|
|Stellaria elatinoides||Native chickweed||X||X|
|Trilepidia adamsii||Adams' mistletoe||X||X|
DOC = Department of Conservation (1994b) Threatened Species Priority List, Category X
NZBS = New Zealand Botanical Society Threatened Plants List (Cameron et al., 1995)
* Indigenous to New Zealand, but also found naturally overseas where it is not considered threatened.
|Extinct||Critical||Endangered||Vulnerable||Rare||Insufficient knowledge||Total||Change 1989-95|
|Rocky shorelines and stony beaches||2||2||4||5||9||1||23||(+18)|
|Coastal cliffs and steep coastal slopes (including those with low scrub)||0||2||6||5||8||0||21|
|Coastal and lowland forest and tall scrub||2||3||6||7||8||2||28|
|Grasslands, herbfields and dry marshland||2||1||3||9||12||6||33||(+21)|
|Inland cliffs and rock outcrops||0||0||0||9||15||8||32||(+27)|
|Swamps, bogs, seepages||2||3||1||10||12||8||36||(+14)|
|Lake margins and aquatic habitats||0||2||2||3||4||0||11||(+4)|
Source: Wilson and Given (1989) updated by Given
New Zealand has a greater variety of mosses and liverworts than many comparable land areas around the world. Like the lowly fungi and flatworms, and the land snails and spiders, they are among our unsung biodiversity heroes - and our least known. For 400 million years, the mosses, liverworts, and their kin have lived in the shadow of the vascular plants. They have carpeted damp forest floors, clothed the decaying forms of fallen logs and colonised bare rock surfaces in the aftermath of volcanic eruptions, landslides, or other disturbances. They are as comfortable by the seaside as they are clinging tenaciously to icy wind-blasted scree on the highest peaks. Though overshadowed, they have survived longer than any of the species that now share the forests and rock faces with them. Indeed, it is their survival techniques which allow other, more showy plants, to become established where soil is thin or bare. The nursery 'bed' they provide for seeds helps to prevent soil erosion and harbours a wealth of tiny invertebrate animal life.
Today New Zealand has about 1,070 species of this ancient plant grouping. Collectively they are known as Bryophytes, a plant division (or phylum) with five classes: true mosses (Bryopsida), granite mosses (Andreaeopsida), peat mosses (Sphagnopsida), liverworts (Hepaticopsida) and hornworts (Anthocerotopsida). New Zealand's species are divided roughly equally between the mosses and the liverworts. Hornworts contribute just 26 known species to the total.
The Department of Conservation lists 85 mosses and liverworts as threatened - 8 percent of our known bryophyte species. As testimony to their rarity and anonymity, all the threatened species have only Latin names. Most of them (51 species) are listed in the Department of Conservation's Category I, which contains species that are threatened but not known well enough to be ranked (Department of Conservation, 1994b). Of the 34 species known well enough to be ranked, 6 are in the top category - 3 mosses and 3 liverworts. One of these is Schistochila nitidissima, an extremely rare liverwort restricted to the Waipoua Forest. It is semi-aquatic and grows on rocks near the water. If the forest had not been protected as a reserve for kauri trees 40 years ago, this hapless liverwort may have become extinct before anyone even knew of its existence.
|Habitat type||Percentage of our threatened plants coming from each habitat|
|Moss or Liverwort||Description and Habitat||Location|
|Archidium elatum||A black moss which grows in dense carpets, mainly on coastal rocks.||Three known locations: near Rotorua, the Bay of Islands; and Northland.|
|Fissidens berteroi||A soft green moss growing in flowing water.||Four known locations: 2 near Lake Wairarapa, and 2 in suburban Auckland.|
|Lindbergia maritima||A creeping brown moss which grows on coastal rocks.||Near Auckland.|
|Chloranthelia berggrenii||A greyish-green liverwort forming a turf on natural and roadside banks.||Known at sites in Dunedin, Mt Cook, Arthur's Pass, and West Waikato.|
|Pachyschistochila papillifera||A soft, clear green liverwort growing in soil on limestone ridges.||Alpine areas of the Ruahine Range.|
|Schistochila nitidissima||A pale green liverwort forming patches or cushions on soft rocks in streams.||The Waipoua and Puketi Kauri Forests, Northland.|
Among the most threatened mosses is the endemic Archidium elatum, which grows mainly on coastal rocks. It is known from only three localities, one in the Rotorua area, one in the Bay of Islands, and the third in Northland, but since the plants are very unobtrusive, it may be more common than realised. Lindbergia maritima, which also features in Category A of the Department of Conservation's threatened species list, is known from only one location, near Auckland. It was discovered by an overseas botanist a little over 10 years ago. Another species known from only one location is Epipterygium opararense, which is one of the 51 species listed in Category I. This endemic moss was found clinging to the side of granite boulders in the Oparara Reserve in north-west Nelson.
Another moss fighting for survival is Fissidens berteroi , whose aquatic habitat and bright-green, soft, lax foliage distinguish it from other related Fissidens species in New Zealand. A century ago this attractive moss was known from scattered sites throughout the country. Now it is known from only four sites: two near Lake Wairarapa and two in the suburbs of Auckland. The 1994 Auckland water crisis almost killed off the population at one of these sites, when water stopped flowing in the drain where the moss lives, leaving just a puddle. Only quick action by botanists saved the moss. Although Fissidens berteroi is known overseas, it is not common and its extinction here would be a loss of international significance.
Of all the mosses, only one has caught the attention of the commercial world, sphagnum moss. New Zealand has 11 species of sphagnum, but Sphagnum cristatum is the most common and the species best known to the public, particularly home gardeners. This remarkable plant has antibacterial properties and the ability to absorb and retain up to 20 times its own weight in water. Sphagnum forms extensive carpets or hummocky cushions in the squelchy, rain-soaked forests of the South Island's West Coast and in Southland. It is thought to play an important role in the storage and flow of water in upland catchment areas.
Horticulturists have found sphagnum to be an ideal growing medium, particularly for orchids. Sphagnum harvesting on the South Island West Coast and in Southland has become an enormously profitable export industry providing part-time work for several hundred people, or the equivalent of about 180 full-time jobs, while earning up to $18 million per year (Tilling, 1995; Orchard, 1994). Licences are granted to collect the moss from areas which have been logged or mined. Most of it comes from Department of Conservation land with low conservation value. Two other sphagnum species, one in Otago and one in the northern North Island, are considered threatened, but their conservation priority cannot be assessed because so little is known about them (Department of Conservation, 1994b).
Disturbance and habitat loss are the greatest threats to the mosses, liverworts, and hornworts, but the effects of collecting and even trampling cannot be overlooked. Any activity which results in the drying out of a habitat will almost certainly cause the death of wetland species. The loss of 85 percent of New Zealand's wetlands in the past century may well have eliminated several species whose existence was unknown and will remain unrecorded.
The very nature of mosses, liverworts and hornworts makes it difficult for botanists to say with certainty that any particular plant or colony may be the only one in existence. Even the excitement of new discoveries is mixed with concern. Botanists recently found several new species in Northland and on Mount Ruapehu. They may even be new to science, not just to New Zealand. The anxiety comes from the fact that the new species are known only from single collections, and must be regarded as very rare, even threatened, until more is known about their relationships and distribution. One thing scientists can say with certainty: some species are so fussy about where they grow that they have limited options for their continued existence.
About 2,000 species of native vascular plant species have been formally described and named, and 200-300 more plants are awaiting formal identification. If subspecies are included, the total number of vascular plant taxa may be 2,500 or more (Department of Conservation, 1994b; Druce, 1984; Halloy, 1995; Statistics New Zealand, 1995). Though our vascular plant biodiversity is low by international standards, its endemism is high. About 80 percent of our vascular plants occur nowhere else on Earth and are therefore of global as well as local significance (Wilson and Given, 1989; Dawson, 1988). Our most diverse plant communities are also the youngest. The alpine zone has more plant taxa for its small area than other ecosystems, such as forests and wetlands, abounding with small populations of flowering shrubs, cushion plants and grasses. The forests have fewer species, but greater phyletic diversity, with bryophytes, ferns, gymnosperms and flowering plants living in mixed communities.
Although the demand for native timber, particularly rimu, kauri, and kahikatea, and the conversion of land to pasture, have reduced the original forest cover from about 85 percent to about 23 percent, none of New Zealand's unique timber-producing trees has been reduced to threatened status. Most of New Zealand's threatened plant species are small herbs, grasses and shrubs with limited distributions. In total, nearly 200 species and 20 sub-species of vascular plants are listed as threatened by Department of Conservation. This amounts to almost 10 percent of our native vascular plants, though close to half of these are in the 'insufficiently known' category (Department of Conservation, 1994b).
Several of the threatened plants are very small, such as the highly threatened woodrose (Dactylanthus taylorii), which is known to Māori as pua o te reinga (flower of the Underworld) and is prized as a curio (Dawson, 1988). This 'Category A' species lives as a parasite on the roots of small trees, often in fire-induced secondary forest, in the North Island (Ecroyd, 1996). It is pollinated by a rare native bat. The reddish brown scaly flowers of the Dactylanthus protrude directly from the earth while the body of the plant remains underground. The flowers have a strong sweet perfume, which is attractive to flies and native bats. Unfortunately, the Dactylanthus scent also attracts possums and rats. The survival of the woodrose will require protection of the plants from possums, rats and humans, and will also need adequate areas of secondary forest with abundant hosts.
Some of our most seriously threatened plants are found on offshore islands. Among them is Hebe breviracemosa. This shrub, which grows to a height of about 2 m, is found only in the Kermadec Islands. It once flourished on the main island, Raoul, but it was almost eaten out of existence by feral goats released last century and, for many years, was considered extinct. It was believed the last known specimens had been collected in 1908, but in 1983 one plant was found on Raoul Island. The last goat was taken from the island in November 1984, and it is hoped that H. breviracemosawill become re-established (Wilson and Given, 1989). One remaining threat is the continued presence of Pacific rats on the island. They are suspected of nibbling away any seedlings that come up.
Slightly better off, but still on the critical list, is the Swamp Helmet Orchid (Corybas carsei) so named because its flowers are tubular helmet-like structures. This plant has only been found in acid peat bogs of the northern North Island. Originally discovered in the large peat bogs bordering Kaitaia during the early 1900s, drainage operations had eliminated it there by the 1920s. During the 1960s, it was discovered in some abundance within the Moanatuatua Peat Bog near Ohaupo in the Waikato. Its discovery prompted the formation of the country's first large peat bog reserve. Unfortunately, the bog proved to be too small, and peripheral draining caused the peat vegetation to thicken.
Today, the Swamp Helmet Orchid survives in part of the Whangamarino Wetlands, where hundreds of the tiny orchid plants were recorded in the early 1980s. In October 1991, only 30 plants were recorded. Only one flower has been recorded since 1991, and this failed to set seed. It is now believed that the Swamp Helmet Orchid lacks a suitable pollen distributor, while bud predation by an introduced species of cricket remains a serious threat to the plant's reproductive potential. The survival of the species depends on careful management of the peat vegetation at the site through controlled fires.
The remote Three Kings Islands group off the tip of the North Island was one of the first places where management action was taken to save plants from extinction (Wilson and Given, 1989; Templeton, 1994). In 1946, two plants, both new to science, were discovered there: a vine with beautiful tubular cream flowers, named Tecomanthe speciosa, and a small tree with large lush dark-green foliage, called Pennantia baylisiana.
The island's feral goats had pushed the plants to the verge of extinction. Although the goats were eradicated in 1946, neither the vine nor the tree has recovered. Fortunately the vine's seeds and cuttings have been easy to cultivate. Thousands of plants are grown each year and sold to gardeners throughout the warmer parts of New Zealand and overseas. Soon the vine may be listed as extinct in the wild even as its numbers increase in people's back yards. The situation with the tree is not so encouraging because the sole plant is a female and therefore incapable of producing seed (unlike the vine which can produce male and female flowers, and therefore seeds).
One species not on the threatened list, but which has been the subject of some concern since 1987, is a cabbage tree, ti kouka ( Cordyline australis). In the warm, upper North Island 1530 percent of these trees have died and are continuing to do so. A smaller percentage of trees are dying in the southern North Island but almost none in the South Island (Brockie, 1995), though some anecdotal evidence suggested an earlier die-off in parts of Canterbury (Hosking and Hutcheson, 1992).
Death appears to be caused by an infection, but the dying trees are out in the open, while the survivors are in areas of native forest. The pattern of infection seems to coincide with the distribution of an introduced insect, the sap-sucking Australian passion-vine hopper (Scolypopa australis), which is most abundant in the warm northern regions away from dense forest. If the link is confirmed, little can be done other than to wait for the wave of infection to pass and hope that an infection-resistant generation will arise from the survivors (Brockie, 1995).
Many of the plants which are culturally important to New Zealanders of European, Asian or Pacific Island origin are exotic species and are not threatened. To New Zealanders of Māori origin, however, the culturally significant plants are mostly native species, together with a small number of exotics that were introduced many centuries ago. Some of these plants are in short supply, either because they have become rare or because they are on land which is no longer in Māori ownership. The ecological, social and economic changes of the past two centuries have dramatically changed the relationship between Māori society and plants. Today the culturally significant plants are no longer necessary for survival, but they are important for traditional arts and crafts, customary food preparation and herbal remedies. Some are now largely confined to Department of Conservation land or to collections managed by Landcare Research. Others are more widespread, but are under pressure.
The Department of Conservation (1994b) lists 18 culturally important plants that have become rare in at least some iwi areas, though several are still common nationally. They include five species introduced by early Māori settlers: aute or paper mulberry (Broussonetia papyrifera) which was cultivated for bark-cloth; hue or bottlegourd (Lagenaria vulgaris), which provided food and water containers; and the staple food plants, kumara or sweet potato (Ipomoea batatas); taro ( Colocasia esculenta); and uwhi or yam (Dioscorea sativa). Indigenous species which are culturally important and listed as locally or nationally rare include: harakeke ( Phormium tenax); pingao (Desmoschoenus spiralis); kiekie (Freycinetia baueriana banksii); totara ( Podocarpus totara); aruhe or bracken fern (Pteridium esculentum); wharariki or mountain flax (Phormium cookianum); karaka (Coryncarpus laevigatus); kutakuta (Eleocharis sphacelata); para or king fern (Maratia salicina); the rush-like herb Sporadanthus traversii ; tawapou (Planchonella costata); and two endemic cabbage trees, ti pore (Cordyline fruticosa) and ti tawhiti ( Cordyline 'kirkii').
Traditional Māori uses of native plants were varied and ingenious and several are still a vibrant part of Māori cultural life, particularly harakeke flax and pingao grass, and totara and other trees which are used in carving. Plants were also used to make dyes, rope, fishing lines and nets, bird snares and cloaks and blankets. Logs were used to make canoes, buildings and fortifications. Rushes, supplejack and nikau leaves were used in thatching. And, after European contact, the medicinal use of plants became significant. The native plants' only limitation was their food value. Although some 300 New Zealand plants are edible (Crowe, 1990), most are poor sources of sustenance because their roots and berries are too small or unpalatable to provide large amounts of carbohydrate (starches, sugars and oils).
Wherever the climate allowed (mainly in the north of the North Island) Māori communities relied on five imported tropical plants for carbohydrates: kumara; taro; uwhi (yams); hue (bottlegourds); and a cultivated species of ti or cabbage tree (Cordyline terminalis). Elsewhere, however, the main sources of carbohydrates were the barely edible rhizomes of the native aruhe or bracken fern (Pteridium esculentum) and the sugary roots of several endemic cabbage trees (Cordylinespp.).
Although many other plants were eaten, few made big contributions to the diet of meat, fish, kumara and fern-root. Despite this, some native plants are still sought after today, such as the young green shoots of the pikopiko fern (Polystichum richardii), the soft heart of the nikau palm trunk ( Rhopalostylis sapida), and berries from various trees, notably tawa and karaka (which require cooking to detoxify them). ). Among the popular traditional vegetables that are commercially cultivated today are two sow thistles (Sonchus asper and S. oleraceus), known as puha and rauriki (Crowe, 1990; Wardle, 1994). These were introduced as weeds by early Europeans and have spread widely at the expense of the larger but slower growing native sow thistle (Sonchus kirkii) which is now rare. Though not plants, native fungi (e.g. harone or mushrooms) and algae (e.g. rimurapa or bull kelp) are also still eaten (Cooper and Cambie, 1991; Crowe, 1990; Gluckman, 1976; Walls, 1988).
With European contact came edible vegetables, such as potatoes, maize, wheat, turnips and cabbages, and edible weeds, such as toi, a kind of cress (Barbarea spp.), huainanga or fat hen ( Chenopodium album), and several wild Brassica species (Crowe, 1990). The new vegetables also included European varieties of kumara whose vines could grow up to 5 m compared to a maximum vine length of 1.4 m for the local varieties. The Māori kumara would have been lost were it not for the efforts of a DSIR scientist, Dr Douglas Yen, who painstakingly assembled a collection of 617 kumara varieties from all over the world during the 1950s and 1960s. In 1963, when the collection became too big for the DSIR to maintain, Dr Yen arranged for its safekeeping in three gene banks in Japan. Interest in the collection was revived in 1988 at an ethnobotanical conference organised by the DSIR. Members of Pu Hao Rangi, a Manukau-based Māori Resource Centre, journeyed to Japan and brought back 9 New Zealand kumara varieties, 4 of which were identified as pre-European varieties. These are now cultivated by several Māori groups.
The most enduring traditional use of native plants has been in weaving and carving, which were developed to a high art and are still important, especially in the upper North Island. The favoured weaving plants are harakeke flax, pingao, toetoe or kakaho, and kiekie, and the favoured carving trees are totara (Podocarpus totara) and kauri (Agathis australis). The traditional experts on weaving were, and still are, women whose specialist knowledge gives them considerable mana (prestige). Each weaving family has its own traditional account of the origin and appropriate use of the local plants. As a result, these plants have acquired a large number of different names, uses and harvesting methods, each associated with a particular place and tradition.
The most useful all-round plant was harakeke (flax). Many families tended their own stands. Its sap was used to treat constipation and wounds, its nectar sweetened the diet of fern root, and its fibres were used to make baskets, mats, sandals, clothing, ropes, cords, fishing lines, nets, traps, children's kites and trumpets. The diversity of uses and local varieties gave rise to some 80 different names for harakeke and made it a valuable item of inter-tribal trade. Its tradeability increased following European contact. Dressed flax was exported for rope-making and whole families became involved in production for export. It was labour intensive; 40 tonnes of hand-scraped flax produced one tonne of fibrethe price of two muskets. In the 1820s flax exports funded most of the arms used in the inter-tribal wars, but Māori interest waned and the trade had almost ended by the 1850s, though traditional use continued (Department of Statistics, 1990; Douglas, 1993).
Exports were revived in the 1860s when the American Civil War caused a temporary world shortage of manila and sisal fibre. By now, control of the industry had passed to European entrepreneurs who introduced machine processing. With production no longer dependent on Māori knowledge and labour, flax was harvested ruthlessly and output increased 100-fold in the decade 186373. At the boom's peak more than 300 mills operated. By 1886, however, only 30 mills remained. The second boom coincided with the Spanish-American War (189091) and the number of mills rose to 177. The third and last harakeke boom was triggered by the First World War (191418) and lasted into the late 1920s. Production for the local market continued for four more decades, finally ending in the late 1960s (Department of Statistics, 1990).
Although flax is still widespread, relatively few large stands remain. Most of the wetlands where they flourished have been drained and replaced by pasture. Apart from a brief expansion in the mid-1920s, when several thousand hectares of harakeke were planted, the total area fell from about 25,400 hectares in 1929 to about 16,000 hectares by 1960 (Douglas, 1993; Department of Statistics, 1970). It is probably less today. Cultural users of harakeke are fortunate to have a national collection of 68 traditional varieties collated by the former DSIR, mainly from the collection of Mrs Rene Orchiston of Gisborne. The collection is located at Havelock North and Lincoln, and daughter collections have been distributed to marae in other areas.
The sand dune plant, pingao, is another culturally important species which has become rare in many areas. Its stiff, curled, three-ridged, leaves are used for weaving and for making the tukutuku panelling which lines the walls of marae. The leaves range in colour from green to golden-yellow. On the beach, pingao clumps look like separate plants, but they are usually offshoots of a single underground rhizome which forms a delicate lifeline in the sand. Pingao was never commercially harvested or planted. It has been reduced by a range of pressures that affect our dunelandsgrazing, the spread of exotic dune plants (e.g. marram grass and lupins), urban development and trail bikes and dune buggies. Harvesting pressure is now adding to these pressures.
As with harakeke, the use of pingao has greatly increased. This has intensified pressure on the diminishing stocks of wild pingao. In the past, the harvesting and use of pingao (and other important plants) was governed by strict rules, or tikanga Māori, designed to maintain the plants. Often rahui (temporary bans) were put on areas that were becoming depleted. The traditional weavers were steeped in knowledge of how and when to harvest the plants. They would size the strands and assess their condition before cutting began. Few have this knowledge today. Without the correct tikanga, indiscriminate pingao harvesting has occurred in many places. A survey of the Manawatu dunelands found pingao throughout, but often at densities of only one plant or clump for every 20 m (Carkeek, 1989; Turoa et al., 1990).
Although the most visible use of culturally significant plants is in arts and crafts, a greater variety of plants is used in Māori herbal medicine, or rongoa. This tradition is historically recent, dating largely from the nineteenth century, but it plays a significant role in contemporary Māori culture and has elevated the cultural significance of many native plants.
Before European contact, Māori society, like the rest of Polynesia, made only limited use of plant-based treatments, mainly because disease was believed to have spiritual causes, such as retribution for violating tapu (sacred rules). In James Cook's three Pacific voyages between 1769 and 1779, he found little evidence of plants being used for internal medication, despite their use in external treatments and healing rituals. For the next half-century, other European explorers, sailors and missionaries reported similar observations. External plant treatments were confined to visible ailments and injuries and included: leaf wrappings, ointments and poultices (to reduce bleeding, pain and inflammation); fern ashes (to treat burns); splints of flax leaves or rata bark (to mend fractures); and scented steam baths made by placing leaf mats on hot stones. The few plant remedies that were swallowed seem to have been cathartics for constipation, and possibly emetics to induce vomiting (Buck/Hiroa, 1949; Brooker et al., 1987; Cooper and Cambie, 1991; Whistler, 1992).
The standard treatment for internal ailments was not medicine but a healing ritual presided over by a priest or tohunga. The key elements were prayers and confessions, sometimes accompanied by human or animal sacrifice. Plants were sometimes used to repel demons either intact, shredded, or in fetid-smelling potions (Buck/Hiroa, 1949; Brooker et al., 1987; Cooper and Cambie, 1991; Whistler, 1992). By 1820, Polynesian experimentation with herbal remedies was well under way, partly in response to the example set by European medicines, and partly in response to the wave of European diseases for which there were no traditional cures. Māori use of herbal medicine for internal complaints was first noted in the 1820s and by 1900 more than 100 native plants were in medicinal use (e.g. Williams, 1826; Lesson, 1829; Bennett, 1834; Goldie, 1905).
While most of these plants, from a pharmacological viewpoint, "could at best have no great medicinal value", some are now known to have antibiotic, analgesic or astringent properties (Brooker et al., 1987). Several were poisonous (e.g. tutu, kowhai, puketea, horopito, poroporo and karaka) resulting in remedies that occasionally killed rather than cured (Brooker et al, 1987). Among the more effective plants are: various Hebe species (e.g. koromiko) which inhibit the bowel contractions in diarrhoea; harakeke, which is used as both a laxative and an anti-inflammatory treatment for wounds and burns; kakaho or toetoe (Cortaderia toetoe) which also has anti-inflammatory uses; pate or seven-finger (Schefflera digitata), whose fungicidal compounds are effective against ringworm; manuka (Leptospermum soparium), which has insecticidal and anti-bacterial properties, though it is more often consumed as a general tonic; and several plants with analgesic properties, such as kawakawa ( Macropiper excelsum), the fern Asplenium lamprophyllum, and the poisonous plants, pukatea (Laurelia novae-zelandiae) and horopito or Māori painkiller ( Pseudowintera axillaris). Horopito bark juice is used for a variety of painful conditions, ranging from stomach-aches to skin and venereal diseases (Cooper and Cambie, 1991; Brooker et al., 1987).
For many other plant remedies the effects appear to be more subjective. Kumarahou (Pomaderris kumarahou), for instance, acquired a reputation as a commercial cure-all last century, and is still used as a general panacea, despite its lack of medically active compounds (Cooper and Cambie, 1991; Health Research Council of New Zealand, 1994). The bark juice from kowhai (Sophoraspp.) was used to treat constipation, ringworm and scabies, but it had to be from a tree growing on a hillside and a root pointing towards the sun (Cooper and Cambie, 1991; Brookeret al., 1987). Despite the improvements in conventional medicine, herbal remedies have persisted and diversified since 1900. Like other forms of alternative medicine, they may even be expanding as conventional medical treatment becomes more costly. About 44 Lotto-supported rongoa clinics now operate throughout the country, and the list of recorded native medicinal plants is now more than 200 (Health Research Council of New Zealand, 1994; Riley, 1994).
Environmentally, the main significance of the rongoa movement is that it enlarges the pool of culturally important plants which need to be sustainably managed. In many areas these are now confined to land managed by the Department of Conservation and can only be harvested with the Department's permission. Although this is usually forthcoming, many iwi would like more control over customary plant use in their areas, particularly where non-iwi members and bioprospectors are also seeking permission to harvest them. Some Māori have even lodged a claim with the Waitangi Tribunal (Claim Wai-262) seeking iwi control over all indigenous biodiversity (Murray et al., 1991). The need to sustain culturally significant resources is recognised in our environmental legislation, and the challenge is to develop management regimes which will safeguard cultural use rights and traditional knowledge while also maintaining the plants for their intrinsic and ecological values and the benefit of society in general (Geden and Ryan, 1995; New Zealand Conservation Authority, 1994; New Zealand Ecological Society, 1995; Te Puni Kokiri/Ministry for Māori Development, 1994; Thrush, 1995; Wright et al., 1995).
The Fungus kingdom is the most diverse and numerous kingdom of organisms after the animals. Fungi occur almost everywhere, provided there is moisture and a nutrient source for them. Estimates of the number of known species range from about 70,000 to more than 100,000. If unknown species are estimated as well, the world total comes to a possible 1.5 million fungal species (Kendrick, 1994; Hawksworth et al., 1995).
With an estimated 20,000 species here, fungi may represent more than a third of New Zealand's total biodiversity. Their most important role in our ecosystems is as humble, but vital, decomposers and nutrient recyclers. Without them, 9 out of 10 of our plants would disappear, and so would the animals that depend on them.
Traditionally, fungi have been regarded as closely related to plants, but recent genetic research suggests they are closer to animals (see Figure 9.1) (Wainright et al., 1993). Apart from genetic differences, the fungi differ fundamentally from plants in having no chloroplasts and no ability to produce their food by photosynthesis. However, they differ from animals too, having no mouths or digestive organs with which to eat food, nor excretory organs to remove waste.
As it happens, the fungi do not need these complicated accessories because they get their food by a remarkably effective technique which does not involve internal digestion or waste products - they directly absorb it through their cell walls. They do this by exuding powerful digestive juices onto a plant or animal. As the organism begins to decompose, the fungi absorbs its nutrients directly from the decaying matter. The unwanted bits are left to rot into the soil. This minimalist approach to body design extends to nervous systems, sense organs, muscles and limbs, none of which are needed by fungi because they do not get about much. A fungus does all its travelling, courtesy of wind and running water, when it is still a tiny spore. Once it has landed on a potential food organism, the spore attaches and begins to develop into a mature fungus. The only organs the adult needs are reproductive organs to produce more spores.
The true fungi (or Eumycotes) are mostly multi-celled (except for yeasts). They range from microscopic threads, through shapeless moulds, to rounded puffballs and truffles, to beautifully sculpted mushrooms and toadstools. They are not related to the false fungi (or Myxomycotes) which are amoeboid slime moulds - protozoans that merge together for part of their life cycle. A fungus holds the record for the world's largest living creature. This unlikely giant, which is believed to be between 500 and 1,000 years old, extends, like a vast underground spider's web, beneath 600 hectares of pine forest in Washington State (Coghlan, 1992). It belongs to a species called the Honey or Shoestring Fungus (Armillaria ostoyae) which feeds by parasitising tree roots and reproduces by extending mushrooms up through the ground so that wind and rain can disperse its spores. The mushrooms of the shoestring fungus are edible, as are those of its New Zealand relative, the Bootlace Mushroom.
For most people, edible mushrooms are probably as interesting as fungi get. Many edible species exist in New Zealand, both introduced and native. More than 500 native mushrooms have been identified, though not all are edible. Some formed a small but prized part of the traditional Māori diet, and one species was used as tinder for fire lighting. The edible species which are popular today include the morel, the giant and common puffballs, the sticky bun and birch boletes, the fungus icicles, certain ink caps, the poplar mushroom, and the wood ear, which was exported to China in considerable quantities in the late 1800s.
The best known, and safest, edible mushrooms, however, are probably the introduced white button mushroom (Agaricus bisporus), which is grown commercially for the supermarket, and the white-topped field mushroom (Agaricus campestris) from the farmer's paddock. Other edible mushrooms now available at specialist food counters include shiitake (Lentinula edodes), oyster or Phoenix mushroom (Pleurotus pulmonarius), and needle mushroom (Flammulina velutipes). Even some fungal scientists (mycologists) will only eat shop-bought mushrooms because some species are highly poisonous and even the expert eye can be fooled by their similarity to harmless ones.
Poisonous mushrooms are often called 'toadstools'. Like many other fungi, they produce toxins, either for defence, or to kill potential food organisms. Particularly dangerous are two introduced members of the Amanita genus: the deadly yellow-brown Death Cap (Amanita phalloides), which is usually found near oak trees, and the red-topped white-speckled fly agaric (A. muscaria), which occurs more widely in moist shady areas. Poisoning can result simply from touching food or lips after handling these. The fly agaric gets its name from its potency as a fly killer when ground up and mixed with water. Children are particularly at risk from this toadstool because of its colourful appearance and because it often features in children's books, and even in a recent widely sold children's calendar.
Many fungi besides mushrooms have become part of our everyday life. Regular reminders range from foods such as cheeses and yoghurt, which are fermented by fungi, to the mould on the bathroom ceiling. The yeast fungi are used to bake bread, brew beer and ferment wine. Many people have been rescued from bacterial infections by the well-known antibiotic, penicillin, which is produced by a fungus called Penicillium notatum. Others owe their lives to cyclosporine, which is an immunosuppressant produced by a fungus called Tolypocladium inflatum. It reduces organ rejection in transplant patients.
Against these health-giving fungi are many which cause diseases. Athlete's foot and ringworm are two common fungal diseases afflicting humans, and Cryptococcus neoformans, a fungus associated with pigeon excreta, can cause a form of meningitis. In humid weather, sheep farmers are on the alert for signs ofPithomyces chartarum, which causes facial eczema. Fungi are the main agents of plant diseases too, affecting all plants, including commercially grown species. For example, a native species of Armillaria can kill kiwifruit vines and young pine trees. Fungi also invade harvested pine logs and orchard fruit, causing lost profits and high pesticide costs.
Fungi fall into two groups, depending on how they get their food. Some are parasitic, feeding off living organisms (e.g. the fungi which cause skin diseases in humans and other animals, and those which cause mildew and blight diseases in plants). Others are saprobic, dining off dead organic matter (e.g. yeasts and the various fungi which cause logs and timber to rot).
Many fungi form mutually beneficial relationships with plants. More than 90 percent of plants have symbiotic mycorrhizal fungi associated with their roots. The fungi appear to play a protective role against hostile fungi and invertebrates, and may also provide scarce nutrients such as phosphorus in return for carbohydrates from the plant's roots. Perhaps the most famous mycorrhizal species is the prized black truffle (Tuber melanosporum) which grows in association with oak trees. About 20 percent of fungi form lichens. Lichens are fungi that have algae living inside them. They appear as rather flat, crinkly growths on tree trunks, fence posts, rocks, boulders, buildings and even footpaths (where they sometimes look like splashes of pale green paint). They may even hang like shaggy grey-green beards from the branches of forest trees. They come in a range of colours from subdued greys and pale greens to bright yellows and rich browns. These colours do not come from the fungus itself, but from colonies of microscopic algae which live in or on its tissue. These algae make up 510 percent of the lichen biomass.
Just as the mycorrhizal fungi obtain carbohydrates from their symbiotic plants, so lichen fungi obtain carbohydrates from their symbiotic algae. Until recently the lichens were believed to be a closely knit fringe group of fungi. However, research now shows that unrelated lichens occur throughout the fungus family tree, indicating that the partnership between fungi and algae arose separately several times in fungus evolution (Gargas et al., 1995; Barinaga, 1995). The oldest known lichen fossil dates back 400 million years suggesting that they were an instrumental group in the early colonization of land and formation of soil (Tayloret al., 1995).
New Zealand has a particularly rich variety of lichens compared to other countries. At least 1,500 species have been described, representing about a third of our known fungi species. In the Northern Hemisphere, acid rain and air pollution are reducing lichen biodiversity. In New Zealand, lichens are still common. Even though their natural forest environments have been largely removed, many have found suitable niches in towns, on footpaths, buildings and fences.
Taxonomic studies of New Zealand fungi lag well behind those of animals and plants. Of our estimated 20,000 species, only about 4,500 are known. The difficulty of finding out how many species are rare or threatened is made worse by the fact that few New Zealanders collect fungi, and even fewer experts are able to identify them with certainty. However, based on assessments of groups which have been relatively widely collected and studied, Landcare Research scientists believe more than 200 identified fungi are threatened in New Zealand - about 5 percent of known species (Buchanan and Beever, 1995).
The main threat to most fungi has been habitat destruction. Being forest dwellers which coexist with trees in shady, damp environments, the fungi were among the less visible casualties of New Zealand's lowland deforestation. Some species probably vanished without ever being seen.
Rust fungi (Puccinia spp.) are microscopic parasitic fungi which typically form orange or rust-coloured pustules on plant leaves. One newly recognised endemic species is threatened because it lives only on the Chatham Island sow thistle (Embergeria grandifolia), which is itself a threatened species. Another vulnerable species is a large polypore fungus (Ganoderma spp.), which forms big shelf-like fruit bodies on tree trunks. This as yet unnamed species was recorded at three sites in Waikato from 1969-1972, but has not been seen for the past 24 years (Buchanan and Beever, 1995).
Yet another doubtful survivor is the endemic truffle-like fungus, Claustula fischeri. This is the only known member of the family Claustulaceae in the world. It has been identified from the Fringed Hill area in Nelson, and from one site in the Wairarapa. The careless harvesting of highly priced mushrooms, such as truffles, and the habitat disturbance which can result, is placing those species under pressure. Even collecting a fungus to study it professionally or as a hobby could unwittingly place a species under threat.
Landcare Research is compiling a comprehensive list of threatened New Zealand fungi similar to the 'red data' lists produced in countries such as the Netherlands (which has 944 threatened fungi), Sweden (which has 500) and Finland (which has 325). The first red data list for New Zealand fungi is based on information from herbarium collections and scientific papers (Buchanan and Beever, 1995).
|Aecidium spp. (3)||Rust; 2 endemic and 1 indigenous species.||Restricted distribution on Hebe spp. Two species not seen since the 1920s.|
|Claustula fischeri||Mycorrhizal, truffle-like fungus.||Nelson (Fringed Hill) and Wairarapa; under kanuka or manuka.|
|Ganoderma (new species)||Polypore bracket fungus with shiny upper surface.||On pukatea, in the vicinity of Mount Pirongia, 1969-1972. Not found since despite searches.|
|Grifola sp.||Multi-lobed, large, fleshy polypore, with strong odour of almonds from fruit body and wood rot.||On large, fallen rata, probably confined to old growth forest.|
|Gyromitra sp.||Large, stalked, brain-like ascomycete.||Recorded once, under Nothofagus.|
|Lanzia griseliniae||Micro-ascomycete.||On leaves ofGriselinia. Despite searches, only known from Ruapehu (1950s), and a single record at Karamea.|
|Perenniporia podocarpi||White crust-like polypore.||Known from only 4 records; on fallen branches of rimu and matai.|
|Puccinia sp.||Rust. An endemic plant pathogen.||On leaves of the threatened Embergeria, on the Chatham Islands.|
|Tympanella (new species)||Stalked mushroom, with or without closed cap.||Recorded once in NW Nelson under Nothofagus. Currently the genus is monotypic and confined to New Zealand.|
Source: Landcare Research