Fields of Gold
Wherever it is too dry, cold, wet or rocky for trees to prosper—as at Lake Heron, in inland Canterbury—expect to find tussock. It is as intrinsic to the high country as sand is to Ninety Mile Beach. But who should own and manage the tussock lands?
Upa little-used road in eastern Fiordland lies the site of the world’s largest onshore landslide. Thirteen thousand years ago, as the glaciers retreated, a mountain range collapsed, hurling 27 cubic kilometres of rubble into the valleys below. From Borland Saddle the land now drops in angular blocks and hummocks until it hits the valley floor, where it splays out tangled arms. Down there, webs of standing water transect a rippling carpet of red tussock, Chionochloa rubra.
Up on the saddle itself I am standing on dark peaty soil, amongst knee-high tussocks bedecked with tresses of green, olive and gold and with a tousled, blow-dried look. I’m helping Kelvin Lloyd, a scientist from Landcare Research, gather Chionochloa—the genus to which most of our tall tussocks belong—for his studies. He has pointed out a handful of different species en route and I have been doing my best to distinguish between them.
“What’s that one?” he asks, nodding at a tussock swooshing against my shins.
“I have no idea,” I admit sheepishly.
He points out a row of fine blond hairs running up each leaf. Of course, this is Chionochloa teretifolia—the hairy one! How could I forget so quickly?
I’m relieved when Kelvin tells me that even botanists find tussocks tricky to identify. Many Chionochloa species look very similar and hybridise where their ranges overlap. New species are still being defined—there may even be one on the gilded summit of nearby Mt Burns, although the jury is still out. And the Borland Saddle region is one of the few places in the country where half a dozen different species grow within waving distance of each other.
Despite the abundance of species here, the tall tussocks are mostly parochial, with distinct habitat preferences. For instance, red tussock thrives on waterlogged or frosty flats, C. conspicua occurs at forest margins, C. teretifolia prefers peat. Where conditions are favourable, one can often see great swathes of a single species billowing en masse. C. acicularis, the species with its fine bluish leaves that Lloyd is here to collect, inhabits, in eastern Fiordland at least, slow-seeping gullies—the steeper the better.
These boots have almost no traction left,” mutters Lloyd, setting off a small rockslide above a larger slip that stretches away beneath us. With an acicularis in his sights, he unpacks his scientific equipment his grandfather’s First World War entrenching tool and half a dozen well-used plastic bags—and sets about uprooting some young tussocks. A little levering with the entrencher plus a couple of good yanks and the whitish roots essential to a successful transplant emerge reluctantly from the dirt. Wind begins to howl; rain flings itself at us. With four small bags of plant material, we scurry back to the shelter of the car, clinging to tussocks for support.
Anyone who has tramped in precipitous tussock country will have relied, at times, on handfuls of well-anchored tussock to haul themselves upward. Despite a number of trampers slipping to their deaths on the slick leaf litter of tussocky bluffs, there are some extraordinary records of the steadfastness of these plants. William Grave, one of Fiordland’s pre-eminent explorers, used tussock as an anchor from which to abseil into Cleddau Valley from Homer Saddle on the first descent of the Grave-Talbot Pass, in January 1910.
“We had cut off all chance of climbing back. Downwards we must go. Each further stage was accomplished by tying the ends of a piece of snow grass [an alternative name for some tall tussocks] with a piece of string, and passing the rope through. There was not much danger of the snow grass giving way. The chief risk was that the string might slip off the grass. When our supply of string ran out we used our bootlaces”.
This technique is still used by desperate mountaineers on rare occasions.
Scientifically speaking, a tussock is not actually a single group of related plants but a growth habit—a particular arrangement of stems and leaves which forms a tuft of vegetation. The stems, or tillers, from which the leaves sprout are unusually tightly clustered. In North America, such plants are known as bunch grass. Bunching may have evolved to protect new growth from frost, as tussock leaves grow from the base, not the tip, and new growth is protected by surrounding tillers and the leaf litter that encircles each plant.
New Zealand has a particularly high percentage of tussock-forming grasses. It is not unique in this, but the habit is certainly a distinctive feature of our grasses, as is their relatively large size and evergreen nature. The dominance of the tussock habit may be related to the absence of mammals in New Zealand’s prehistory. Chionochloa species simply don’t cope with heavy grazing.
Those plants we generally call tussocks are a collection of grasses from three different genera that have adopted the tussock habit. The genus Chionochloa (chion = snow; chloa = grass) includes the snow tussocks, or tall tussocks—up to 2 metres high—that make up the grand, golden army that dominates our subalpine grasslands, furring the hills a tawny gold and forming a magnificent backdrop for numerous beer and car commercials. A few other species survive in isolated coastal and forest sites. Left comparatively undisturbed on account of their general fondness for altitude and inaccessible locations, Chionochloa are the lucky tussocks.
Less grand and altogether less fortunate are the short tussocks. Growing up to half a metre in height, they include such hardy species as blue tussock (Poacolensoi), silver tussock (P. cita) and hard, or fescue, tussock (Festuca novaezelandiae). With a penchant for lower country, short tussocks have had to compete over the last 200 years with the runholder’s arsenal of fire, exotic grasses and grazing stock, and also with the runholder’s enemies—weeds and rabbits. While some have fared better than others, none has been unaffected. Today it is almost impossible to find an area of unmodified short-tussock grassland in New Zealand.
Short tussocks and tall tussocks have distinct, if not altogether clear, origins. One of Lloyd’s research aims is to answer questions concerning their evolution. Chionochloa is a member of a relatively ancient southern-hemisphere group, and 22 of the 24 identified Chionochloa species are endemic to New Zealand, where the genus has probably existed since the Tertiary period. While the grass family is most likely to have originated in South America, our short tussocks appear to have arisen from ancestors that moved to, and diversified in, the northern hemisphere and then trickled back south.
Of the 450 Festuca species, only 10 are found within New Zealand. Because Festuca evolved on continents with large grazing mammals, it has developed traits that make it less palatable than some other grasses. Rub your hand down a leaf-blade of hard tussock and you’ll find it prickly and rough. This may be one adaptation that has enabled Festuca species to survive in New Zealand’s modified pastures, where many others have not.
Far from paddocks, snow-patch grass (C. oreophila) has evolved to live in shaded depressions in the mountains that retain snow even into the summer months. But eight million years ago New Zealand was a series of low-lying swampy islands with not a peak in sight. How, then, did the alpine tussocks evolve?
“We presume that tussock grasses survived in places where forest couldn’t—such as in Fiordland, where valley floors are often either too wet or too frosty,” Kelvin Lloyd tells me. “Also round the coasts, where there’s a lot of disturbance and trees get pushed back, grasses would have had a foothold. Similarly along rivers and on bluffs sticking out of the forest. We’ve still got species in all those habitats.
“Red tussock we met on the frost flats, and C. bromoides, in Northland, is strictly a plant of rocky coasts—it grows right down on the shoreline rocks. C. beddiei does a similar thing around Wellington, and then there are others that still live on bluffs within a forested landscape, like C. flavicans and C. conspicua.
“When the mountains came up, a whole lot of new habitats appeared, and that promoted speciation. We got our alpine species then.”
Periods of glaciation following this mountain-building phase also aided speciation by fragmenting widespread species into separate populations with no gene flow between them.
Fossil Pollen grains tell the history of New Zealand’s vegetation—a history palynologist Matt McGlone has spent much of his professional life unravelling.
Pollen grains—encapsulated within a tough almost rubbery outer coating—may persist for millions of years provided they come to rest in either a very dry or a very wet environment, where there is little biological activity. According to the pollen record, forest has dominated our landscape for the last 12,000 years, with grasses confined to river terraces, slips, peat bogs, the very driest parts of the Clutha and Mackenzie Basins, and areas above the tree-line. But it hasn’t always been that way.
There have been times when grasses have spread from their refuges to cover much of New Zealand. At the end of the last glaciation (14–15,000 years ago), for example, there was a cold pulse during which New Zealand was almost covered in grassland. But unlike the sweeping tall-tussock grasslands of today, it was a barren, eroding landscape of thin scattered grasses and scabweed plants.
“In fact, over the last 2.5 million years,” says McGlone, “for southern New Zealand the natural setting has been scrub grassland—only for brief periods did it have tall forest.”
Tall forest would have greeted the first human visitors to New Zealand around 900 years ago, but fire was soon to wreak big changes. Joseph Banks, gazing out from the deck of Endeavour, made the following observation in his diary on October 16, 1769:
“At night we were off Hawks Bay and saw two monstrous fires inland on the hills: we are now inclind to think that these and most if not all the great smoaks and fires that we have seen are made for the convenience of clearing land for tillage, but for whatever purposes they are intended they are a certain indication that where they are the countrey is inhabited.”
Natural fires caused by lightning were thought to have swept the drier areas of New Zealand every few hundred years, but when Maori arrived in Aotearoa, the frequency of fires increased dramatically.
“The big fires started about 800 years ago, at the end of the 12th century,” says McGlone. “That’s when we date the big moa bone pile-ups.”
Deliberate burning continued after moa had become extinct, which raises doubts about whether Maori cleared forest to chase out moa. McGlone believes they had other reasons.
“Forest didn’t really have a lot of food in it. There were some birds but not a lot else, and it also impeded navigation and travel. With a lot of lawyer vines and tangled small-leaved shrubs, it would have been a nightmare to get through.”
Clearing forest would have made for quicker travel overland, and replacement vegetation would have been richer in bracken fern, with its palatable rhizomes, and in bird life.
The burning of the forest was good news for the grasslands. Both short and tall tussocks rapidly colonised previously forested areas. Snow tussocks, especially those tolerant of drier conditions, such as the narrow-leaved snow tussock (C. rigida), became widespread at lower altitudes. Short tussocks migrated up-slope from dry valley bottoms to meet them. In wetter areas, such as Southland, red tussock raced across the low-lying hills. Forest surrounding the volcanic plateau and Lake Taupo was replaced by 660,000 ha of red tussock. Maori fires enabled indigenous grasslands to spread from 1.5 million hectares to around 8 million hectares, or 30 per cent of the land area, mostly in the drier eastern parts of both islands and in the central South Island.
With the arrival of European settlers and their appetite for timber and pasture, the rate of deforestation accelerated dramatically. In the single decade from 1890 to 1900, 27 per cent of New Zealand’s existing forest was cleared—13 per cent of the total land area. While most of this went into pasture, tussock made a little extra ground.
“All the tussock grasslands that you see now below the tree-line are fire affected,” says McGlone, “and 95 per cent are the product of fire alone.”
The alpine grasslands, although spared such radical “development,” were not altogether untouched. Introduced mammals such as sheep, deer and hares began to graze their way up, feeding on the more palatable plants, pulling out and trampling tussocks and herbs, and leaving behind a higher concentration of less edible species like Dracophyllum and wild Spaniard.
New Zealand’s luxurious growth of native grasses looked highly promising for stock, and in 1876 the government issued an order “that a work on the native grasses of the Colony should be prepared . . . to be accompanied by an essay on the grasses and forage-plants likely to prove useful in New Zealand.” The result was The Indigenous Grasses of New Zealand, published in 1880 by John Buchanan, a draughtsman and botanist to the Otago Geological Society.
The tufts of tussock were regarded as “unsightly and disfiguring to the cultivated landscape.” Buchanan recommended introducing P. foliosa from the Auckland Islands to the mainland but lamented that it might be “difficult to overcome the prejudice which exists here in New Zealand against all large tussac grasses, arising no doubt from an ignorance of their true value.” Their “true value” to the settler was in providing shelter for stock in bad weather and at least a basic forage plant when the smaller inter-tussock species were blanketed by snow.
In the 1860s and early 1870s, farmers relied almost entirely on native grasses for grazing. There were few fences, so cattle and sheep roamed high into the subalpine zone. Land was burned frequently new growth was more palatable than old—and grazed heavily. Neither government officials, who demanded minimum stock numbers in order to secure leases, nor farmers had any idea how slow New Zealand’s tussock grasslands would be to regenerate. Stock numbers rose sharply. Between 1870 and 1880 the number of sheep in New Zealand leaped from one million to 10 million. Rabbits, which had been introduced in the 1830s, suddenly came on in vast numbers.
As a result of the ensuing destruction of tussock, water drained more rapidly from the open country and some areas became as dry as deserts. In Otago, between 1877 and 1881, 77 sheep runs covering over 600,000 ha had to be abandoned.
Concern about declining productivity and degradation of tussock grasslands was voiced early. “It may be questioned,” wrote Buchanan in 1880, “whether the entire destruction of the native grasses, especially the larger tussac kind, is judicious.” Again he noted that apart from their food value, these plants provided useful shelter for stock.
However, tall tussocks also inhibited stock movement and were not favoured by sheep. After repeated burning they eventually gave way to short tussocks, which were then over-sown with more palatable exotic grasses. Only at high altitude were tussocks spared. In the short-tussock grasslands, stock grazed on the most succulent plants—herbs and shrubs—before turning to the more palatable tussock species. The least edible plants—hard tussocks such as F. novaezelandiae and F. matthewsii survived for a time under burning and grazing, but the open pastures, with scattered plants of low stature, were vulnerable to invasion by rabbits, hawkweed (Hieracium spp.) and, in the driest areas, native scabweed. Although stock numbers dropped and pastoral production declined, the grasslands continued to degrade.
The 1948 Land Act, which introduced 33-year pastoral leases, encouraged farmers to invest in their land. The subsequent advent of aerial topdressing—which allowed fertilising and the spreading of rabbit baits over sizable areas slowed degradation dramatically, as did improvements in fencing technology, the introduction of the poison 1080 and increased research into pastoral management.
But while the decline of our tussock grasslands has slowed, it has not halted. Of the 3.9 million hectares now classified as pastoral tussock land, half a million hectares are dominated by hawkweed or bare soil and a further one million hectares have a “significant and increasing” presence of hawkweed. The Ministry for the Environment report The State of New Zealand’s Environment 1997 reached the following bleak conclusion: “It now seems that, in spite of the apparent recovery, the long term trend for the tussock grasslands is one of inexorable decline in both species diversity and production.”
“The short tussock grasslands,” says Matt McGlone, “are just falling to pieces in front of our eyes.”
Many New Zealanders cherish the high country. It is as much a part of national folklore as of natural heritage—a symbol of the frontier and the rugged independence we like to imagine lies at the heart of being a New Zealander. It is not just runholders who feel a powerful connection with this landscape. Trampers, mountain-bikers, hunters, environmentalists, horse trekkers and back-country skiers all relish its sweeping expanses. Artists, writers and poets draw inspiration from it, while marketing managers use it to sell beer and vehicles to city slickers. Little wonder the issue of current and future management arouses a wide range of opinion.
The practice of burning tussock is highly contentious. Every spring columns of smoke choke the still blue air and streaks of amber puncture the night. Although the rotation period these days is probably 20 to 30 years, some tussock is burned most years.
No subject is as likely to split a Central Otago town, with rumours of fires that got out of control and complaints about the negative impacts on tourism. But farmers are adamant that the strategic use of fire is an essential, although now minor, part of farming practice. It keeps back encroaching woody vegetation, improves stock access and brings a flush of palatable new growth. Passions on both sides run exceedingly high.
Stepping squarely into the inferno is Landcare Research scientist Ian Payton, keen to inform the debate with some data on the effects of burning. He patiently explains that “government funding for research in the high country has collapsed in the last 9–10 years, largely because groups couldn’t agree on what research was needed.”
Previous studies tended to consider the impact of fire on individual plants, rather than on whole landscapes and ecosystems affected by management decisions. Now, government science and management agencies, fire-control authorities, local bodies and farmers are cooperating in a multi-year study on the effects of burning on snow tussocks in central and coastal Otago.
Payton hopes to determine whether fire, with or without grazing, causes long-term damage to tall-tussock grasslands by depleting their fertility and degrading the native plant communities, and how spring fires, when the soil is still damp, differ from summer fires. Summer fires kill more tussocks and destroy a far higher percentage of the plant biomass than spring fires. While landowners wouldn’t dream of burning under dry summer conditions, the possibility of accidental fire remains.
“When you burn a tussock,” Payton explains, “it completely changes its way of operating. It drags nutrient reserves up from the roots and pushes them into new foliage.”
Common practice is to burn in spring and then spell until about February or March, by which time the plants are flushed with new shoots. “But graze that new foliage off,” says Payton, “and the plants are really in trouble.
“Tussock isn’t generally good fodder, but in the two years after it has been burned, sheep will run at fences for the freshly burned tussocks because those shoots are higher in nutrients such as phosphorous, potassium and nitrogen. I don’t think the spring fire is the problem because anything that was vulnerable to fire went eons ago. What remains has survived fire for 100–150 years or longer.”
Preliminary results from some of Payton’s burnings are coming in. A spring fire at an inland site, on Mt Benger, near Roxburgh, consumed a modest 30 per cent of the biomass, leaving a layer close to the ground relatively unharmed. However, a month earlier at Deep Stream, nearer the coast, 60–70 per cent of the biomass went up in smoke, and the ground layer was badly burned. Lower soil moisture was the explanation. Summer burns at Deep Stream have resulted in the death of the majority of snow tussocks. Plants attempted new growth but winter frosts destroyed this before it had hardened off.
Adding to the tensions in the high country is the process of tenure review, which will redistribute ownership of 2.7 million hectares—10 per cent of New Zealand and 20 per cent of the South Island—currently under pastoral lease from the Crown to some 340 high-country stations. Runholders have the option of owning their most productive land freehold in exchange for ceasing to graze areas of “significant inherent value,” which will pass to the Department of Conservation for protection and recreational purposes. It sounds like a clean, surgical procedure. It is not.
On a clear autumn day at Lake Hawea, retired Professor Alan Mark addresses the Upper Clutha branch of the Royal Forest and Bird Protection Society. In the audience are a number of local runholders. Described by some as the “Professor of Political Botany” and the doyen of tussock grassland ecology, Mark is credited with raising the public profile of non-forest ecosystems, in particular grasslands. He is also credited with speaking his mind, not always with the greatest regard for diplomacy. A poster on his office wall reads, “If you want to be an ecologist, you have to stir things up a little.”
“These issues,” Mark emphasises, “are too important to leave to politicians to decide.” Mark may be well past the age of retirement, but his dogged determination seems undiminished. To his audience of mainly elderly conservationists, he describes the gradual process of acquiring tussock grasslands for conservation through tenure review. The list of battles seems endless. Map after map goes onto the overhead projector delineating successes (areas reserved) and losses (areas remaining in pastoral use).
“[Tenure review] is a oncer,” he warns. “We go through this in our generation and then that’s it—we’ve got to get it right.”
Yet Mark’s “successes” and “losses” are seen in a different light by the farmers present who are faced with giving up vast tracts of land and parts of their high-country heritage.
Later that afternoon, the Forest & Bird group drives out for a walk around Dingle Burn Station, on the eastern side of Lake Hawea. The owners, the Mead family, are supported by other farmers, such as the Emmersons, from the Lindis Pass, and Arthur Borrell, long-time owner of Branches Station, near Queenstown.
The Meads are generous with their hospitality, despite obvious reservations. This is a rare meeting of two groups with very different ideas about the future of the tussock lands. Both sides show grace and willingness to communicate, but tempers lie close to the surface and erupt from time to time. Mark is accused of being one-eyed and trying to brainwash the public. He is followed to make sure he doesn’t take photographs that could be used “against us.” One farmer mutters, “It’s a war.”
We gaze towards the highest tawny peaks—the areas that are likely to go to DoC through tenure review. Bridget Mead declares that her daughter has the right to muster along those tops, as she has done—it’s a part of her heritage. Mark argues that other New Zealanders also feel passionate about the land, and that it looks too bare to be considered productive. This is the crux. How should this land be managed?
Conservationists claim that the historic degradation of the high country is not evidence of good stewardship and that many areas are so depleted they must be taken out of production. Farmers say they’ve learned much from the last 150 years and that the past 50 years have seen significant restoration.
“Farmers have changed,” explains John Aspinall of Mt Aspiring Station, “to a much more integrated approach to farming with the emphasis on production per head and looking after the environment, rather than being concerned mainly with stock numbers.”
He argues that continued grazing is necessary to prevent the spread of weeds. “In the tussock grasslands, if we walk away from management, pines, Douglas fir and Hieracium [an invasive ground cover that forms a smothering mat] will take over. We’ve brought so many exotic species with us, both animals and plants, that you can never go back to pre-European times.”
Integrated management (using covenants, for example, to safeguard areas of threatened vegetation) under continued pastoral stewardship offers, he believes, the most sustainable future for the grasslands.
Farmers are also concerned that an increase in rank grasses and tussocks, along with more recreational visitors, will create an unacceptable fire hazard right in their back yard. Payton is not convinced by the fire-hazard argument. He believes tussock land is combustible almost year-round and that adding to the amount of fuel doesn’t increase the risk significantly.
Aspinall, a respected leader in the farming community, assures me that despite the tensions, there is a great deal of common ground between the conservationists and the runholders. Everyone wants the same thing—sustainable management of the high country and opportunities to enjoy it recreationally—but they differ over details and approaches.
DoC is set to gain approximately one million hectares of mostly modified grassland through tenure review. What is it going to do with it? It will have to consider such thorny questions as what is natural, the vegetation of 150 or 1000 years ago? Will it have to burn the Lindis Pass periodically to prevent it reverting to scrubland and eventually to forest? Will our grasslands, expanded over the last thousand years by fire, shrink to their previous limited range? Should we allow them to?
Tussocks at low and mid-altitude are essentially invasive, colonising areas of disturbance but, where a sufficient seed source remains, eventually being overtaken by scrub and forest. A small reserve in the Rock and Pillars Range with an old, intermittent shrub zone is rapidly reverting to scrub. Yet tussock cover in a drier reserve at Black Rock, monitored since 1971, has increased in spread and height, while the shrubs have hardly changed.
“You can’t generalise or predict what tussock cover will do,” says Mark.
Under national-park policy, burning-off is a land-management option, but its use is bound to be controversial. Conservationists strongly opposed Payton’s modest burning experiments on land owned by DoC, although DoC itself was happy. Payton’s experiments have taken place on private land.
Meanwhile, Mark and the conservation lobby have enjoyed some success. In 2001, Korowai/ Torlesse Tussocklands Park in inland Canterbury was created, the first conservation park in the eastern high country and a landmark for the conservation of non-forest ecosystems. With tenure review, more reserves are set to follow. Indeed, as recently as May 2003, a second tussock conservation park of 20,000 ha opened in Central Otago’s Lammermoor Range.
And what of the lower country—the former domain of the short tussocks—as it comes under more intense farming pressure? Little is being recommended for conservation through tenure review, because it is generally more productive and the indigenous vegetation has already been seriously degraded. Grapevines, deer farming and lifestyle blocks, too, are all eating up large tracts of formerly semi-natural grasslands. But entomologists are crying out that native invertebrates will be threatened when the lower lands become freehold and grazed more heavily.
Invertebrates tend to draw the short straw in conservation management. The Cromwell Chafer Beetle Reserve—touted as the world’s first conservation area dedicated solely to an insect—is an anomaly. Yet invertebrates make up the bulk of species in New Zealand’s native fauna.
In Payton’s study, typically 4–5000 individual invertebrates belonging to 7–800 species have been found in each square metre of tall-tussock grassland. A huge surge in the discovery and description of new species has begun, thanks to tenure review, as entomologists search many lowland and high-country tussock communities for the first time.
The grasslands turn out to be teeming with insects. Entomologist Brian Patrick of Otago Museum has described the mountain ranges of Central Otago as providing “habitats for the most diverse and spectacular insect fauna in any New Zealand region.”
And not just insects. Flat worms, spiders, centipedes, millipedes and snails together with weta, cockroaches, weevils, earwigs, beetles, mealy bugs, aphids and ants all make their home in the tussock grasslands. Flitting, buzzing and jumping above them are butterflies, moths, cicadas, grasshoppers, flies and wasps. Together, these hordes provide a smorgasbord for lizards and birds.
Some creatures are real oddities. For instance, Patrick recently discovered a new species of stonefly. “These stoneflies don’t fly—they don’t even have wings—and they don’t live around stones,” he comments. Normally stoneflies are found in streams, but this species has adapted to life in the damp centre of the copper tussock
(C. rubra cuprea) on Dunedin’s Swampy Summit. Its whole life history takes place within the plant, adults and larvae both feeding on detritus in the heart of the tussock.
“Since we’ve burnt snow tussock and dried it out,” says Patrick, “I’m sure we’ve eliminated many populations of this sort of thing.” Blue tussock (P. colensoi) is a favoured food plant for many insects but has been much reduced in abundance by grazing animals, which also seek it out.
The country’s moth fauna, which still numbers about 2000 species, has probably suffered considerably through damage to tussock land. Many moths and butterflies make use of the shelter afforded by the tussock habit to lay their eggs. Their larvae often eat the leaves and pupate in the heart of the plant. For instance, the larvae of tussock butterflies (Argyrophenga spp.) feed on silver and tall tussocks, whereas Butler’s ringlet (Erebiola butleri) sticks to low alpine Chionochloa species in the wetter western South Island mountains.
Larvae of the Otago ghost moth (Aoraia rufivena) spend their days underground but emerge at night to feed on leaf litter, including that of snow tussock. The females of many grassland moths have become flightless, in some cases their wings reduced to stumps on either side of a large egg-filled abdomen.
Many spiders take advantage of this abundance of insects. Trapdoor spiders build their burrows in open country, covering the entrance with a finely woven lid and sitting just inside, awaiting their prey. The common wolf spider (Lycosa hilaris) shelters in the base of tussock plants. Another wolf spider (Anoteropsis flavescens) lives only in swampy tussock grasslands from Dunedin south. New Zealand’s only species of lynx spider (Oxyopes gracilipes) is also a grassland inhabitant. A large, distinctively coloured spider was identified in the tussock of Cardrona Valley in 1969 but has never been found since.
Patrick argues that the wealth of tussock invertebrates indicates the pre-human grasslands were more extensive than is suggested by pollen analyses. Many grassland insects have flightless females and are very site specific.
“It’s hard to imagine them moving far. Places like the Mackenzie Country, where people say the grasslands only appeared after the forests—I don’t believe it. There are too many flightless things—not just moths but chafer beetles, all sorts of things that wouldn’t live in a forest ecosystem and found only in the Mackenzie Basin for instance. They didn’t just arrive after the Polynesian fires.”
All may not yet be lost, however. Native animals don’t fastidiously stick to native vegetation. Many invertebrates, such as grass moths (Crambidae spp.), have adapted well to modified pasture, and the larvae of others have taken to feeding on exotic herbs. This means modified grassland areas are still worthy of conservation.
Of you wander along the tussocked tops of inland Otago, a scurrying movement may catch your eye as a shiny tail twists into the leaf litter. Peer deep into the crevices of the schist tors that characterise the region and you might find a pair of eyes looking back at you. If they blink, they belong to a skink; if not, you’re looking at a gecko, and it will almost certainly outstare you. Both creatures feed on invertebrates and the fruiting shrubs, such as pink snowberry (Gaultheria macrostigma), that grow between the tussocks.
On sunny days, skinks bask on the rocks, while geckos, which are mostly nocturnal, press their backs up against the warm roofs of their crevice homes.
According to herpetologist Mandy Tocher, even our common skinks may not be common for much longer. Modification of the grasslands has greatly reduced skink habitat and opened it up to a fearsome array of predators. Lizards may be able to survive a light grass fire by retreating into a deep crack in the rock, but they cannot survive relentless hunting by feral cats, ferrets, stoats and weasels.
At Macraes Flat, an hour’s drive north-west of Dunedin, Tocher and other DoC staff are struggling to maintain the last sizable populations of grand and Otago skinks. But the odds are against them. Outside the “Lizard Lounge,” an old farm hut with a soot-blackened ceiling where the team eats and sleeps, is a freezer containing the bodies of well-fed cats and ferrets caught by resident trapper Neville Mitchell. In the autumn of 2002 Mitchell caught six cats a day, and New Zealand also boasts the largest population of wild ferrets of any country in the world. The grasslands are overrun and the lizards are under siege.
So, too, are birds. Harriers and falcons survive on ample prey, but ground birds such as weka, once common throughout the tussock grasslands, have all but disappeared. The native quail, or koreke (Coturnix novaezelandiae), became extinct some time after 1860 because of hunting by Maori and Europeans and reduction of tussock habitat by burning and grazing.
The takahe is a true grassland bird, plucking tussock tillers and seeds for food and laying eggs in a raised bowl of grasses under the shelter of tussock leaves. The bird’s method of plucking tillers stimulates new growth. Where a tiller breaks, a fresh shoot forms to replace it. Unfortunately, red deer favour the same tussock species as takahe, and their method of feeding—simply severing the leaves with their teeth—does not stimulate regrowth. Deer populations have had to be controlled in part of Fiordland to arrest the decline of takahe.
As a modest offset to the woes that have come the way of tussock since mammals invaded the high country, there is now considerable interest in using the plants for revegetation work in areas where tussock occurs naturally. For instance, all skifield operators in the south revegetate disturbed areas with tussock. In at least one instance ground that has been mined for gold has been replanted in tussock, and the plants have been used extensively around the aluminium smelter at Tiwai Point. While a few vigorous species, such as blue tussock and silver tussock, may become established from direct-drilled seed, most, especially the tall tussocks, need careful nursery rearing for a couple of years, by which time they are 20 centimetres or more in height and can be planted out. Seedlings raised at low altitude may have to be frost-hardened before being planted at higher elevations.
Collecting tussock seed also has its difficulties. Flowering in tall tussocks is particularly irregular. In those few years they do produce seed, much of it may be damaged or destroyed by insects. Mature tussocks can be divided into smaller plants, with a minimum of around 10 tillers, but these, too, need nursery care for a year before being planted out.
Ironically, while tussocks have been under siege in their natural refuges, they have come into vogue over the last decade as landscaping plants in a host of very unnatural environments. When John Baker of Home Creek Nursery, Manapouri, took over a DoC revegetation nursery about eight years ago and decided to concentrate on tussocks, “everyone thought I was mad,” he says. Today he sells 150,000 to 200,000 tussock plants a year, belonging to 20 or 30 species.
“They are good for holding banks, stopping erosion, and make a striking and maintenance-free garden,” he says. While the tall tussocks do not generally thrive in the north of the country, many of the smaller Poa and Festuca species flourish just about anywhere.
Although no dainty urban planting can begin to capture the magnificence of the tussocks of the Desert Road or Central Otago, the recent enthusiasm for tussock grasses in gardens and around city high-rises is introducing these distinctive plants to a new range of people. Their swirling textures and soft curves create a mesmerising contrast with the rigid stems of most shrubs, and the range of textures and colours available across different species is vast. These urban plantings might just provoke a curiosity about our real high-country grasslands and their future, and no harm can come from that.