THE TORLESSE RANGE

Forest and Bird, Volume 21, Issue 4, 1 November 1990, Unnumbered Page

THE TORLESSE RANGE

A Tussockland Conservation Park

by Forest and Bird South Island field officer Mike Harding With the hot summer sun baking behind, you run with giant strides down a 30 degree slope, each step sinking deep into shattered rock fragments, the dust swirling around your boots. Below, the broad plains are stretched out like a carpet and sedentary sheep watch silently from the rock outcrops to the side. And, as you come to a sliding stop and the dust settles, , flashes of colour show amongst the angular stones, bright flowers of the unusual plants that share this slope with lizards, butterflies and wetas. The top of the steep slope is framed hundreds of metres above by teetering rock ridges. From a dark speck spiralling against the sky, the sharp cry of the kea is heard. Far below a small stream winds its way between terraces of golden tussock and the jumbled boulders at the base of the slope. This is Canterbury. Not the peopled patchwork of the plains, or the wild snowy mountains of the main divide, but the dry foothills range that separates the two — a mountain wilderness at Canterbury’s doorstep.

HE TORLESSE RANGE lies one hour west of Christchurch by car. It is a barrier of ancient seafloor sediments uplifted to higher than 2000 metres by the same forces that raised the mountains of the main divide and the Kaikoura Ranges. The range lay in the path of the first transalpine travellers, who knew it by the name of Otarama, and who sought sustenance and solace from its valleys and peaks. It commanded the respect of Charles Torlesse, the first European to climb its slopes, who gazed at the "romantic and chaotic mass of mountains to the westward" from the mountain that now bears his name, and who named Starvation Gully when hunger forced him to choose between eating his donkey or his dog. (Both were spared by the arrival of an unfortunate weka!). Now the main transalpine highway winds over Porters Pass and through Starvation Gully at the southern end of the range and the Midland railway line follows the precipitous gorge of the Waimakariri River to the north. Ancient Screes To travellers on these routes the Torlesse Range may appear barren and desolate, a pile of broken rock devoid of vegetation. The finely-bedded sedimentary rocks of the range are greywackes and argillites which have been folded and twisted during uplift. When weathered by the extremes of a mountain climate, they shatter to fine fragments and form the screes that run from mountain top to valley floor. If exposed to heavy rainstorms these screes would move rapidly to feed the rivers running onto the plains. The screes are surprisingly stable. They move only gradually, and then usually only at the surface, except in rare and catastrophic storm events. Sediment yields of the rivers draining the Torlesse Range are only a fraction of the yields of West Coast rivers which drain completely forested catchments. This is because rates of uplift and annual rainfall are significantly reduced east of the main alpine fault and in the lee of the predominant westerly winds. Dating of screes by measuring weathering rinds on rock surfaces indicate that often these rocks have hardly moved for hundreds of years. "I was amazed at how stable the scree slope was,"" commented one keen participant at Forest and Bird’s 1990 high country Easter gathering, "I didn’t expect to be able to stay standing!" A scree only forms where the angle of the slope lies between 30 and 35 degrees; where a source of shattered rock fragments is present; and where the annual rainfall is low. Greywacke screes are found only on the east of the South Island in Canterbury and Marlborough, contributing to the bare appearance of the foothills ranges. The more specialised plants and animals that have colonised these screes are restricted to areas where the annual rainfall does not exceed 2500 mm. Curious penwiper plants (Notothlaspi rosulatum) form rosettes above the rock fragments, black scree cotula (Leptinella atrata) and Haast’s scree buttercup (Ranunculus haastii) appear in spring, flowering quickly in the short, harsh alpine summer. Disguised by its dull colouring and inconspicuous flowers, the fleshy lobelia (Lobelia roughii) nestles among the stones and the bright greens or reds of the leafy scree willowherbs

(Epilobium pycnostachyum) provide contrast to the dull grey or black of the rocky slope. All are scree obligates, growing only on these greywacke screes, where summer temperatures can soar to 50 degrees in the midday sun and plummet to below zero at night. These plants are able to survive, and even flourish, in such extreme conditions. They have evolved to tolerate the desiccating climate, the short harsh growing season, and movement of the scree surface. Beneath the scree surface lies a thin hard crust which, with the overlying stones, protects the soil below from water loss and helps stabilise the surface layer. Even in the hottest weather the soil remains moist, so scree plants have evolved complex and extensive root systems to exploit this water. Succulent leaves, fine hairs and cushion growth forms are other adaptions to an extreme climate. Most scree plants are summer-green herbs. They die away to a taproot or rhizome in winter and re-emerge in spring after snow melt. When the scree moves they survive by either having tough stems, buds protected by whorls of leaves, or small leaves connected delicately to the stem and root system which break easily and are quickly replaced when conditions stabilise. They are also inconspicuous, no doubt to help escape the hungry eyes of the ubiquitous alpine grasshoppers. Sharing the screes with the grasshoppers and specialized plants are wetas, cockroaches, lizards, and butterflies. Sheltered beneath the stones a weta (Deinacrida connectens) scavenges for plant and animal fragments, the female reaching more than 6 cm long, mouse-sized and dwarfing the male. Lower down is the scree cockroach (Celatoblatta montana) which is confined to

these dry eastern ranges and the common weta (Hemideina maori). Another undescribed cockroach (Celatoblatta sp.) lives in areas of very dry rock and scree within the forest. Skinks scuttle amongst the scree stones or crevices of the rock bluffs sheltering from the baking daytime sun and emerge to soak warmth from the rocks in the cool of the evening. The smaller inhabitants are less well known but have not escaped serious study.

Former Reserves Board member Peter Johns has peered closely at many specimens to describe the differences that separate the cockroach species and he talks enthusiastically of a zone centred on Lake Coleridge and the southern Torlesse which is the geographic centre for the invertebrate fauna of the drier eastern foothills. Conspicuous Animals It is the more conspicuous animals such as the inquisitive alpine parrot, the kea, that visitors are likely to notice. Peter Newton in his classic high country book Wayleggo describes locating kea nests from the unusual whistles of nesting birds. Musterers have recorded kea nests in the Kowai Valley at the southern end of the Torlesse Range. Despite years of pressure from hunters, the now fully protected kea is still present. Phil Beckett, who worked voluntarily for Forest and Bird on the Torlesse proposal, tells of the time he was surrounded by a group of 14 kea in Torlesse Stream. Many of our more common birds inhabit the forests, shrublands and grasslands; pipits roam the open ridges and falcons patrol the valleys. It is not only the scree plants and insects which make the Torlesse Range a special place. The high frost shattered ridges are home to the hard cushion plants such as the vegetable sheep (Raoulia eximia and R.mamamillaris) and Phyllachne colensoi. South Island edelweiss (Leucogenes grandiceps) and furry Haastia species have established a foothold in the shelter of rock crevices and a range of alpine daisies (Celmisia spp.) occupy the more stable sites. Where snow cover insulates the ground from winter temperature extremes an alpine grassland of

slim snow tussock (Chionochloa macra), and on wetter sites, mid-ribbed snow tussock (C. pallens) and snow patch grass (C. oreophila) are present. Many of our alpine plants were first collected from the Torlesse area and Foggy Peak is still a popular destination for botanical field trips. Below the high alpine tops the original vegetation of the Torlesse Range has been altered by burning and grazing. Fires swept the area hundreds of years ago and fire was

used by the first runholders to open the country for sheep grazing. Stock once roamed high over the open tops of the range and were mustered down to the lower country before the winter snows. Nowadays the upper country has been destocked, either voluntarily, or as part of soil and water conservation plans. Where stock pressure has been reduced and burning has ceased the rich Dracophyllum acerosum shrubland has regenerated and forest may eventually return.

On drier sites manuka or kanuka dominates and on the wetter terraces and higher slopes a tall tussock grassland remains. Above this, and in the scree-filled gullies, the open rock will remain in its natural sparsely vegetated state. Remnants of the original mountain beech forest still cover the steeper and less accessible northern and eastern parts of the range, and are now vested with the Department of Conservation as stewardship areas. Apart from the forested areas the entire

range, including its alpine tops, is held in pastoral lease or pastoral occupation licence tenure. The range and its major summits of Castle Hill Peak, Mt Torlesse and Otarama separate the Castle Hill run to the north-west from Brooksdale in the south-west. The smaller Avoca run occupies the north-eastern part of the range and the freehold Mt Torlesse station covers the foothills to the south-east. The pastoral run tenure allows the grazing of sheep and cattle while retaining the land in

Crown ownership. Over recent years run development has led to the intensification of grazing on the lower country and the destocking of the higher and steeper land. Land over 900 metres on Brooksdale Run is held under pastoral occupation licence with no right of grazing. The licence expired in June 1990; the land is now likely to pass to DoC. Alpine Playground While musterers may no longer trudge the steep ridges and screes, it is common to see people's smiling tanned faces emerging along the Porters Pass road after a long and satisfying day botanizing or walking on the range. And just two hours from the road, in a different season, you will hear the hiss of a primus stove from the candelit Kowai Hut as weekend adventurers prepare crampons and ice axes, for the ascent of the snow covered Mt Torlesse or for the steep climb to the Gap. This gunsight notch in the ridge provides stunning views of the Southern Alps to the west and Banks Peninsula to the east. The Torlesse Range has long been a destination for Canterbury recreationists. Walkers and trampers explore the valleys and peaks, back country skiers and climbers pace the winter snows, botanists revel in the rich and unusual plant communities, and travellers gaze at it from most parts of the highway from Christchurch to Arthur's Pass — an alpine playground within sight of Christ-

church. Yet legal access points remain unmarked and facilities are few. Wilding conifers emerge from the Dracophyllum shrublands, introduced broom invades the riverbeds, deer and chamois browse the palatable alpine herbs, and unscrupulous gardeners plunder alpine plants from the roadside at Porters Pass. And nowhere is a dry eastern range protected within our parks and reserves network. This historic bias in our protected areas system towards the high and forested mountains is nowhere more dramatic than in Canterbury. While extensive areas of beech forest and alpine tops are protected in Arthur's Pass and Mt Cook National Parks and in Craigieburn and Lake Sumner Conservation Parks, only a scattering of pocket handkerchief reserves offer protection for tussock grasslands of the high country and no parks or reserves are centred on the dry rock and scree ranges. Historical circumstance meant that the foothills ranges of Canterbury, right to the ridge tops, were included in pastoral runs. Forested areas were eventually excluded as State Forest (now Stewardship Area), and for a time establishment of forest on the open rock and scree was considered essential to prevent whole mountainsides slipping to the sea. Now, a recognition that the barren appearance of these mountains is a largely natural phenomenon, and the gradual retire-

ment of much of the higher country from grazing, casts the eastern foothills of Canterbury in a different light. Few tussock grassland reserves exist anywhere in the east of the Main Divide. Scree and dry rock plant communities have been largely ignored. Yet they are two of the more unusual elements of our native flora, and both remain largely unprotected. The Torlesse Range is an area that has been a focus for Canterbury's scientific exploration and recreation for many years. It has remarkable and distinct native plant communities. The range’s economic importance for grazing is low and local support for its protection is high. It provides a wonderful opportunity to correct the imbalance inherent in the reserve system and to give formal recognition to an area that is refreshingly different from our traditional parks. A Torlesse Conservation Park would allow us to actively manage an area of scree, rock and tussock grassland for conservation and recreation and to control any threats to their integrity. It would encourage us to advocate a broader concept of conservation, one which includes all ecosystems, and enable us to enhance the opportunities for people to discover these special screes and grasslands. Ps