Over several thousand years successive modifications have transformed the mountainsides of Central Otago from a forest dominated environment to one dominated by tussock grassland. Evidence suggests that the northern slopes of the Pisa Range were clothed in forest of silver beech, Halls totara until destroyed by fire about 800 years ago. Earlier about 2500 years ago, evidence indicates shrubland, tussock, and matai, celery pine, silver beech and Halls totara were present. The forests were replaced by fescue tussockland, with silver tussock and grasses.
Pastoralism and goldmining in the 1860’s transformed the vegetation as much of the woody vegetation was used as firewood or mining timber. This depleted the lower slopes and produced an environment ideal for rabbits and large areas became established in sparse scabweed cushionfield. The introduction of aerial over sowing and topdressing, control of rabbits and careful stocking reduced the area of severely depleted lands and resulted in largely exotic pasture up to altitudes of 1000 metres.
Native shrub - Corokia cotoneaster
Native shrublands of low to mid altitudes have been commonly reduced, are now restricted to small areas of fire refuges and include Matagouri, Coprosma propinqua, Olearia species and kanuka. Kanuka and matagouri have strong regenerative abilities – matagouri favouring topdressed slopes; and kanuka favours many extensive areas.
Mahaka Katia Scientific Reserve (D.O.C.)
Mahaka Katia Scientific Reserve (D.O.C.)
In 2001 a small 26ha pocket of land, where one of the highest concentrations of rare plants in New Zealand grows, was purchased by the Nature Heritage Fund as a reserve. Known as the Mahaka Katis Scientific Reserve and located at Pisa Flats, the reserve is located opposite Mt Pisa Station on State highway 6 about 8km from Cromwell.
The semi-arid land comprises drought resistant native herbs and grasses, including Poa cita, silver tussock. Plants only found in the area include Myosotis uniflora and M. craspedia as well as Leptinella and Carmichaelia (broom). The land has been described as the best saline site remaining in the Upper Clutha region and was being threatened by expanding vineyard developments. Other uncommon, rare or little-known plant species found in the area include the sedge Carex decurtata, a cress Lepidium sisymbrioides, and tiny fern Ophioglossum coriaceum.
Water is the life blood of the Cromwell area and without it the land would revert to the barren sands and gravel that characterised it in the 1860's. The extremes of temperature ranging from 30°C in the summer to -r°C in winter, coupled with an average rainfall of 400mm has resulted in the survival of the fittest amongst the uncultivated plants of the area.
On the farms, irrigation and over sowing with European grasses has removed much of the native ground cover. However, along the roadsides there is a profusion of colour as the hardier types of plant life begin their flowering season. Prominent amongst these with pale orange petals and greyish leaves is 'Johnnygo-to-bed', so named from the speed with which its petals fold when shaded from the sun. Eschscho/tzia californica, Californian poppy, call it what you will, it makes a glorious sight when in full bloom.
Here and there amongst the sparse ground cover is the pale blue of Vipers bugloss, known locally as blue borage. Verbascum, with its thick, felty leaves and holly-hock like stem of yellow flowers quickly asserts itself on any bare land. Sometimes known as tobacco plant, verbascum's dried leaves would have provided an acrid smoke for any early settler desperate enough to try it.
The spur valerian Centranthus ruber with its panicles of star shaped flowers and erect stems adds an occasional splash of scarlet to the hillsides, and especially along State highway 8 at the entrance to the Cromwell Gorge. In Central Otago it seems to be a refugee from an early settler's flower garden but in Italy its leaves are used in salads. The daisy (Compositae) is the largest of the New Zealand plant families. Along the roadsides its ubiquitous white petalled head appears in casual clumps adding its particular charm to the wasteland.
The New Zealand daphne (Pime/ea) can be found off the roadside on the lower slopes of the Pisa Range. Erect and branching, its tiny flowers have a beautiful perfume. Less beautiful are the flat cushions of scabweed that cling to remnants of soil on barren land and stony riverbeds. Unlovely as it is, scabweed does have a use as it forms a nursery for other plants in the regeneration of new grasslands.
Likely to be close at hand is the curiously leafless native Cromwell broom, Carmichae/ia compacta. The gullies are home to the prickly wild Irishman or matagouri. From November until January this jumble of prickles produces a tiny white flower with a sweet perfume.
The slopes of the Pisa Range provide a profusion of sub-alpine plant life but before you are tempted to go exploring, check at the nearest farmhouse. You will seldom be refused entry.
For those who prefer the quiet charm of the home flower garden a stroll around the older part of the Cromwell township can be rewarding. This is an excellent environment for roses and there are few gardens without at least one bush. If it is the blooming season look for the display in the formal garden behind the Swim Centre. There is a handy car park off Barry Avenue or Waenga Drive, or you can take a stroll from the Mall past the memorial fountain off Waenga Drive. Included in the gardens is one of the largest sundials in Australasia.
The Australian harrier is the most common native vertebrate species, with the endemic New Zealand falcon being widespread but uncommon. Alpine breeding of migratory birds is a feature including branded dotterel, SI pied oystercatcher, black-backed gull and black fronted tern. Waterbirds include grey duck, paradise shelduck and black shag. Introduced birds are numerous and predominate in most habitats. They include blackbird, thrush, green finch, chaffinch and yellowhammer. Gamebirds chukor and Californian quail and white-backed magpie reside in the lower slopes.
Lizards are the most important element in the Central Otago fauna and common gecko, common skink are abundant and widespread. The larger Otago skink and grand skink are rarely found – mostly in Lindis-Hawea areas.
The Cromwell Chafer Beetle
Cromwell Chafer Beetle Reserve
On Christmas Day 1903, John Henry Lewis (1874-1924), a little known early Otago civil engineer with the Central Otago railway works and naturalist, discovered the Cromwell chafer beetle that was later to bear his name Prodontria lewisi.
The 81ha Cromwell chafer reserve is the first in New Zealand (and one of the very few in the world) to be created specifically to protect an insect - the Cromwell Chafer. It was gazetted in 1983 following surveys going back to the late 1960's of fauna and flora likely to be affected by the Upper Clutha hydro-electric power proposals. The reserve is located along Bannockburn Road, adjacent to the Transpower Cromwell Substation. It is managed by the Department of Conservation, who commission scientific studies that add to the body of knowledge of the chafer's lifecycle, ecology and conservation status.
Cromwell Chafer Beetle Reserve
Unique Beetle in a Unique Landscape: The Cromwell Chafer is one of the countries rarest and most confined animals. It evolved in the sandy soils around Cromwell and is now largely restricted to the reserve because its habitat has been destroyed or severely modified elsewhere.
A chunky, flightless beetle reaching 15mm in length, the Cromwell chafer emerges at night during spring to feed on cushion plants and other herbs. By day the adults hide themselves in the upper layers of sand. The larvae, which may survive two years, live deeper underground and feed on the roots of the Raoulia cushion plants, silver tussocks and other grasses. Adults live for only a couple of weeks, but they may appear on the surface from August to January. They are especially active on warmer nights and numbers peak in September-October. The chafers are unevenly distributed across the reserve. In some areas they number several hundred, in other areas only a handful survive.
Duneland Habitat: The chafer's habitat is of special interest to science - a rare example of an inland sand dune system, some 210 metres above sea level. Stable dunes underlie the younger windblown ones, and beneath the sand is a gravel bed - an alluvial terrace formed by ancient rivers. The dunes have been built up over thousands of years from sand brought down the Upper Clutha Valley by countless north-west gales.
Within the stable dunes, where most of the chafer larvae live, are layers of sandy loam enriched by organic material. The last ice age about 15,000 years ago contributed to the dune system.
No glaciers reached this area but the valley floor collected windblown silt and river-borne outwash gravels and other sediments.
In 1990 the reserve was declared a soil site of international importance by the New Zealand Society of Soil Sciences.
Vegetation: Herbs and grasses, notably silver tussock Poa cita, form the natural cover of this area of inland sand dunes. Two species of Raoulia cushion plant, R. australis and the less abundant R. hookeri, are thought to be important to the Cromwell chafer larvae and adults. The rarest plant is the native woodrush Luzula celata, which is regionally rare. This is the only known inland site in Otago. The dynamic nature of these dunes inhibited the establishment of native shrubland or forest over them. Today, introduced herbs and grasses provide much of the vegetative cover, among them pasture species such as sorrel (which chafers have been seen feeding on), browntop and sweet vernal. Flowering plants include Californian poppy, Vipers' bugloss, spur valerian, mallow, stone crop and briar rose.
Visitors are invited to visit the reserve and to read the interpretation plaques located adjacent to Bannockburn Road car park area.
Birds of a feather
Climatic changes over a period of thousands of years aided in more recent times by the hand of man have modified the plant and animal life of the Cromwell area. The Pisa Range was once well forested with the giant totara but fire, either from natural causes or from the operations of moa hunters, removed the forest cover. When all else had rotted away, the tough totara logs remained as a source of firewood for the early settlers and a reminder of another environment. Despite fire, flood and sand storm, many of the native species of bird life survived only to become the victims of species introduced by man. The moa had disappeared long before the arrival of the first settlers while the weka has vanished from the area within the last 60 years. The little owl (Athene noctua) introduced early this century in an effort to control small birds in orchards has flourished to the detriment of the smaller native birds and the rare Cromwell chafer beetle.
Sometimes called the German owl, the little owl is characterised by a whitish face and a white under surface with brown stripes. It walks freely on the ground and during daylight hours can often be seen perched on fence posts or tree stumps.
The rivers and ponds of the Cromwell area provide an ideal environment for ducks. Of these the mallard is the most common. It was introduced to New Zealand in the late 1860's but it did not become well established until the 1930's. It is prized as a game bird and on occasion interbreeds with the native grey duck. Slightly smaller than the mallard, the greyduck is distributed throughout New Zealand inland waters. Smaller still is the neat little grey teal occasionally sighted away from the main waterways.
More at home on the inland lakes, the paradise duck is an occasional visitor to the Cromwell area. The male is the handsome one of the pair; the female's colouring is more subdued with a white head as opposed to the dark of the male. Another lake dweller seen in the Cromwell area is the New Zealand shoveller duck. Its broad, flattened bill acts as a filter as its fossics for food amongst the mud or on the surface water.
The black shag with its seemingly insatiable appetite is the scourge of freshwater fish. Eels up to 60cm in length can disappear down its throat with ease. It is generally seen resting on a branch in solitary state as it digests its latest meal. Although Cromwell is as far from the sea as it is possible to get in the South Island, three types of gulls frequent the area. The black backed gull, the black billed and red billed gulls nest in riverbed colonies. The black fronted tern nests only in the South Island and is seldom seen during the winter months. A riverbed dweller, its staple diet is insects and fish. The South Island pied oyster catcher also nests only in the South Island. Its long, orange bill busily probes the sand and mud for worms and crustaceans and expertly deals with hapless bivalves.
Often seen on the highway making a meal of some unfortunate rabbit, the hawk makes a majestic sight as it flaps out of harm's way from the approaching car. There are two species, the New Zealand harrier and the New Zealand falcon. Both are aggressive in their search for food and do not discriminate between the chicks of native birds or those of domestic poultry.
The white backed magpie was introduced to New Zealand from Australia and has only come as far south as Cromwell within the last 25 years. Another importation from Australia is the dainty silvereye which makes its appearance in suburban gardens during the winter months when snow drives it down from the hills. Bread or fruit left outside will be picked clean by twittering flocks of these small, greenish birds with their silver circled eyes.
The early settlers began introducing European birds from the 1860's, some for sentimental reasons, others in the hope that they would control a real or imagined pest. The blackbird and thrush frequent most gardens as does the occasional starling. Flocks of goldfinch, redpoll and yellow-hammer are a common sight.
This is by no means a complete list of the birds to be seen in the Cromwell area and with a little bit of patience many more may be spotted. It is important to remember that many birds are totally protected and should be left well alone. Information on these species may be obtained at the public library.