Ruataniwha protecting a natural remnant of the Mackenzie country

Forest and Bird, Volume 23, Issue 1, 1 February 1992, Page 29

Ruataniwha protecting a natural remnant of the Mackenzie country

Mike Harding

Today the Mackenzie country evokes images of a broad and somewhat barren plain surrounded by distant mountains. But take a closer look and the real diversity of this massive intermontane basin

reveals itself

examines one part that should be protected.

UCKED AWAY from the public gaze in the Mackenzie Basin are miles of rivers and their braided deltas. These areas contain rare wading birds like the black stilt, native tussock grasslands, small forest patches nestling in sheltered gullies and spectacular moraines, terraces and eroding loess cliffs — a legacy of the glaciers that scoured the basin only a few thousand years ago. Ruataniwha is home to some of these curiosities. It is a tract of land whose future hangs in the balance. Covering the steep slopes at the southern end of the Ben Ohau Range behind Twizel it contains woodlands of Hall’s totara, native shrublands and spectacular tall tussock grasslands. The sparse totara forest is one of the few remnants of the woodlands

that once covered the drier slopes throughout South Canterbury and North Otago. The forest stretches across 500 hectares, in two main patches, above the shores of Lake Ohau over broad boulder slopes. It is crowned by the bluffs of the 1522-metre peak of Ben Ohau and flanked by native tall tussock grassland. All of this, including the basin of Gretas Stream to the north, lies within Ruataniwha station — a pastoral run of about 3,600 hectares presently managed by Landcorp on behalf of Electricorp. O SPECIAL 1s the Hall’s totara stand, as a relic of some of the driest forest in the country, that the area was recommended for protection as a scientific reserve back in 1976. This plea, contained in a joint Lands and Survey

Ruataniwha

Department, Forest Service and DSIR report, noted that because of the vigorous regeneration of Hall’s totara the area could become "‘an outstanding scientific and scenic attraction" and recommended that "‘an earnest effort should be made to secure this area". One of the key features of the proposed reserve is its diversity — lake margins, stable colluvial fans, screes, boulder slopes, outcrops and bluffs — a microcosm of the surrounding ranges. These varied habitats support an extensive range of plants and animals. The lower slopes have an almost complete low forest cover of broadleaf, kowhai, totara and hardwood shrubs providing food for bellbirds, tuis and pigeons. Numerous common skink and the endemic Mackenzie Basin ground beetle, Megadromus alternus, earned the area the status of a Site of Special Wildlife Interest from the Wildlife Service in 1978. Kowhai and mountain ribbonwood are clustered higher up the slopes where, with the totara, they have escaped earlier fires. Shrubland surrounds most of the forested areas and contains a rich association of dry-climate species. At higher altitudes, the slopes are dominated by tall Chionochloa rigida grassland. Dwarf and large-leaved mistletoe (Korthalsella clavata and Tupeia antarctica) are unusually abundant. The slopes give a spectacular backdrop to Lake Ohau, an increasingly popular recreation and tourist area. It is not surprising that the Protected Natural Areas survey team in 1984 endorsed and extended the earlier reserve proposal. In a wider survey, they also identified other important features on Ruataniwha station as priority areas for protection. The summit ridges and basins of the Ben Ohau Range contain some of the best remaining tall tussock (Chionochloa rigida) grasslands in the district. The PNA team identified an 800hectare area in upper Gretas Stream, mostly on the adjoining Omahau run, as an important area for protection. In lower Gretas Stream an area of mountain beech forest, a remnant of a formerly more widespread forest, was also recommended for protection. It is an intact and reasonably well buffered forest containing abundant red-flowering mistletoe, Peraxilla tetrapetala. As well as the key representative natural areas identified by the PNA team, there are other parts of the run worthy of protection. The moister south-facing slopes, above the totara remnants, have a healthy cover of tall and fescue tussock with a rich mix of intertussock herbs. In the drier parts of the Gretas Stream catchment an extensive metre-high Chionochloa rigida grassland occupies the stony slopes while red tussock occurs in the damp

hollows. Other features are shrublands with kowhai trees surrounding the lower bluffs, and native falcon. A major problem, however, is introduced hawkweed (Hieracium spp.)which grows between the tussocks and threatens the integrity of the grassland. Land capability mapping identifies all the higher areas as unsuitable for grazing. This part of Ruataniwha station supports less than one sheep per hectare for only a few weeks in summer and it is debatable whether it can sustain grazing in the long term. In fact the most productive parts of the property for grazing are the lower slopes where oversowing and topdressing has been carried out, and the open flats between the range and Twizel where rabbit control has recently been so successful.

ESPITE RECOGNITION of the important conservation values of the area, formal protection for this scenic and scientific gem remains elusive. The proposal for the totara reserve has been lurking in government files for over 15 years, for so long in fact that its protection seemed a foregone conclusion. However, last year Forest and Bird learned that the whole of the property was to pass to Landcorp who could sell this natural gem on the open market, with covenants over conservation areas. The allocation of an important natural area with negligible production values to Landcorp instead of the Department of Conservation would be a scandal and contrary to the criteria for the disposal of surplus crown lands. The problem has its roots in the 1960s

when Ruataniwha station was transferred to the old Electricity Division to enable construction of the upper Waitaki hydro electricity scheme. With the creation of the State Owned Enterprises in 1987 the whole of the run passed to Electricorp with the agreement that all areas not directly required for electricity generation would later be reallocated to the Department of Conservation or Landcorp, depending upon their predominant values. Forest and Bird believes that the property should now be assessed under the agreed criteria for the allocation of surplus Crown lands. It is clear that much of the area has outstanding conservation values and great recreational potential. A four-wheel-drive track climbs right to the summit of the range providing access and the opportunity to establish a first class tourist safari with magnificent views of the Mackenzie Basin and Southern Alps. There are presently few protected areas in the Ben Ohau Ecological District so protection of any forest remnants, shrublands and intact tussock grasslands assumes a greater importance. Ruataniwha represents an opportunity to protect a wide range of the original vegetation types of the area in one contiguous reserve. Areas of highly modified grassland and the productive pasture on the Twizel flats could pass to Landcorp for farming and the remaining areas, containing high natural values — about 1000 hectares or less than a third of the station

— should be vested with the Department of Conservation as Ruataniwha Reserve. There is already broad agreement about the protection of key areas. The proposed totara reserve has been fenced and destocked for several years and there is no grazing potential in the beech forest remnant in Gretas Stream. Reservation of the grasslands high on the range would provide an opportunity to remedy the critical lack of protection for the native tall tussock communities that once covered large parts of the South Island high country. As tussock grasslands continue to be eliminated by agricultural development, effective reserves are desperately needed to protect the remnants and to monitor the effects of pastoralism. A Ruataniwha Reserve would be of national significance and would provide sustainable recreation and tourism opportunities for Twizel. These important relics of the original vegetation and the spectacular scenic backdrop to Lake Ohau deserve protection now. References Espie P.R. et al. 1984. Mackenzie Ecological Region, Report for the Protected Natural Areas Programme. Department of Lands and Survey. Molloy B.P.J., Hodder R.A.C. and Cowie D. 1976. Joint report: Ruataniwha Reserve — Mackenzie Basin. Department of Lands and Survey, N.Z. Forest Service, DSIR Botany Division. Mike Harding is a field officer for Forest and Bird.