Preserving the Te Anau wetlands

Forest and Bird, Volume 14, Issue 6, 1 May 1983, Page 37

Preserving the Te Anau wetlands

By

Department of Lands and Survey

David Gregorie,

AS BUS-LOADS of tourists thunder along the highway between Lake Manapouri and Lake Te Anau few of them would guess that just out of Sight to the east is one of the finest examples of a string bog outside the Boreal peatlands of the Northern Hemisphere.

THE FIRST IMPRESSION that any visitor to the Te Anau basin must get is of thousands of hectares of well-tended farm land. There is little to suggest that hidden behind the rolling pastures there are some 3000 ha of wetlands and forest remnants of considerable geomorphic, biological, and palaeobotanical interest. The Department of Lands and Survey, which is responsible for farm development and settlement in the area, is excluding from development a number of bogs, swamps, stream berms, and other wetlands and patches of _lessmodified bush and _= scrub. These areas are important scientifically for their unique or unusual plants and plantassociations, for the opportunity they give to study peat samples dating back for several thousand years, and for the secure habitat they offer for breeding waterfowl and other wildlife. Managed as reserves At present these areas are being fenced off and managed as reserves. When the surrounding farm units are surveyed for settlement the reserved areas will themselves be surveyed and gazetted as wildlife, nature, or other reserves. The Kepler String Bog, also known as the Old Channel Bog, occupies the ancient channel of the Waiau River between banks of old glacial moraine. String bogs have a characteristic pattern of pools elongated at right angles to the main line of drainage and

stepped up the slope like a staircase. The Kepler Bog drains into Home Creek, itself to be set aside as a reserve, and thence into Lake Manapouri. The complex vegetation pattern includes wire-rush (Empodisma minus), turpentine plant (Dracophylum oliveri), sedge (Baumea rubiginosa), and the mosses (Eucamptodon inflatus, Campylopus kirkii, and Sphagnum falcatulum). The impressive pool system near the centre is divided by islands and isthmuses supporting bog pines (Dacrydium bidwillii, D. intermedium, and D._ laxifolium), which have probably been protected by their isolation from the fires that have swept the district since pre-European times and which severely modified the previous vegetation pattern. A recent survey by the Wildlife Service recorded grey and paradise ducks, Canada geese, marsh crakes, bitterns, fernbirds, and black-backed gulls nesting around the pools. The peat is about 6 m deep, and borings taken for pollen and macrofossil analysis have provided a valuable record of the post-glacial history of the Surrounding vegetation. Noel Hellyer, assistant director (survey) in the Wildlife Service, describes the Riverslea Farm Development Block,

south of the Kepler String Bog, as being an _ excellent example of land management. A wildlife reserve has already been established on the block. **Bruce Newlands, the farm manager, has done an _ incredible amount to protect wildlife habitat in the area,’’ he says. Dome mire East of the main road north of the Te Anau township, but screened from it by the intervening forest and scrub, lies one of the best specimens of a dome mire anywhere in New Zealand. Known simply as ‘‘Dome Mire’’, itis a classic raised bog with a domed centre and a concentric pattern of ponds, similar to bogs found in the vast peatlands of northern Scandinavia, Siberia, Alaska, and Canada. Like all true bogs, it depends largely on rainfall for its water supply, and the acidic, infertile water supports little other than the normal bog plant species found in the district. The main interest for the botanist lies in the margins. The north-western and northeastern . edges. ofthe «bog Support stands of silver pine (Dacrydium colensoi), which is not found elsewhere east of the main divide. Subfossil remains suggest that it was once widespread in the Te Anau basin. A small orchid (Acianthus fornicatus) has been found in a fen just south of Dome Mire, which has considerably extended its known range. Black-billed gulls, pied stilts,

and fernbirds nest around the ponds. To the east of Dome Mire lies the Dale Development Block, about 30 percent of which will be excluded from pastoral farming and set aside in reserves. These include Dale Forest and Lake Otter, berm areas along the banks of the Whitestone and Upukerora Rivers, and another small reserve at present managed by the Wildlife Service. Luxuriant cover Kakapo Swamp, close to the main road about 6 km east of Te Anau, is a prime waterfowl breeding area and contains luxuriant cover of flax, niggerhead, and abundant watercress. The water level has been raised and the swamp area extended to increase the breeding space available to birds. The curiously named Dawson City Swamp, an interesting fen dominated by the sedge Carex diandra, and the Wilderness Lagoon, both in the Wilderness Road area, have also had their water levels raised by weirs to add to their potential as waterfowl breeding areas. Land development has been seen by some as a menace to the remaining wetlands of the Te Anau basin because of the burning off and the drainage of swamps and bogs associated with it. But devastating fires, as we have seen, are nothing new. They have swept the area for centuries. The clearing of vulnerable dry scrub and _ its replacement by pasture plants should lessen the chances of widespread fire in the future. The Kepler String Bog and the Dome Mire, both regarded as wetlands of international significance, have been excluded from development, and any interference with their drainage patterns is _ being avoided. These and_ several

other small wetlands have been set aside as potential reserves, and the swamps mentioned above have been extended and enhanced to improve their carrying capacity for breeding water birds.

‘‘Lands and Survey policy is to strike as equitable a balance as possible between the various conflicting land-use options for the basin,’’ says Bing Lucas, the department’s director-general. ey