Island forming on Ruapehu flanks to provide sanctuary

Ruapehu Bulletin, Volume 14, Issue 679, 25 March 1997, Page 9

Island forming on Ruapehu flanks to provide sanctuary

An island is forming on the flanks of Mt Ruapehu, not born out of the eruptions, but from a desire by local Maori and Department of Conservation staff to preserve some of the Central North Island' s natural heritage. The Rangataua Forest Mainland Island will be a sanctuary for flora and fauna that is native to the southern slopes of the volcano. It is to be a joint project with an intensive management plan worked out between the Ngati Rangi Trust and the Department of Conservation. But Ngati Rangi are quick to point out that the forest will not be locked up to hunters, which is a concern that has been expressed. Ngati Rangi spokesman Ross Wallis said hunting was good as it was a vital tool in keeping feral deer and pigs under control and limiting the vegetation destruction. The mainland island concept has been applied to other areas in the country where an area has special values and where ordinary management won't help. The core area of the Rangataua Sanctuary will be about 1600 hectares around the Lake Rotokura Ecological Reserve (Karioi Lakes) and on the ancient Rangataua lava flow, which is the biggest forested lava flow in New Zealand. It aims to protect the beech forest ecosystem and several bird, plant, reptile and invertebrate species. It also aims to protect the cultural values of the area that are special to the local iwi, Ngati Rangi, hence the trust' s involvement. Having "an altitudinal sequence that is unique in the region", as well as the unusual lava flow landform has led the DSIR and then DoC to identify the area as having high habitat value. The ancient beech forest survived the Taupo eruption when all else around was flattened partly due to the shadow of Ruapehu and mostly due to the deep valleys of the lava flow system which shielded much of the forest and deflected the blast, 2000 years ago. To kick off the project two Hawaiian field biologists, Dawn Holmes and Chris Haywood have spent the last four months on a comprehensive study of the area doing a flora and fauna stock take. The pair have done similar work on the Hawaiian islands where very similar problems threaten several species of birds. The data they have gathered at Rangataua will be used to formulate a management plan and will also be the base level by which the success of future protection strategies can be measured.

Their study involved marking out 74 plots in the forest on a grid, 500 metres apart, across the whole of the core area of the forest. Inside these plots every plant species and their quantity was noted and this data extrapolated o ver the whole forest to estimate the density of various plants. Systematic bird counts were also done and the results recorded. The biggest population was the chaffinch, followed by the blackbird. "Birds tend to be a good indicator of a forest' s health and they are easy to monitor," said Mr Hayward. Deer and pig sign were also noted, with 50 per cent of the plots showing deer sign and 19 per cent showing deer droppings, indicating that the deer population was locally high, with some heavy grazing noted. Also measured, through a system of trapping, was the pest population, looking at stoats, rats and possums. Rare birds found by the pair include kaka, kakariki, robin, dabchick and New Zealand falcon. In another study not carried out by the pair, kiwi were found at higher altitudes on the lava flow. Next in the process will be the formulation of a feasibility study on the concept of setting up a core area of the forest for active management with the long term view of protecting the whole forest sequence up the mountain side.