Ruapehu pine tree nearly beat

Ruapehu Bulletin, Volume 6, Issue 286, 16 May 1989, Page 10

Ruapehu pine tree nearly beat

• Mount Ruapehu's upper slopes covered in Pinus contorta forest by the end of the century. • The Army's Central North Island training grounds so thick with Pinus contorta that it would be a major fire hazard and useless for training purposes. • The ecological and economic values of the Kaimanawa and Kaweka Forest Parks, including the near-by wilderness areas, totally compromised by contorta's rapid spread.

This is the future scientists painted 25 years ago before government agencies, local authorities and thousands of volunteers began a campaign to stamp out one of this country's fastest spreading nox- , ious weeds - Pinus con- - torta. Department of Conservation Tongariro District conservator Paul Green, who's department is one of almost a dozen agencies fighting contorta, said the prophecy of environmental doom had been turned into a "conservation success story". Today all the mature seed trees have been destroyed and control efforts continue to pull out the remaining juvenile trees. By 1994 the main eradication effort should be complete, with helicopter control sweeps then r;eeded to stamp out the few remaining stands, Mr Green said. The fight has been a hard one, Mr Green said. Contorta is tenacious and trees seed after only five years' growth, with seed ones "exploding" to scatter their seeds upon the wind. Ruapehu covered The seedlings are also prolific. During a 1962 botanical survey up to 121,000 contorta trees were noted per hectare. It was during that survey that scientist Dr I Atkinson concluded contorta would eventually cover Mt Ruapehu's upper slopes. Dr Atkinson believed

that contorta plantations would completely blanket the existing alpine environment by the year 2000. Since 1982 more than $4 million has been poured into contorta's eradication. Government agencies have joined the campaign but, ironically, it was government agencies which were first responsibie for its introduction. Between 1925 and 1935 contorta was planted in the Karioi State Forest after Pinus radiata plantings failed. Contorta proved that it could adapt to the area's climate and in future years was used as wind breaks on land development projects throughout the district. As late as 1967 government agencies were still actively planting contorta, unaware of the economic and ecological damage that was about to occur. Quick spread Once the plantings began, contorta quickly spread. It easily colonized land that was not actively grazed and was tough enough to grow comfortably up to 2000 metres above sea-level. In its early days contorta had strong and vocal allies, Mr Green said. Forestry professionals saw economic value in its rapid spread and it took years before they accepted it was a fast distributing threat with little economic value. Senior Army officers also approved of contorta on their training grounds at first. They

saw advantages in its ground cover, shelter and shade for exercise purposes. When it became obvious that thick contorta forests would destroy the land's training value, they too decided eradication was necessary. In 1982 a Pinus contorta co-ordinating committee was formed to fight the problem. Initiated by the Department of Lands and Survey, concerned at the effect on Tongariro National Park's ecology, the committee was made up of the Waimarino, Taumaranui, Rangatikei and Taupo noxious plants authorities, Department of Lands and Survey, R angi tikei - W ang anui Catchment Board, Ministry of Defence and New Zealand Forest Service representatives. That year the authorities spent $327,000 on contorta control, an effort which was to escalate in the years to come. Volunteers Their efforts were reinforced by thousands of volunteers from tramping clubs, conser-

vation organisations and schools who, in 1962, began to create a buffer zone within Tongariro National Park. Since then volunteer work too h'as escalated. Between 1982 and 1986 22,464 volunteer hours were spent on contorta control. Last year 297 people from 19 organisations cleared 695 hectares of medium to low density contorta country adjoining the park. "These groups have always been enthusiastic and have never lost their optimism," Mr Green said. "As they have succeeded in controlling contorta within the Tongariro National park they have moved on to adjacent Maori and defence land." Since the early 1970's the work of volunteers within the park has been supported by regular helicopter sweeps which spot areas of contorta infestation and transport staff in to eradicate it. During high altitude control work, up to 2000 metres above sea level, helicopters have proved to be very

economic, Mr Green said. After 25 years of effort, which has steadily increased to include input from the district's central government and local government agencies, Pinus contorta is under control. "It is one of the few weed control programmes which can make such a claim," Mr Green said. "The end is now in sight," he said. "By 1994 we should have the main Pinus contorta population eradicated. Then its a matter of continued maintenance and helicopter control on into the future." Thanks to a concerned and intensive effort, the prophecies have not come true. The Army continues its exercises on relatively open country and the indigenous forests of Tongariro National park, Kaimanawa Forest Park and the Kaweka Forest park remain protected from invasion. Contorta, the weed which once threatened to spread through the Central North Island, has been checked, says Paul Green.