In response to safety concerns regarding standing dead, dying, and leaning trees along the Ohakune Mountain Road, a comprehensive inspection and tree maintenance project has been successfully carried out.

Executive Manager Infrastructure Vini Dutra said that following identification of the potential risks these trees posed to road users, a thorough inspection was conducted, leading to a collaborative effort among stakeholder organisations and experts to ensure the safety of the road.

“The inspection, conducted by a team consisting of representatives from GHD, Ruapehu Alpine Lifts, the Department of Conservation, Uenuku Charitable Trust, and Ngāti Rangi, identified 19 trees across thirteen sites that required further investigation.

A Senior Ecologist from Singers Ecological conducted a thorough visual inspection of each tree to assess their health, epiphytic species, and potential bat or cavity nesting bird habitats. The assessment confirmed the need for cutting down 15 trees, pruning or topping 3 trees, and allowing one tree to fall naturally. Additionally, recommendations were made regarding the relocation of epiphytic plants to ensure their continued growth.

To minimize environmental impact, inspections were conducted in the areas where the cut trees would fall or where fallen remains were to be removed. This was done to identify any significant tree species that might be affected by the project. The ecological assessment helped determine appropriate courses of action while considering the preservation of the surrounding ecosystem.

During the inspection process, no bat roosting cavities were identified, and it was advised that the works should take place between late April and early June to avoid disturbing bird roosting during the season.”

Mr Dutra noted that throughout the operation, there was strict adherence to established protocols including environmental regulations and the cleaning of vehicles and equipment.

As the road runs adjacent to the Tongariro National Park no material could be removed from the mountain. Instead, all cut trunks and mulched branches were disposed of in existing disturbed areas and forest margins located next to the road.

Over time, these materials will decompose, contributing to the duff layer on the road shoulders and under the forest canopy. Furthermore, they will serve as a valuable food source for native insects and birds.

All vehicle and equipment were cleaned to prevent the introduction of unwanted plant pests into the Tongariro National Park.”

Mr Dutra added that the hazardous tree removal was carried out utilizing a specialised digger with grapple saw, ensuring controlled felling of trees and branches and minimising the impact on surrounding areas.

This is the first time that the felling of trees as preventative maintenance has been undertaken and it is anticipated that it will be several years before works of a similar nature is required,” he said.

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