Wilding trees turning brown upstream of the Red Hut Bridge are changing the Tongariro River landscape.

To deal with a proliferation of wilding pines, the Advocates for the Tongariro River, a local community group, have hired a contractor to return the river environment to its original native state.

The trees have been injected with a poison that quickly kills them.

Some trees, such as those immediately beside the public walkway, will be felled for public safety reasons, while the rest will be left to decay and disintegrate, Kim Turia, community relations manager for the department of Conservation, said.

“We will leave the natural ecosystem to manage the recovery of the native species as they do that job better than we can.”

DoC’s Taupo area manager Dave Lumley said the method was efficient so far.

“Even after a short period of time you can already see the benefits of regeneration of the native understory now that the shading canopy created by the large pines has been removed,” he said.

DoC has been working with the Advocates for the Tongariro River for a number of years.

On river banks where native forest re-growth is being encouraged, wildling pines are a pest plant that compete for forest space with native trees and plants but provide no berries or nectar to encourage native bird and insect life.

Pine needles also form a carpet which discourages regeneration of native forest floor species. In areas where native forest does not occur, such as above the bush line, in mineral belts and tussock grasslands, wilding pines can alter natural ecosystems entirely.