The first year of a four-year operation is initially removing cherry trees, sycamores, wilding pines and cotoneasters in the gorge area.
Controlling large, shade-tolerant weed trees will help stop them from squeezing out native species, while the felling of old-man pines will prevent their spread to farmland and other areas outside the gorge.
Environment Canterbury is working on the project with farmers and other landowners, Selwyn District Council, Manawa Energy’s Rakaia Fund and Land Information New Zealand. The Ashburton District Council has also contributed by removing old-man pines.
Over the past year the team has logged more than 1500 hours, dealing with at least 12,000 cherries and sycamores, at a cost of more than $130,000.
A drill-and-fill technique with holes bored into a tree base and filled with chemicals is often being used to prevent drift on to surrounding vegetation.
Leading up to this a drone surveyed the land in autumn to show the team where hazardous bluffs were and, with GPS units, identify dense weed patches, helping to avoid double-ups or areas missed.
"We are in a good place now to plan for operational activities in 2023 and 2024," Selwyn council project leader Andy Spanton said.
"By that time, we should have a clear idea of the further resource required to complete the project."
The next season will likely focus on cotoneasters dominating the Zig Zag site next to the Rakaia Gorge Walkway.
Farmer David Harper is also felling stands of pines as well as restoring wetlands on his property.
He said the Rakaia Gorge held a special place in their hearts.
"We feel very excited that this is just the beginning of looking after this very important place. This will be something that future generations will carry forward."
An ecological assessment of the gorge in 2019 found at least 16 threatened and at-risk native plant species, including Canterbury pink broom and rōhutu/myrtle which are both classified as nationally critical.
