Combating the spread of wilding pines around Queenstown Lakes will be an intergenerational fight, where standing still means going backwards.
Whakatipu Wilding Control Group (WCG) has led the fight in Queenstown for 16 years and its chairman Grant Hensman says the landscapes would look very different now without the years of hard work that's already gone in.
"If council hadn't had the vision to set this up ... it would all be much greener by now. Cecil Peak would be 50% coverage, the Remarkables not far behind.
"We remove around 6,000 trees a year off Cecil Peak and more than 10,000 off the Remarkables. They’re spreading across the lake from the forests on the Queenstown side.”
In 2025 alone, WCG removed 96,550 pest trees, with 605 volunteers carrying out more than 5000 hours of on the ground work. Since 2009, hundreds of thousands of trees and saplings have been removed and more than $26 million has been spent on tackling the invasive species.
And the battle is about far more than aesthetics says Grant, son of Skyline Enterprises founder Hylton Hensman and a director of the Queenstown tourism giant.
Wilding conifers, including species like Douglas fir, contorta pine and larch, spread by wind-borne seed and form dense, closed-canopy forests. Left unchecked, they replace native beech stands, alpine herb fields and golden tussock grasslands.
These monoculture forests reduce habitat for indigenous species of flora and fauna. They also draw significant amounts of water from catchments, intercepting rainfall, increasing evaporation, reducing the water that feeds rivers and aquifers. In the country powered by hydroelectric dams, that has a significant cost.
And they present a fire risk. A vast stretch of wilding pine forested slopes above Queenstown is designated a fire red zone, from Rat Point though Fernhill, and all the way on to Arthurs Point. Open fires and fireworks are banned year-round. As the 2020 Lake Ōhau wildfire shows, should a wildfire take hold beyond control, the outcome could be catastrophic.
"When you’ve got trees covering inaccessible country, the risk increases dramatically - particularly in a place like Queenstown," Grant says.
Back in December, an Ōhau village resident, representing the Ōhau Conservation Trust, gave a moving presentation at the annual Wilding Pine Network conference, held in Twizel. WPN provides national coordination, advocacy and technical guidance for community groups and agencies managing wilding conifers across the country, including WCG, Wānaka's Upper Clutha Wilding Tree Group and the Central Otago Wilding Conifer Control Group.
Grant says the conference, which included field trips into Mackenzie Country, showed some of the consequences of not winning the battle, and also the need for collective action.
"You can't win in Queenstown or Wānaka if you don't win in Mackenzie Basin,” he says. “Seed spread knows no boundaries … if you lose one area, ultimately you’ll get surrounded and overwhelmed in time."
That applies locally as well. While the commercial Coronet Forest near Arrowtown has recently been felled, replaced with the new Project Tohu trail network and regenerative native planting, the red zone trees remain, along with those on Queenstown Hill and Queenstown Gardens.
Queenstown Lakes District Council has approved regenerative projects for both areas, including the Te Tapunui Queenstown Hill Restoration Management Plan 2025. Mature non-native forests across the region will all need to be replaced over time.
"Otherwise, you're bailing out the boat every year, forever. Eventually people get tired of putting money into what feels like a never-ending task.
"At Cecil Peak, we have to spend about $100,000 a year just to hold the line. While we’re spending that money there, we’re not spending it somewhere else. The trees creep up on you. It's not about denuding these landscapes, it's about having the right trees. Replace the problem species with ones that don't create these issues."
WCG uses a mix of methods - ground crews, drill-and-fill herbicide injection, targeted helicopter-based application, and, in dense inaccessible stands, aerial foliar spraying as a last resort. All work is GPS-mapped to guide future priorities.
But the decrease in Government funding for wilding control across New Zealand is a real issue.
The country is going backwards in this space. We simply won't win unless funding levels are increased, so we'll continue to lobby central government."
Independent analysis has shown huge 96:1 cost-to-benefit ratios of tackling wilding pines, particularly when you factor in the draw on water.
"In the Mackenzie Basin there are seven power schemes producing around 1,650 megawatts of electricity. Studies show wilding pines can reduce water yield by 16% and 81%. Even taking a conservative 20% reduction, that's about 330 megawatts - roughly $289m a year in lost generation."
Locally, projections show the Mataura River could effectively run dry, if the spread continues in the Upper Mataura near Kingston.
"These trees draw significant amounts of water.”
Grant says the work isn't a 'nice-to-have'. It's an investment to avoid handing a much larger bill to the next generation.
“If you could freeze the landscape as it is today, we’d probably all be happy. But doing nothing means change. The trees will continue to spread and eventually overwhelm everything.”
WCG's programme continues across the basin. One of the major projects this year is tackling Mugo Pine in Muddy Creek above Gibbston; a serious problem species which has no effective chemical control.
"We're putting about half a million dollars into that project alone."
There are plenty of ways for local businesses to get involved, from WCG's Adopt a Plot scheme to volunteer days, membership, donations and ongoing sponsorship.
Skyline, QEII National Trust and Todd & Walker Law and Ecofund are backers, while WCG is also supported by stakeholders such as Queenstown Lake District Council, ORC and LINZ. Key partners include the Wilding Pine Network and The National Wilding Conifer Control Programme, and most major landowners.
Visit whakatipuwilding.co.nz for more information.