MPI says a quarter of New Zealand would be covered in wilding conifers if controls were not in place. Photo / Bevan Conley
By Monique Steele of RNZ
The fight to stop the remarkably rapid spread of wilding conifer pine trees continues, as Southland officials are warning that the pines have caused a land-use and biosecurity crisis for the region.
Around 2 million hectares of New Zealand were covered by wilding pines, like common offenders Pinus contorta and Douglas fir, and untreated areas expanded at a rate of about 5% each year.
Pine seeds could travel tens of kilometres by wind and grow easily, posing a difficult task for teams trying to stamp out infestations.
A quarter of New Zealand would be covered in the unwanted pines without controls, according to the Ministry for Primary Industries website.
In late July, the Government announced an extra $3 million over three years for wilding pines controls in Molesworth and Mackenzie Basin areas, funded by the International Visitor Levy, adding to the $12m already allocated this financial year.
Industry group Federated Farmers’ pest animal and weed spokesman, Richard Dawkins, said wilding pines posed an “ecological crisis” – and while the funding was welcomed, it fell short of what was needed.
“The battle against wilding conifers is being lost,” he said.
“Some funding has been allocated over the years, but it’s been patchy and nowhere near enough to tackle the problem properly.”
Southland Regional Council councillors were told this week the spread of Douglas fir in particular was accelerating across the region, and current investment and control methods were “inadequate” to keep pace with the scale of spread.
Environment Southland’s report author warned that the cost of controls increased exponentially over time, once trees matured and seeded.
“Without further intervention, vast areas of northern Southland could be overtaken within 30 years, resulting in irreversible environmental and economic loss,” it said.
“Wilding conifers are spreading at a scale and speed that outpaces current control budgets and operational efforts can contain.”
Biosecurity New Zealand co-ordinated the National Wilding Conifer Control Programme with landowners, industry groups and councils.
Manager Sherman Smith said it was working to manage a dozen problematic species across 42 areas nationwide that threatened biodiversity.
“They form a monoculture of these unwanted and pretty much useless trees,” Smith said.
“They shade out all the native plants and animals, they increase the fire risk warning because wilding pines are quite flammable and there are no fire breaks, so they can cause some significant increase in fire risk.
“They can also reduce the amount of water that is going into streams, particularly in those drier areas of the country, which has some flow-on effects in terms of irrigation and hydro generation.”
Smith said they also had effects for tourism.
“Obviously, it has quite a landscape impact; it cloaks a lot of the iconic New Zealand areas in these forests that are exotic, so collectively those impacts are worth billions [in costs] to New Zealand if we allow these things to keep spreading.”
He said the programme prioritised areas, then developed plans with regional councils and landowners that contractors helped implement.
“I think at peak, we had about 500 contractors on the ground.
“It’s a little bit less than that at the moment, obviously with their funding being a little bit lower than it was at peak.”
More than $150m of government money has been committed to the programme since it was launched in 2016, with another $33m from landowners and communities.
The Government established a baseline funding model of $10m in 2023/2024, excluding top-ups, which deferred some work and prompted concerns among Southland officials.
Smith said there had been some success in control areas where seeding trees were removed, then seedlings were controlled in three-yearly cycles before they coned.
“We’ve got some really good success stories that are getting to the end of the journey and really at a point that we can hand back the management to the landowner to manage as part of their day-to-day farming operations or land management work.”
However, he said there was more work to do.
“There are still some big challenges in front of us,” he said.
“We’ve done the first round of control across about three-quarters of our known infestations, so there’s a quarter out there that we haven’t started into yet, and obviously, the gains that we have made, we’ve got to keep on that maintenance to lock in those benefits that we’ve achieved.”
Smith asked farmers to check that there were no “problem-tree species” in their shelter belts and small woodlots, which were two major sources of the trees.
– RNZ