Ten years ago, South Marlborough Landscape Restoration Trust was established to help mitigate the spread of wilding conifers in the region. These invasive trees are now threatening a large area across the top of the South and spreading at an unprecedented rate, with significant environmental and economic implications.
The threat centres on a 50,000-hectare catchment at the head of the Wairau Valley, where there are approximately 20,000 hectares of dense conifers, spreading at roughly 400 hectares annually. Beyond the catchment boundaries, seed dispersal from the Branch Leatham has affected an estimated 180,000 hectares, including 50,000 hectares in the Awatere sector and another 50,000 hectares on Molesworth Station.
“The Branch Leatham has always been at the heart of this concern because it’s a ticking time bomb of compounding seed-rain dispersal,” says Mr Oswald, Chair of the Trust. “I sincerely believe it is the worst manmade environmental disaster that New Zealand has ever faced.”
Unlike previous environmental challenges such as rabbit or deer introductions, which have been successfully managed, the conifer invasion threatens permanent landscape change. One of the primary invasive species, Douglas fir, is shade-tolerant and capable of eliminating native beech forests while establishing above the native bush tree line at elevations approaching 3,000 metres.
Mr Oswald says the invasion has significant implications for tourism, agriculture, and biodiversity. “The Marlborough tramping club has been up there with chainsaws to open up tracks that are no longer passable; you can’t push your way through the dense swards of contorta pine trees,” says Mr Oswald. “As well as tourism, the economic impact extends to Marlborough’s wine industry, due to reduced water yield, and the merino fine wool industry, due to loss of grazing areas.”
South Marlborough is also one of five centres in New Zealand where unique species, plants, or animals are found only in that specific geographic area and nowhere else in the world. Trust Coordinator Ket Bradshaw says many of these face habitat elimination as the invasive conifers take over the environment.
“At least 29 nationally threatened or at-risk plants species occur in the Branch Leatham, of which nine are endemic to South Marlborough,” says Ms Bradshaw. “If we continue the way we are, these trees will replace the indigenous biodiversity and tussock in the mountain landscapes of South Marlborough, all the way to Kaikōura.”
The Trust is supported by over 60 volunteers. To date, the volunteer programme has eliminated 50,000 trees from remote alpine basins, including the Lost Valley, which has no road access and requires a seven-hour walk to reach. The Trust also organises volunteer days and educational presentations to school and community groups.
Much of what the Trust has achieved over the last three years has been supported by funding of $450,000 from Rātā Foundation. The funding enabled the Trust to develop the plan to understand how the issue could be addressed, aerial control across 10,000 hectares in the western Branch Leatham sector called the Raglan Range, and the volunteer work in the Lost Valley demonstrating the feasibility of large-scale intervention.
Rātā Foundation Head of Community Investment Kate Sclater says: “The South Marlborough Landscape Restoration Trust’s mission aligns closely with our aim to support environmental resilience through collaborative approaches at a landscape-scale.
“We have seen firsthand the positive impact that investment in empowering local people to find solutions is having. The efforts of volunteers to eradicate wilding pines has resulted in the return of native plants in some areas, but this is only the beginning of the long-term approach that is required to protect the indigenous biodiversity of the area. With a peer-reviewed plan now in place, there is a course of action on tackling this challenge.”
The 10-year feasibility plan shows that $10 million annually could address the issue, says Mr Oswald. “We have an opportunity now with the 10-year plan that shows that for $10 million a year for the next 10 years we can control the worst area in New Zealand. If we do that, the rest of it will fall into place. The Sapere Report, commissioned by MPI, shows that controlling wilding conifers returns $38 for every dollar spent – the highest return of any biosecurity issue in New Zealand. If we act now, we can help preserve the top of the South for future generations.
“We’re indebted to Rātā Foundation for giving this funding in the last three years because it has allowed us to upscale what we were doing. Without Rātā, we would never have got to this level.”
About Rātā Foundation: Rātā Foundation is the South Island’s most significant community investment fund, managing a pūtea (fund) of around $700 million. This enables Rātā to invest around $25 million per annum into its funding regions of Canterbury, Nelson, Marlborough and the Chatham Islands. Since its inception in 1988, Rātā has invested over $600 million through community investment programmes to empower people to thrive.