Trees under management for carbon
Tonnes of carbon dioxide removed from the atmosphere to date

From site selection and understanding the local ecosystem, to pest and predator control and targeted thinning, New Zealand Carbon Farming’s (NZCF) multi-million-dollar active management programme is designed to create the ideal environment for a flourishing, biodiverse native forest.

Building on over 50 years of research into the process of native transition, NZCF is drawing on a range of expertise in forest management, ecology, pest control and site analysis to tailor its regeneration initiative to sites across the organisation’s 65,000-hectare conservation estate spread throughout Aotearoa.

Environmental consultant and chair of the Regeneration Independent Advisory Group (RIAG) Richard Thompson says the aim of the programme is to create a mature, structurally sound environment with the different layers you’d expect to see in a biodiverse forest.

To do so, he says, site selection is vital. “You’ve got to think about things like the geography of the area, the climate, whether there are native trees in the vicinity,” says Richard. “So any time a property is considered, all of those physical characteristics are considered, and they’re built into a management plan for establishing the transition.”

NZCF Native Forest advisor Matt Upton says as part of that plan the team will assess native bush areas in the region, to determine which species will perform best in each location.

“Then from there we can determine what we might need to bring in ourselves to actively introduce species that might not be there naturally,” says Matt. “We’ve planted just under 300,000 native seedlings over the past three years – adding to the 15 million native trees we currently manage within our estate.”

Within each forest, the fast-growing exotic trees act as a nurse crop for the native species.

“The exotics can help provide the right light conditions for the seedlings,” says Richard. “Some don’t mind being planted into open ground and full light, and in that situation, we are recommending they get planted at the same time as the pines. That will allow us to get those big emergent conifers, like totora and kahikatea, to get up and away as quickly as possible.”

“Then there are the plants, like rimu, that need shelter from wind as they are getting established. Other native trees have evolved to grow in low-light conditions under the forest canopy, and so they need some protection from the harsh sunlight and from competition from grass.”

The exotic trees, while sequestering large amounts carbon dioxide from the atmosphere – one tonne every 13 seconds across the NZCF conservation estate – also provide shelter and shade for the growing indigenous seedlings, until they are removed from the forest canopy to make space and light for the regenerating natives.

“That’s a process that will take time and it requires intervention, monitoring and management as you see what’s happening in the forest,” says Richard. “The work that they’re doing is aligned very much to the actual characteristics of what’s happening on the ground, but at a more rapid level.”

The process of removing an exotic tree creates a lightwell, which allows an area of light into the forest floor to reflect the needs of different species. NZCF has been undertaking extensive trials across a range of its forests to determine the best size, shape and location of lightwells to support a wide range of native growth in the forest understory.

“Typically when a gap is created, there’s a gradient of light,” says Matt. “So right in the centre there’s quite a lot of light and as you move out into the surrounding forest, there’s less. What we’ll find is that some species like the centre of the gap more than the edge. And from there we can determine where the best spot is for a particular species to plant.”

The distance between these plantings – or seed islands for the active regeneration process – is partly determined by the distance a native bird will fly prior to releasing a seed in its droppings.

“A seed island’s purpose is to quickly get some trees established that will provide seeds for birds as well as those native trees that spread their seeds by being windblown,” says Richard.

“A lot of native trees get spread and established by birds eating fruit and then as the fruit goes through the digestive system that eventually comes out as in a dropping somewhere and that seed will then establish. You have to take into account things like the retention time within a bird’s digestive system and how far the bird can fly in that time. And that gives you a guide for how far apart your seed islands need to be.”

Making the forest a welcoming and safe environment for Aotearoa’s native birds is also an important focus of NZCF’s predator control programme.

NZCF Pest Animal Eradication manager Shaun Gifford says targeting the predators – rats, stoats, weasels, hedgehogs and possums – that eat native birds and their eggs has increased in importance for the organisation, as the regeneration programme has progressed.

“We’ve eradicated over 3800 predator animals from our estate,” says Shaun. “We expecting to see a big spike in those numbers as our predator control programme increases, due to the introduction of the A220.”

The A220 is an automatic resetting, multi-species trap developed by innovative local company NZ AutoTraps. In mid-2023 NZCF invested in a 50 percent share of the company in order to support its growth and introduce more of the traps across its estate.

“If we don’t have those birds, in turn that seed source doesn’t get spread and that obviously affects our biodiversity,” says Shaun.

The other side of the programme, in which NZCF invests over $1.2 million per annum, is the removal of browsing ungulates, like feral goats and deer.

“The hoofed animals feed and predate on the small regenerative native plants, as well on our young pine trees that we established,” says Shaun. “Part of our role is to control their numbers, which is a big factor in getting that regenerative native growth through our nurse crop.”

The pests require constant management from a team of professional hunters, using the latest technology, from GPS systems and drones to locate, map and track the pests, to night vision and thermal hunting gear.

“We’ve usually got 20 contractors that essentially work full time doing 10-days on, four-days off stints, throughout our estates, says Shaun. “We’ve got about 70 forests in our estate around New Zealand that currently have pest management on them – so it’s a fair bit of country.”

“We also offer our neighbours a buffer agreement. We’re very strict in staying on our property for the pest eradication programme, but if our neighbours agree, we can extend the programme onto their property, which helps suppress the pest population and prevent reinvasion.”

Matt says the pest and predator programme is also helping protect some of the country’s taonga species.

“We’ve found there’s quite a few rare and threatened species that are within our forests, including kiwi, the whio blue duck, the pekapeka bat, the kārearea falcon,” says Matt.

“So it’s really important, the work that we’re doing around pest control and predator control, to keep the numbers of those pests and predators down and enhancing the habitat for those species through the regeneration work that we’re doing.”

Ultimately the programme will see Aotearoa New Zealand enjoy a wide range of environmental benefits.

“The benefits are that we increase New Zealand’s biodiversity – we’ve lost an awful lot of it and all New Zealanders want to see our biodiversity increased,” says Richard. “We’re soaking up carbon, a critically important thing to do at this time. And we’re also creating some new native forests on land that should never have been cleared and has become an environmental problem because of erosion and the loss of biodiversity.”