Health checks on the carbon in New Zealand's native forests were halved despite warnings over the risks
The Government may spend billions buying overseas carbon credits over the next seven years. But monitoring of the health of our biggest homegrown carbon store was halved to save $500,000 a year. Nobody plans to restore it. Eloise Gibson reports. Roughly every five years, intrepid conservation workers repeat an unusual, but critical, task hand-counting animal poop. Ranging far from the tourist trails, these workers visit hundreds of small patches of forest, each one 20m across, spaced at 8 km intervals from Stewart Island to the Far North. The so-called pellet count is how the Department of Conservation (DOC) knows if tree-munching species (deer, goats and the like) are increasing on the approximately one third of the country that is covered in indigenous forest. (Spoiler: they are). READ MORE: * World's largest pohutukawa forest at risk as myrtle rust discovered * Killing rats or possums not enough to save native species amid boom in hoofed animals * Forest-munching pests colonised a third more conservation land in the past eight years But these stoic workers arent just there to count poo pellets. They also count native bird populations , and carbon. New Zealand forests hold an almost unimaginable amount of carbon. Together, the trunks, branches, leaf litter, roots and other parts hold about 1.8 billion tonnes. If all that carbon was turned into carbon dioxide and released to the atmosphere, it would equal around 80 years of emissions from the countrys vehicles, cows, sheep, coal and gas burners and other sources combined. Most of it is contained in old-growth native forests, mostly on conservation land. Letting these forests flip from a carbon store to a carbon source would be catastrophic, a researcher told DOC in documents released to Stuff under the Official Information Act (OIA). Official statements typically say that forests planted before 1990 are in climate equilibrium , meaning that there is a balance between smaller regenerating forests (which suck in new carbon) and tall mature forests (some of which are stable, and some of which are losing carbon Westlands Kamahi-podocarp forests , for example). But theres a lot going on behind that word equilibrium. Because the areas are so vast, and the quantities so massive, the total figures are highly uncertain, DOC says. A 2021 Ministry for the Environment analysis estimated woody vegetation on public conservation land was losing the equivalent of 926,000 tonnes of carbon dioxide a year (the equivalent of the pollution from one of our largest industrial factories), because mature forest was losing more carbon than regenerating forests were gaining. However, the uncertainty in the numbers was so high that it wasnt possible to know if the loss was real trend, a blip or natural variation, the ministry concluded. There are many things that could flip a forest to losing carbon: climate change (and its heightened storms, droughts and wildfires); an explosion of deer, whose tree-munching can shift ecosystems; an attack of Myrtle rust, or some as-yet-unknown pathogen. Forest collapse is more likely when threats work together such as deer or goats stopping a forest recovering naturally from a cyclone, for example, or successive dry summers coming on top of a root-attacking pathogen . Read together, the two complete cycles of poop- , bird- and vegetation- surveys (starting in 2002 and 2007) revealed how some of those threats were interacting on a national scale. They formed the basis of a huge amount of research into the state of the nations carbon stores . But those five-yearly forest carbon measurements are no more. Nobody exactly decided to halve them, explains DOC, but the department couldnt continue them at their former frequency after the 2002 and 2007 cycles. Because of funding cuts, the tree surveys slowed until the vegetation monitoring of those forest plots was happening on a ten-year cycle by default, says DOC. The animal counts kept going on their five-year cycle, but they were no longer coupled with the same quality of data on the health of our native trees. While the first two surveys yielded groundbreaking insights, documents released to Stuff show users had more trouble gauging solid trends from the third. Halving the re-measurements to a 10-year cycle has compromised our ability to relate pest changes to forest survival, researchers noted in one discussion. Elsewhere, analysts talked of a loss of precision around herbivore (deer, goats) impacts since 2014, because reporting is now only half the data. DOC says the decision to shrink the monitoring programmes funding was difficult. But it also confirmed there are no plans to restore the money. The cuts happened during Covid-19-related border closures a tough time for all agencies, but especially DOC, which gets some of its income from international tourists, for example when they pay to stay in national parks. In August 2020, under former Director-General Lou Sanson, DOC cut $500,000 from the annual monitoring budget and then never reinstated it. However, the programme had been under pressure for a long time, internal memos show. An internal review found the monitoring was operating at near peak efficiency, but cost pressures kept nibbling away. The first monitoring cycle (starting 2002) measured 1041 plots in five years. The second one (starting 2007) covered fewer than 1,000, mainly because of budget cuts. The third cycle started in 2014, and, by 2020, was only three-quarters through, having surveyed 679 plots. As of early 2023, it was still going. DOC seems to have found the frequency harder to justify after the Ministry for the Environment, which uses the forest carbon count for its national emissions tally, said only needed to get the data for its purposes every ten years. The funding cuts happened against strong advice from external scientists, who warned that without five-yearly monitoring, DOC could miss critical threats. In 2018, scientists at Manaaki Whenua-Landcare Research gave examples of risks that would be missed on a ten-year cycle: evidence that certain trees were declining, impacts of tropical cyclones on forests, signs that a pathogen like Myrtle rust was hammering species such as rata or kanuka. DOC staff weighed in too they pointed out the surveys were the only structured information available to answer certain questions, such as a recent one from a Minister about the threat from deer and goats to the nations carbon stores. Surveying fewer sites each year could introduce bias in the data, reduce quality and make the information less timely, they said. (DOC says this advice led to the programme reducing its outputs to align with the less frequent surveys). DOC staff also noted that the Parliamentary Commissioner for the Environment had described the whole monitoring programme as ground-breaking. They pointed out that the Climate Change Commission wants New Zealand to boost its forest carbon, something thats tricky to do without good monitoring. The seeming lack of priority for the forest checks has raised eyebrows in some environmental groups. Like many government agencies, DOC is under instructions to be carbon-neutral for its own operations by 2025 , and has been considering buying electric chainsaws and offsetting emissions from its helicopter flights. But its also been criticised for failing to talk more about the gigantic carbon stash it cares for for example in its new wild animal management framework, which comes with $30 million of funding for deer and goat control. That framework talks about biodiversity, balancing competing values and improving the quality of game animals (deer, for example) but not protecting forests from releasing their carbon. Asked about the monitoring cuts, Nicola Toki, a former Department of Conservation director, who is now chief executive of nature advocacy group Forest & Bird, says it seems odd for DOC to cut the programmes funding right when it was proving its worth. Like the Manaaki Whenua scientists who advised against it, Toki fears that monitoring trees over 10 years is too slow to enable DOC to react to threats. 10 years is long enough for a native ecosystem to collapse completely, she says. If we are relying on our forests to store carbon and to help turn around our biodiversity crisis, then we need to be confident we actually know what is going on in them, she says. We need to know what state they are in and whether the millions of dollars we are spending is making a difference... without the right monitoring in place we are stumbling around in the dark. This isnt the time for stumbling, she adds. Theres a climate crisis, a biodiversity crisis, and an explosion of deer: the poop count showed that, between surveys, ungulates (deer, goats and pigs) were up 48% on public conservation land, and were found on 82% of monitoring sites. In briefings, DOC told Ministers that impacts on biodiversity (from ungulates) are evident. In 2021, Forest & Bird launched a campaign to convince the Government to blitz feral mammals like possums, deer and goats to the lowest possible level. It estimated a concerted blitz could let forests suck an additional 8.4 million tonnes of carbon dioxide a year equivalent to 15% of New Zealands emissions. The lobbying won the attention of Ministers, internal briefings show. However, DOC responded by saying there wasnt enough evidence to quantify how much carbon would be saved by culling browsing pests like deer (it told Stuff this is still the case). It told Ministers expanding aerial drops of 1080 poison (to kill pests) as the lobby group wanted would cost $5 million a year, with the overall cost of the groups wishlist reaching hundreds of millions. One of the practical issues DOC raised was the need for better monitoring. One thing DOC and Forest & Bird agree on is that monitoring trees on an 8km grid however often you do it is not enough on its own. They agree New Zealand also needs more detailed studies, zooming in on specific areas where pest control, fencing or other work is happening, to track the impact more closely. Otherwise, national monitoring over a huge expanse can swallow the effect of individual projects, making it hard to prove they have worked. Helpfully, in 2022, the Government launched a multi-million dollar, cross-government effort to study how to measure and increase native forests' carbon. This effort includes a long list of projects. Fiordlands Secretary Island will serve as a testing ground for the impacts of deer control, with other sites to come. NIWA is looking at carbon fluxes in wider Fiordland, while mana whenua and various agencies are tracking the impacts of restoring the East Capes Raukumara forest, after decades of neglect. Jason Mackiewicz, DOCs Acting Director Monitoring and Evaluation, says there is also monitoring planned as part of a new wild animal management plan, tracking what happens to a forest when deer and goats are better controlled, for example. Researchers are testing remote sensing technology, which could enable forest monitoring to happen more cheaply than getting boots on the ground. And scientists will mine the information already gleaned from the now-halved forest plot surveys, looking for potential drivers of carbon loss. However, Mackiewicz says much of this new research is in the design and procurement phase. The forest plots supply the baseline information that tells decision-makers what is normal, as well as possibly picking up new threats. By knowing whats normal, the Government might be able to prove its conservation efforts were making a measurable difference something that would show up in the national tallies. That could turn out to save serious money. Under the global Paris Agreement, the Government has promised to pay for any planet-heating emissions over a certain cap a cost already estimated at between $3.3 billion and $23.7 billion over the next seven years. If the Government could prove that conservation work had allowed forests to store more carbon, that carbon would come off the tally, at a saving of anywhere between $38 and $243 a tonne . Ironically, some of the credits the Government buys from overseas (to make up for a lack of domestic climate action) might come from paying for tree-planting (or overseas renewable energy projects, or other schemes). Storing more carbon in mature forest would also mean less need for new planting in New Zealand specifically pine, which is currently (and controversially) the cheapest carbon-sucking option. The exact potential to boost the carbon in mature forests is debated, as well as how safe that carbon will be from fires, droughts and other risks. DOC told Ministers Forest & Birds estimates were too high, and some of its plans were not feasible. But DOC itself has cited a study showing it could theoretically increase carbon stored on public conservation land by almost 700 million tonnes nine years worth of New Zealands emissions through a mixture of planting, protecting regenerating forest, pest control and other things. Achieving this would take decades or longer, and might not be fully possible, but the department agreed it was worth looking into. Meanwhile, Adam Currie, a campaigner with the climate group 350 Aotearoa, likens letting wild animals eat the forests to letting rats munch through the bottom of a lifeboat. It's much easier to push them past a tipping point than to push them back, he says. Stuff asked Conservation Minister Willow-Jean Prime about the cuts to monitoring, and whether New Zealand knows enough about the state of carbon in its forests. She supplied a written statement, highlighting new funding for pest control and new areas of research. She also noted the Ministry for the Environment has operational responsibility for carbon monitoring (although the actual work is done by DOC). As for the latest carbon count there is a new tally, dated March 2023. Stuff was told it would need to request it under the Official Information Act, which was done on May 4. Watch this 20m-wide, 8 km-apart space for details.