Doubts on forestry conversion
A carbon farming business has bought swathes of the country and planted it in pine trees, promising it would one day regenerate into native forest – but researchers who’ve studied the concept doubt it will work.
New Zealand Carbon Farming has quickly grown to be one of the country’s biggest landowners, owning or leasing more than 89,000 hectares.
NZCF finds farmland with remnants of native forest nearby to act as a seed stock, then plants pine, which grows quickly and supplies a stream of income from carbon credits. The company says it selects sites with enough rain and decent soil, and it will thin the pine and control pests, such as deer and possums, to enable indigenous forest to grow underneath and, eventually, take over.
But two forestry scientists who helped pioneer the pine-to-native forest concept in New Zealand question whether native regeneration will happen on the scale the business is attempting.
Adam Forbes is a former research adviser to NZCF and, before joining the company, did his PhD research on using pinus radiata to mimic the environment
of a sheltering native forest.
His research has been cited by NZCF – a recent article by company employees in the NZ Journal of Forestry relied on five studies of which Forbes was the lead author and another study led by Forbes’ PhD supervisor, Professor David Norton of Canterbury University, among other research.
Forbes resigned from the company in 2019. This week, he questioned whether the business had conducted enough trials to know that regeneration would work in the various climates in which it was operating.
Active management of issues such as feral animals and weeds were difficult to tackle at scale of 10,000ha or more, said Forbes.
‘‘If they don’t get it right, we’re going to end up with large areas of pine that will be hell-of-a-difficult to work with, and probably harbouring a lot of pests.
‘‘The pines will only live for up to 200 years, we think, so what are the future generations going to be left with . . . if they’re not successful in getting a native canopy away in some of these areas?’’
NZCF managing director Matt Walsh said the business respected the need for more research, but said there were dozens of studies already on forest regeneration. Further studies were being done as the planting was rolled out.
‘‘Before we launched the business, we took scientific advice on the strategies that would enable us to reconcile the inherently slowgrowing nature of indigenous trees with the urgent need for carbon removals,’’ said Walsh.
‘‘While many scientists will look for the perfect set of ‘proof’ before endorsing any solution to any problem, the reality is that the planet cannot wait for the perfect data set. We need to take action now and at scale.’’
Norton, the Canterbury forestry professor, is not convinced. He met NZCF executives recently, and said they showed him evidence that some plantations were in suitable locations, with suitable natural seed stocks available.
However, he remained sceptical that the business had adequate long-term management plans in place, or enough guaranteed longterm funding.
‘‘They could show me they had killed a lot of goats, but that was for establishing the pine trees. I couldn’t see that they are yet thinking about how [native forests] will establish over 50-100 years,’’ said Norton.
‘‘We know as pine trees get older, the carbon sequestration starts to taper off – particularly after about 50 years. The concern is that at some point a disease or whatever knocks those trees out badly and there’s a big gap in carbon income, and where is the money going to come from to fund the management?’’
Walsh said he and his business partner hadn’t been able to find an investment model for indigenous planting that could be privately funded – without major subsidies – while also providing massive carbon sequestration. ‘‘This is one of the key reasons why we have elected to go down the regeneration path,’’ he said.
NZCF was established in 2010 and estimates forests under its management have sucked in more than 20 million tonnes of carbon dioxide – the equivalent of almost a quarter of the whole country’s annual emissions.
‘‘The areas they showed me would go faster into native forest if they had just had the goats taken off them and been fenced, rather than planting pine, but that doesn’t give you the carbon credits,’’ said Norton.