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NZ could buy time by planting trees – lots of them

The transition to a low-carbon economy will require deep changes to transport, energy and farming – but forestry experts say large scale planting of carbon-gobbling trees could buy us precious time as we make the shift.

Photo/Getty Images
Photo/Getty Images

This article is an excerpt from our May 7, 2016 special report on how our lives will change as the world heats up and we move to limit greenhouse gas emissions.

When it comes to deep emission reductions, we don’t have a silver bullet – but we do have trees and ample land on which to grow them.

Travel through the hill country of the North Island or the degraded and scrappy flanks of the South Island high country and you start to see the potential that forestry expert Mark Belton sees: fragile, erosion-prone land that could become a large carbon sink.

By various estimates, New Zealand has 1.2-1.3 million hectares of steep, vulnerable land “begging for trees”, says Belton. Tree planting could offset our intractable agricultural greenhouse gas emissions, with forest stands integrated into the “weft and weave” of rural land use. Aside from the carbon they would absorb, he says, there could be big benefits for farm incomes and improved bird habitat, soil conservation and water quality.

He has a vision of mixed exotic permanent forests – much like the 100-year old woods around the North Canterbury tourist town of Hanmer Springs. Eucalypts and the ubiquitous Pinus radiata suck up CO₂ at the highest rate, but Californian redwood, larch, oaks and Douglas fir could also be added to the mix of carbon-soaking woodland.

Although many would prefer natives, Belton says they are much more expensive to establish than exotics such as pine and are generally too slow-growing to achieve the rapid uptake of CO₂ that’s needed. But he says exotic forests can create a nursery environment for a regenerating under-storey of natives.

Mark Belton: New Zealand has 1.2-1.3 million hectares of steep, vulnerable land “begging for trees”. Photo/Sam Brett
Mark Belton: New Zealand has 1.2-1.3 million hectares of steep, vulnerable land “begging for trees”. Photo/Sam Brett


New Zealand already has a scheme to encourage permanent tree planting – the Permanent Forest Sink Initiative (PFSI), set up in 2008 – under which land­owners are given carbon units for each tonne of carbon their trees remove from the atmosphere. Theoretically, the landowner can earn an income from the trees by selling the units under the emissions trading scheme (ETS) to companies that need to offset their emissions, such as oil and cement companies.

But the PFSI has languished as a result of the flood of cheap Ukrainian and Russian carbon units into the ETS after 2011, which destroyed the market for forestry units and removed any incentive for landowners to plant trees for carbon. According to a recent paper by researcher David Hall for the green business group Pure Advantage, less than 16,000ha has been planted under the PFSI.

“The only thing that’s missing is a proper carbon price, and certainty of price,” says Belton, who calculates that a price of at least $20 a tonne would be needed to give forestry investors an attractive rate of return on carbon forestry, given the high price of rural land. Currently it is around $13 and it has been as low as 10-15c.

Professor Euan Mason: just planting trees could be enough to achieve carbon neutrality. Photo/Martin Hunter
Professor Euan Mason: just planting trees could be enough to achieve carbon neutrality. Photo/Martin Hunter


Euan Mason, forestry professor at the University of Canterbury, has also modelled the potential for forestry to deliver deep carbon reductions. He says planting trees on 50,000ha a year of erosion-prone land for the next 26 years – less than the rate of commercial planting that occurred in the 1990s – could achieve carbon neutrality for New Zealand in some years (trees absorb different amounts of carbon through their growth cycle). If radiata pine was planted and left unharvested it would eventually revert to native forest, as long as local seed sources were available, he says.

Modelling shows that a programme of planting on this scale would need a carbon price under the ETS of $50 a tonne to create a sufficiently strong incentive for landowners, although a price of $20 could trigger planting at a rate of 20,000ha a year.

But as Hall points out, New Zealand is heading in the opposite direction to that suggested by Belton and Mason. “We are cutting down more trees than we are planting,” he says, with the rate of cutting exceeding the rate of planting by about 8500ha a year on average since 2008. “Growing forest simply isn’t seen as prosperous in the long run, neither as a substitute nor a supplement to agriculture.”



To achieve mass forest planting, finding the money needed is key, says Hall, who calls for a “smorgasbord of funding” options. One way to “build bridges between forests and finance” would be state-guaranteed environmental impact bonds to provide capital for native forest planting. Another “quick fix” to encourage permanent forest planting under the PFSI would be to create a premium Permanent Forest Unit under the ETS (in recognition of the fact the trees can’t be cut down), with emitters having to hand over a certain quota of such units when they settle their carbon accounts at the end of each year. This way, even if the price of ordinary carbon units remains low, the demand and price for permanent forestry carbon offsets would increase and remain stable.

Tree-planting alone can’t save us from global warming, Hall says, but it will be “an essential part of a combined response, reliably buying us time in our carbon budgets while we make the tricky technological and economic transition into a low-emissions economy”.

Read more: 

  Special climate report: Forest residue could be turned into a vast renewable energy source.
•  Special climate report: Reducing demand for animal protein is crucial, but challenging for a country like New Zealand.
 Environmental philosopher Dale Jamieson says to get action on climate change we must first understand human psychology.
 Rising seas will have profound effects on coastal towns and cities – and nowhere more so than Dunedin.
•  Transition to a Low-Carbon Economy for New Zealand”, Royal Society of New Zealand. 
 “New Zealand’s Low Emissions Future: Transformational Pathways to 2050”, Motu Economics. 
•  New Zealand Energy Scenarios: Navigating Energy Futures to 2050”, BusinessNZ Energy Council. 

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