Last month I called for a bloody big new forest in New Zealand: 1.3 million hectares by my reckon. Could be more, could be lessĀ āĀ but this is the right ballpark for a meaningful reduction to our net greenhouse gas emissions.
The report, Our Forest Future, prompted plenty of discussion, but one issue stood out: a lot of New Zealanders have had a gutsful of Pinus radiata.
Iāll save the pros and cons of radiata for another day. Here Iāll discuss some alternatives; specifically, the potential for native trees as commercial forests. Because by bringing new native forest into the mix āĀ for commercial planting as well as conservation planting āĀ we can plan for a forest future that New Zealanders might actually want.
Common opinion will tell you that natives grow too slowly to be profitable. But the reality is more complicated.
āItās like a craft beer versus a Tui beer,ā says forester Clayton Wallwork. ā[Native forest] is more expensive to establish, but youāre going to get a higher-quality timber, a higher-quality product, as a result. Youāre also going to have a whole lot of other benefits āĀ to the community, to the environment.ā
Wallwork is involved in a project called āOur Forests, Our Futureā, led by Taneās Tree Trust. The intention is to get a better handle on the economic potential of native forest, not only for timber but also for environmental benefits.
The project is ongoing, focused on demonstration forests of beech in the South Island and totara in Northland. Trials wonāt be complete until 2018 āĀ but early signs are positive. Theyāre looking at the processing, the timber grading, the pricing; and Wallwork says of the totara that āitās already a lot higher than what youād get for radiata.ā
You might wonder: how can anyone do field trials on trees when they take so long to grow? Wonāt it take decades to get results?
The Northland Totara Working Group, established in 2005, looks at totara that self-regenerated on farmland. As long as landowners left the seedlings to grow to maturity, these decades-old trees can serve as approximations for how totara would grow if planted deliberately. Since 2007, the Working Group has pruned and thinned these forest plots, to see how they respond to best forestry practice.
Dr David Bergin, who also works on the project, is an expert on totara, a wood prized for its durability and workability. Heād like to see a more nuanced national forestry, where weāre āmatching the appropriate species to the appropriate site⦠blending in a diverse multi-use forestry with existing land uses.ā
Our commercial forests are currently 90 per cent Pinus radiata. Bergin says: āWith radiata, youāre dealing with a high volume, low value, commodity; so, youāve got to grow that on an industrial scale.ā Heās worked alongside MÄori landowners in Northland managing large pine plantations, mostly shipped to China as cheap unprocessed logs. He says ātheyāre getting a peppercorn rental; theyāre on steep difficult country with poor soils; theyāre hardly making anything out of it after trucking costs āĀ so itās marginal even for radiata.ā He says thereās a real hunger for alternatives.
Forestry research centre Scion is also engaged in indigenous forest research. One recent study found that kauri, along with mÄnuka, made positive economic returns in six areas around Northland (see graph below). Indeed, in four of the six areas, the investment case for kauri was superior to, or comparable to, Pinus radiata, both pruned and structural-grade.
The study estimated the land expectation values (LEVs) for different kinds of forest, then calculated incomes by factoring in costs of planting, harvesting, transport, and annuity. The areas where radiata performed bestāSouth Hokianga, Central Taitokerau, and South Kaiparaāwere all areas where markets were closest and transport costs low. But, averaging across them, the income for kauri was estimated to be 4.7 times higher than structural-grade radiata pine over a 60-year period.
Land expectation values (8% discount rate) of Pinus radiata (prune and structural grade) alongside native species. Source: Scion, 2014.
So, if native trees arenāt such a bad investment, why arenāt we growing them?
For decades, native forestry has been held back because reliable information is all-too-rare and unreliable information is all-too-common.
One of the researchers on the Scion study, Greg Steward, tells me: āItās about getting us away from that anecdotal information thatās been promulgated around the countryside since the days of Kirk and Cheeseman.ā
When Steward studied kauri for his Masters degree at University of Canterbury, he found far higher rates of productivity than anyone expected, occasionally getting close to Pinus radiata on optimal sites. Since then heās helped to develop the Kauri Calculator, an online tool for landowners which predicts future production and income for kauri.
People are taking a second look at natives, he says, ābecause now weāve got data. You can deny anecdotes until the cows come home, but you canāt deny data.ā
Misinformation goes back as far as early European settlement. Under the Waste Lands Act of 1854, native forests were defined as precisely that āĀ as āwaste landsā āĀ and treated accordingly. The common view was that one blade of grass was worth more than two trees.
Not everyone went along with this. By the late 1800s, says Steward, āvarious folk were starting to question how we were managing our forests and our native timber resources.ā At the time, we were not only cutting down ancient forests to export timber overseas, we were also starting to import foreign timber to meet local demand. Yet New Zealand chose to undertake large-scale planting of exotic pine throughout the 1920s to boost domestic supply. In 1919, forester Sir David Hutchins observed: āfor reasons which have never been satisfactorily explained, it has been thought to replace the valuable native forest of New Zealand by artificial plantations of exotics ā a quite unusual proceeding in forestryā.
Some early field trials for natives āĀ although showing promise āĀ were sidelined in this rush to plant exotics. Later trials were conducted on public land, often at high altitude or on land recently clear-felled. Unsurprisingly, these sub-optimal sites produced sub-optimal results. Some historical data, Steward says, no one knows its origins, nor therefore its reliability.
A 17-year-old kauri stand near Tauranga with stems of 34 centimetres diameter at breast height. Recent density analysis of this stand indicates growth rate is not affecting wood density. Source: Steward et al., 2014. Republished with permission of Greg Steward.
Meanwhile, Pinus radiata has benefited from decades of government and industry research. Landowners can easily estimate their return-on-investment for radiata, as well as carbon sequestration rates. Selective breeding has also made it a āsuper-speciesā, fast growing and resilient to disease. While thereās no reason that native trees couldnāt also be optimised through selective breeding, that work hasnāt yet been done.
To put it bluntly, New Zealand forestry is suffering from a bad case of āpath dependencyā. In other words, our decisions in the present are constrained by decisions from the past. The historical dominance of Pinus radiata makes its continued dominance a foregone conclusion.
Itās this hurdle that Wallwork, Bergin and others hope to overcome with the āOur Forest, Our Futureā project.
āThereās knowledge out there,ā says Wallwork, ābut no one can see a demonstration forest thatās been done, that has the books open to show what the potential revenues are.ā
Bergin adds: āThis project is about getting blocks of reasonable scale, demonstrating best practice, and dispelling those misperceptions out there.ā
Itās not that Bergin is dead-set against radiata: āIt seems to occupy a gap in our flora that we donāt have an equivalent to. Itās very plastic, grows on a range of sites, itās very forgiving, it grows really fast initially.ā
But he wants to see āmulti-species, multi-age, multi-purpose forestry as a mosaic across a landscape, for which I think native forestry has excellent potential to blend in with those other land uses.ā He reckons that once we go down this route, āthis is where the real foresters come out of the woodwork ā if you know what I mean ā where they have to understand forest ecology, not as a crop but as an ecosystem.ā
But that transition will require effort. To break the path-dependency of Pinus radiata, there needs to be more research, which means more research funding. Itāll also require market development, particularly educating New Zealanders to choose sustainably grown native timbers, rather than import foreign timbers which arenāt always sustainably harvested. Itāll require industrial-scale nurseries and economies of scale to bring down the price of establishment. Finally, where local rules prohibit the felling of all native trees, even those that were planted deliberately, weāll need to find regulatory solutions that enable sustainable native forestry without endangering conservation efforts.
So what about climate change?
Evidence shows that natives, on average, donāt grow as quickly as Pinus radiata, and so sequester carbon more slowly.
Granted, thereās room to improve the growth rates of natives through selective breeding. Thereās also room to be smarter about which trees go where: the right native tree on the right site with the right aftercare will likely defy many peopleās expectations. Wallwork tells me that mÄnuka on the East Coast can compete with radiata in terms of sequestration. But this will likely only narrow the gap between the early growth rates of natives and exotics like radiata and eucalyptus, not close the gap entirely.
Predicted carbon sequestration rates on average sites. Source: TÄneās Tree Trust, 2014.
Yet there are other things to consider.
A lot of what forests sequester isnāt in the wood, but in the biomass below the ground or on the forest floor. Kauri forest has one of the highest biomass carbon densities in the world. Although this below-ground biomass is excluded from conventional carbon accounting, from a climate perspective, itās still carbon thatās locked out of the atmosphere.
Another issue is resilience. For example, kauri, once established, is highly resistant to drought, indeed even has a competitive advantage inĀ dry conditions (thatās why kauri often clusters on ridgelines). It is also, like totara, a sturdy tree that isnāt susceptible to wind throw. So, if global warming means more droughts and more violent storms for New Zealand āĀ which is what the Royal Society predicts āĀ then thereās good reason to plan more diverse forests, rather than gamble on a monoculture thatās uniformly vulnerable to the same hazards.
Thereās also questions over long-term strategy for permanent forests. Bergin notes that, although some exotics have a growth advantage in early decades, this diminishes over successive decades because the growth of radiata eventually plateaus at around fifty years. Once weāve reached, say, one-hundred years, though, weāre talking about mature native and exotic forests that are storing comparable volumes of carbon. But the native forests may well be more sustainable over the long run, because of their intrinsic value and more diverse income opportunities. Wallwork notes that, when carbon forestry was first floated, all sorts of ridiculous plans were hatched for densely spaced forests of radiata, unthinned and unpruned, which would have aged into hazardous and unmanageable forests with little value beyond their stored carbon. Such forests, as you can imagine, would be first in line for land use conversion.
What are we to learn from this?
Our forest future doesnāt need to be a future of Pinus radiata alone. There are alternatives on the table. And thatās just as well, because as long as landowners have a choice over what they plant, then many landowners wonāt want to plant radiata pine (at least not without handsome incentives). Given that the majority of land available for future forest is privately owned, climate policy needs to take seriously the preferences of people, whether its their aesthetic preferences, cultural values like kaitiakitanga, or concerns over biodiversity and wilding pines. A native tree in the ground will always sequester more carbon than a fast-growing exotic that never gets planted at all. This is why, in the Our Forest Future report, I called for a principle of āappropriate diversificationā.
Fortunately, native trees are not only a feasible option, theyāre sometimes the more profitable option, especially when landowners pick the right tree for the right site. That doesnāt mean we should only plant native trees with commercial purposes in mind. Native tree planting for conservation projects, for habitat restoration, for permanent forest sinks, and for riparian planting should be a part of the picture too āĀ the bigger the better. But anyone who relies on their land as their principal source of income needs to make ends meet. Native planted forests āĀ sensibly managed ā can strike a balance between favourable economic returns and favourable environmental outcomes.
And if that isnāt green growth, then I donāt know what is.
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