Carbon neutrality requires permanent forests not production forests

In recent months I have been writing about land-use transformation that will be driven increasingly by carbon trading. If New Zealand is to approach net-zero carbon, then it can only be achieved by a combination of modified lifestyles plus new technologies that either don’t yet exist or are yet to be commercialised. Even with all of these things, it will still require lots of forest plantings to offset carbon emissions from elsewhere in the economy.

A key point underlying the recent articles I have written is that the implications for rural-landscape change have been under-estimated and poorly communicated. A key thrust of this current article is that it is only by permanent forests rather than multiple-rotations of production forests that the march of the pine trees across the landscape can be managed.

To put some broad numbers around the situation, New Zealand’s current annual emissions of greenhouse gases, as officially measured, are approximately 80 million tonnes of carbon dioxide equivalent (CO2e). One key challenge in controlling these total emissions is that New Zealand’s population has been increasing recently at between 1.5 percent and 2 percent per annum, driven largely by immigration. These population growth rates are remarkably high for a developed country.

New Zealand’s forestry offsets as officially measured are currently around 24  million tonnes per annum of CO2e. This comes from the 1.73 million hectares of production forest. Nearly all of these forests will be harvested over the next 30 years.

Once existing forests have been harvested, that land can never provide more credits. Indeed, these lands must be replanted in forest just to avoid carbon levies being charged. This is because the essence of carbon trading is that only new carbon storage is rewarded. Once forests are harvested, then new carbon sequestration from replanted forests is needed to balance out what was lost from harvesting.

This means that if all New Zealand does is replace harvested forests, with no new forests from farmland, then it will be reporting back to the UNFCCC that its carbon sequestration is rapidly declining towards zero, whereas sequestration needs to increase.

To say that a little differently, replanting the current forests will not stop New Zealand going into reverse-gear sequestration rates. New Zealand needs to both replant harvested forests and also plant lots of new forests on farmland if it is to maintain current levels of offsets. And then plantings need to increase still further if offsets are to increase as the Government intends.

To put some numbers around that, if New Zealand wants to just maintain the current annual offset rate of around 24 million tonnes of CO2e, and if it plans to do this with production forests, then as well as replanting existing forests, it will need to plant new pine forests, with these new plantings marching across current farmland at about 65,000 hectares each year. All of these new plantings have to come from farmland.

The reason the march across the landscape has to be so fast is because production forestry is a weak provider of carbon sequestration. Averaged out over multiple rotations, these production forests only store around 350 tonnes of carbon dioxide equivalent. Under the proposed averaging system, credits from all of this are earned over the first 17 years.

This creates a perverse situation of short-term investor behaviours to generate cash being driven by the long-term benefits, yet the long-term benefits are only modest because of the harvesting.

As one scenario, if New Zealand wants to work towards sequestering around 35 million tonnes per annum of CO2e by 2050, and with interim targets along the way, then that is an additional 10 million tonnes sequestration per annum from currently. To achieve that with radiata-pine production forests, then the march across the landscape with new plantings is no longer 65,000 hectares, but around 100,000 hectares per annum, at least until 2050, and in all likelihood continuing on from there.

To put that in perspective, the total area of sheep and beef farming area is around 8.8 million hectares. So, by the end of this century the pastoral countryside, apart from the dairy land which is still too expensive to go into trees, and some dry land in Central Otago, would be a solid mass of pine trees. The current $10.5 billion of meat and co-product exports would be gone.

The obvious alternative is to focus on the steep erodible land and plant permanent forests. For example, each hectare of permanent pine forest will sequester between 1000 and 1350 tonnes of CO2e over a fifty-year period. Carbon sequestration will also continue beyond 50 years, but the official ‘look-up’ tables stop at that point, so the tables need to be extended.

The reason for focusing on radiata pine for the permanent forests is that these are the trees that grow the fastest in New Zealand conditions. Native trees sequester CO2e at around one quarter of the rate of pine according to the official ‘look-up’ tables.

However, in the long term it is feasible for mature radiata pine be replaced by indigenous forests. This requires an initial seed source for natives to grow in the shady spaces as mature pine trees die and fall. In big forests beyond the reach of seed-spreading birds, nature will need some help from humans to get the process started. That will be the task for future generations, perhaps 100 years from now.

With permanent pine forests, it would take about 1.3 million hectares planted progressively over the next 30 years to be giving us around 35 million tonnes of CO2e offsets at that time, with those offsets continuing for many years thereafter. Co-incidentally, that area of around 1.3 million hectares aligns with estimates of low-productivity erodible sheep and beef land that would benefit from being forested.

Permanent forests set up with radiata pines are not the perfect solution. However, they are the only solution with potential to provide the carbon offsets that will be needed if New Zealand is to meet its Paris commitments without destroying pastoral farming.

The big risks with pine forests are fires and exotic pests. So far, New Zealand has been blessed that the pests of radiata pine have not reached New Zealand’s shores. An attack of pine beetle could destroy a production forest, but in the case of mature permanent forests this might also facilitate conversion to indigenous forests.

The risks of fire relate both to production and permanent forests, but with permanent forests the area of pines can be much less.

The problem right now is that Government policies are encouraging behaviours for setting up of production forests on the better classes of land. The balance is out of kilter with long-term needs to get the right trees in the right place.

The key emergent question is how can New Zealand put in place the incentives and institutional frameworks to plant around 45,000 hectares of permanent forests per annum on the steep erodible lands, such that conservation benefits and carbon sequestration go hand in hand.

I have some ideas as to how that could be done, but that is a big discussion for another day. What is clear is that current policies are not going to get the right trees in the right place.

About Keith Woodford

Keith Woodford is an independent consultant, based in New Zealand, who works internationally on agri-food systems and rural development projects. He holds honorary positions as Professor of Agri-Food Systems at Lincoln University, New Zealand, and as Senior Research Fellow at the Contemporary China Research Centre at Victoria University, Wellington.
This entry was posted in carbon farming, forestry, greenhouse gases, Meat Industry. Bookmark the permalink.

18 Responses to Carbon neutrality requires permanent forests not production forests

  1. Rod St Hill says:

    Keith, thank you for your erudite analysis. I agree that planting permanent forests is the most viable way of offsetting carbon dioxide emissions and that is probably so for many coutries including Australia (but probably not with radiata pine in most parts of the country). You are right to point out the significant opportunity costs in terms of exports. It is a pity that policy makers are not always as forthright about the costs of offsetting CO2e as they ought to be. One thing I do like about planting trees is that it is reversible if the predictions from climat change models turn out to be wrong or if the global climate trend changes.

  2. Basil Walker says:

    Should the first conversation be about CO2 and what is wrong with it . Nothing is wrong with CO2 in fact plants love CO2.
    The next conversation should be about catalytic converters in vehicle exhaust which is the reason CO2 has grown because previously before catalytic converters in our vehicles Carbon Monoxide was the exhaust gas but catalytic converters changed to CO2. Take out the catalytic converters and save our farmland.

  3. David says:

    The 350 tonnes average needs to be used carefully. It’s an example only and in reality the average will be between 500 to 700 for radiata. No one in the forest sector would claim trees will solve this problem it simply buys time to change behaviour. If you use averaging you are really into timber anyway. For profitable timber you want better land that has better growth, lower engineering and logging costs. Environmental rules mean we don’t want hard eroding land. Land we and others have bought are foremost for timber. We believe, rightly or wrongly – time will tell, that its a good investment. Higher value land has a lower rate of return but it also has much lower variation – returns don’t rocket away but they don’t fall away as well. In higher land value carbon plays a smaller role in return, in fact it becomes negligible the higher it goes. Many in the industry are now mulling that we are better to buy better land, have a lower return but the risks are far lower. For pure carbon you want cheap land but some I have talked to in this space, all kiwi firms by the way, who won’t touch really tough land as just getting this planted is deemed to risky from a H and S point!! The main owners of the class 6e land and above are farmers – it will be a challenge to convince them their land should be the only land planted. Its scientifically the best result for NZ soil erosion and offset but a hard sell. As a NZ company we are allowed to buy good land and plant forests. It’s our money and our risk. Going by the farms being offered to us many owners seem very happy to sell.

    • trlahh says:

      Regarding steep, low value areas for planting, could these tree planting drones do the job?

      • Dave says:

        They could be useful on hard areas. The main constraint to establishing trees is competition from pest – plant and animal. For natives this requires a large ongoing commitment to animal and weed control. I personally believe if you want carbon and native planting pine and then leaving it to revert is the best. There is a lot of work going into this and some who are planting permenant pines are already establishing native seed sources in these forests. People would be surprised to see the effort being put into this at establishment already. Just be aware radiata will keep growing for over 80 years plus its a phenomenal tree for its ability to tolerate a range of sites. We should be thankful for this tree which provides so much employment and income for 1000s on NZers

  4. jbj4549 says:

    Well said, Keith. We need this sort of intelligent discussion rather than politician’s inevitable short term ‘fixes’, that grab headlines.

  5. nigel64 says:

    Thank you Keith for covering this in depth.

    The 18% CO2 increase in my lifetime is troubling. All our food plants are adapted to ~280ppm and it seems nutritional levels are highest in plants at around 280ppm. As far as I can tell 500ppm is where it starts to affect human cognition – about 20 years away.

    I have an on-going talk with the PCE on carbon sequestration. One issue in discussion is ancient carbon being released by thoughtless tree planting, i.e. any deep-rooted trees in the wrong place, perturbing ancient carbon and gasifying it. Shahzad et al. explore it in some depth in the linked paper:

    Root penetration in deep soil layers stimulates mineralization of millennia-old organic carbon, Soil Biology and Biochemistry 2018. [IDK if wordpress link will work]. Citations of this paper go in troubling directions.

    I hoped 1B trees would help NZ shift to long rotations of hardwoods(as in Belgium and Germany) enabling multi-use forestry and not requiring treatment. It would also have got us away from radiata which seem to be methane pumps from all the isoprenes they produce.

    Current government direction removes agency and control from farmers, a disincentive – the idea that they can help recover C where they are is a motivation for many modern farmers. That carbon has many forms, some short, some very long and that all forms may be able to be created on-farm is news to central government.

    • Keith Woodford says:

      Nigel64, Yes, this paper is quickly picking up citations. it reinforces a perspective I have that we actually know very little about soil carbon.
      Do you have a citation re the 500 ppm affecting cognition?

      • nigel64 says:

        Hi Keith, I thought I had a single tight citation and it looks like 600ppm is the known cognitive threshold. There may be blood chemistry changes at ~450ppm but I do not understand what I’ve read on that so have not posted it.

        There is a recognised knowledge gap between now at ~410ppm and ~900ppm (Bierwith, 2019). 2000ppm+ is common in most types of vehicles (ibid) and many buildings are in the very high 100’s to 2000+ (Allen, 2016). It seems as those are the main environments seen as hazardous to humans most study has been directed at those levels.

        Park, Loftness and Aziz, 2016 “occupant satisfaction with overall air quality is strongly linked to CO2 levels, with significant shifts to satisfaction when CO2 level is less than 600 ppm”. Using comfort as a proxy and then simultaneously testing the spaces.

        Satish, 2012. Observed a cognitive performance drop of 13% from 600ppm to 1000ppm.

        Allen et al. 2016. Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments. Environmental Health Perspectives, volume 124, number 6. Confusing public health study as it looks at eCO2 and VOCs simultaneously.

        Bierwith, 2019. Carbon dioxide toxicity and climate change: a major unapprehended risk for human health. Faculty – Australian National University.

        Jihyun Park, Vivian Loftness, Azizan t, Are Humans Good Sensors? Using Occupants as Sensors for Indoor Environmental Quality Assessment and for Developing Thresholds that Matter.
        Carnegie Mellon University, School of Architecture
        2016 ACEEE Summer Study on Energy Efficiency in Buildings

        Click to access 3bba6ab5813b2f971ff7d16681f89fd38dda.pdf

        Satish U, MendellMJ, Shekhar K, et al. 2012. Is CO2 an indoor pollutant? Direct effects of low-to-moderate CO2 concentrations on human decision-making performance. Environ Health Perspect 2012; 120: 1671–1677.

  6. Pingback: Rural round-up | Homepaddock

  7. Tom Walker says:

    Every time this topic comes up it makes me think of this well known quote by H.L Mencken..

    “The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary.“

  8. Declan Morrissey says:

    Hi Keith, interesting and thought provoking piece that feeds into the current climate debate at global level. A functioning international carbon market and full life cycle analysis of carbon emission and sequestration sources would facilitate such policies outlined above. Do you have any view on what price carbon credits need to be to make permanent forests financially viable? Also, I assume the rate of carbon sequestration of such forests is not linear and is highly correlated to the growth rate of the trees? I.e. a bit like the s-curve used to describe pasture growth?!!

    • Keith Woodford says:

      First of all apologies, I did not see this in the modration box (which is where first time commeters get sent). My current thinking is that $25 will be sufficient on steep country. But at this stage the investor institutions are not fully aligned to permananent pine forests. The dual income of carbon credits plus harvest potential is seen as having the least risk. But that coude change. Once the trees get to around four years of age then the growth is approximately linear for many years and the sequestration will be directly proportional to growth.

  9. There is a method to continuously and indefinitely remove carbon from the oceans and the atmosphere. This involves growing large scale plantations of bamboo into poles. The bamboo poles once harvested would be used as buoys to support and grow free-floating kelp forests in the South Pacific, Southern ocean and in the arctic circle. This system ( The Peel technique) could run indefinitely locking away gigatons of carbon annually. Please visit,

  10. I forgot to mention the on going employment for much of New Zealand. This would keep Northland and other districts fully employed for hundreds of years.

  11. John Chapman says:

    Wonder if you have seen this article Regards John C

    Sent from my iPhone


  12. Pingback: Economic opportunities for biochar in New Zealand | Peter Winsley

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