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The response to climate change

The response to climate change

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The Billion Trees Project

Summary

“Our past climate inaction means New Zealand now needs a rather extreme number of trees in a very great hurry. The question is how are these going to be delivered? And at what sacrifice?” –  ‘The sea of pines that is going to be needed to balance the NZ carbon budget’, Stuff 2019

Balancing the carbon budget: becoming ‘net zero’

Taking too much carbon and other greenhouse gasses (together called eCO2) out of the ground and burning them to fuel our modern lifestyles, and converting vast areas of the planet from carbon-absorbing forests to carbon-emitting intensive agriculture, is changing the comfortable climate that supported us for 10,000 years. While we can’t undo many of the changes now underway, we can reduce the impacts and adapt to what’s coming, by:

  1. Reducing our carbon spending: rapidly transitioning from fossil fuels to renewable energy and moving from outdated intensive agriculture to restorative agriculture.
  2. Saving carbon by capturing and storing it back underground. Often called ‘drawdown‘ the single best way to do achieve this is to restore nature, which captures and stores carbon permanently.

“Restoring a third of the areas most degraded by humans and preserving remaining natural ecosystems would prevent 70% of projected extinctions of mammals, birds and amphibians. It would also sequester around 465 gigatonnes of CO2—almost half of the total atmospheric CO2 increase since the Industrial Revolution.” – Strassburg et al, 2020.

The ‘One Billion Trees’ (OBT) Project: what it really means

While the title is inspirational, the ‘billion trees’ number is misleading as it includes replacing existing commercial exotic forestry, 50% of which is due to be harvested and in need of replanting just to maintain existing commercial forestry levels. The other 50% is intended to be a mix of new plantation forestry and native trees. So one billion trees really means around 500,0000 trees. That’s still a lot of trees, right?

But not all trees do that same job when it comes to permanently locking away carbon.

The benefits of restoring native biodiversity and the critical life-supporting ecosystem services they provide is well understood. One of these services is to draw down carbon from the atmosphere. Eventually, most if this carbon permanently store it underground as leaf matter and dead trees accumulate and are converted to soil.

Fig. 1: (Image: Nature)
Fig. 1: (Image: Nature)

Plantations of exotic trees might absorb carbon quickly, but once they’re harvested, almost all the carbon stored in the trees goes back into the atmosphere. Indeed, claiming that plantation forestry is ‘forest restoration’ is actually putting the climate at risk (Fig. 1).

“…munched on by insects and exposed to microbial bugs in the soil, invading species released 2.5 times the carbon dioxide from the soil into the atmosphere, compared to natives. Lincoln University researcher Dr Lauren Waller​ said the exotic plants interact very differently with the animal and soil microbes around them. The difference in carbon release was thought to stem from the introduced plants’ ‘higher-quality and quantity’ leaves. ‘These were more palatable to insect herbivores, and sped up rates of decomposition by soil microorganisms such as bacteria and fungi,’ she said.” – Stuff, 2020

The One Billion Trees project is run by Uru Rākau, a business unit within the Ministry for Primary Industries. Their mandate is to work with the Department of Conservation (DOC), Crown Research Institute for forestry (SCION), regional and district councils, and organisations such as the QEII Trust to deliver optimal outcomes at regional and local levels. This means that landowners wanting to convert unproductive farmland to forestry, can apply for round $4000/ha for natives versus $1500/ ha for exotics, in order to maximise biodiversity goals and/or provide high-value ecosystem services. Funding via other grants for projects such as wetland restoration, advice on landscape scale plantings and pest control/eradication under the Predator Free 2050 goal, and rates and tax offsets for some voluntary activities (ie, not legally required of the landowner under existing environmental regulations) also is available.

But in reality, planting and maintaining natives is 10-20 times more expensive than planting exotic forestry. Natives must be eco-sourced and are in short supply, they have low survival rates due to introduced pest species so they must be fenced and a permanent pest management plan must be in place, and technical advice is under-resourced. Native forests can never be harvested and sold as a sustainable forestry crop, which means the land must be permanently retired from some other potentially productive use by future generations.

Because natives grow slowly, the trees don’t store carbon as quickly exotic plantation forests do, so they generate a much smaller revenue in the short term under the current Emissions Trading Scheme (ETS). In fact, just the stumps and roots of an already harvested radiata pine forest bring in more revenue than an intact native forest of the same age (Fig. 2).

“Natural regeneration is occurring on Banks Peninsula on a massive scale, but because it is not financially incentivised we increasingly see large areas destroyed by aerial spraying as landowners perceive native vegetation or its nurse canopy as an invasive weed affecting income rather than carbon sequestration with potential to earn income.

“We submit that this is utterly counterproductive to the goals of the Climate Change Response Act. At best carbon sequestered in these naturally regenerating areas is not being included on the national register, at worst it is being replaced with methane emitting pastoral farming. Although we are Banks Peninsula focussed, we are aware of the same issues around the country.” –  Submission to the Parliamentary Select Committee hearings for the Climate Change Response (Emissions Trading Scheme) Bill, February 2020

 
Fig. 2: Under the current Emissions Trading Scheme, the 10 year-old stumps and roots of a harvested forest of radiata pine in Canterbury and the West Coast ('C/W') is more than twice as valuable in terms of carbon trading, than an intact native forest of the same age (Source: New Zealand Ministry for Primary Industries).
Fig. 2: Under the current Emissions Trading Scheme, the 10 year-old stumps and roots of a harvested forest of radiata pine in Canterbury and the West Coast (‘C/W’) is more than twice as valuable in terms of carbon trading, than an intact native forest of the same age (Source: New Zealand Ministry for Primary Industries).

Exotic forestry: the real costs and risks

Financial

No detailed budget analysis has ever been undertaken as to the viability of the OBT. This is because there are complex fiscal, accounting, and design implications in terms of the location, scale, and purposes of tree planting, and the uncertain future of carbon prices under the Emissions Trading Scheme. The value of harvested forestry also is uncertain, given the Bonn Challenge to restore 350 million hectares globally by 2030 will likely result in a global oversupply of plantation forest products in coming decades.

The carbon cost

Wood products are often regarded as ‘carbon neutral’. In reality the true life-cycle carbon cost is ignored because it’s virtually impossible to calculate. These costs include the heavy machinery cost of harvesting, shipping costs—mostly to China—and converting wood into products, which are then transported around the globe. Equally, most of the carbon stored in those wood products, whether it’s paper or houses or furniture, eventually ends up burned or rotting in land fills, releasing the carbon back into the atmosphere instead of permanently locking it away. 

Climate change risks: wind, higher temperatures, drought

There are also serious and urgent questions about the financial viability of planting some exotic tree species that may not survive predicted changes to New Zealand’s climate over the coming decades (Figs. 3 & 4).

Fig. 3: September 10, 2013 strong nor-west winds in Canterbury downed large sections of plantation forests. In one area, fallen power lines started a fire. Most of the damaged trees were immature or so entangeled that the cost of harvesting them far exceeded their commercial value. Most were felled and sold for firewood, with stumps bulldozed and burned, releasing the carbon back into the atmosphere (Image: Whitelaw).
Fig. 3: September 10, 2013 strong nor-west winds in Canterbury downed large sections of plantation forests. In one area, fallen power lines started a fire. Most of the damaged trees were immature or so entangeled that the cost of harvesting them far exceeded their commercial value. Most were felled and sold for firewood, with stumps bulldozed and burned, releasing the carbon back into the atmosphere (Image: Whitelaw).

Climate change risks: floods and soil erosion

One key reason for planting trees is to reduce the impacts of floods and soil erosion. But as the climate changes, alpine-fed rivers are likely to flood more frequently. The preferred method of harvesting plantation blocks in New Zealand is to clear the entire block, leaving nothing but ‘slash’ behind, making the land highly vulnerable to floods and soils erosion (Fig. 4).

Fig. 4: Lyn Rombouts among the masses of tree waste or 'slash' that washed down onto her Motueka property after heavy rain in February 2018. In clear-fell forestry, a system favoured in New Zealand's commercial forests, entire forests are removed and restocked at the same time (Image: Braden Faster/Stuff).
Fig. 4: Lyn Rombouts among the masses of tree waste or ‘slash’ that washed down onto her Motueka property after heavy rain in February 2018. In clear-fell forestry, a system favoured in New Zealand’s commercial forests, entire forests are removed and restocked at the same time (Image: Braden Faster/Stuff).

Climate change risks: wildfires

There is an increasing risk of wildfires, particularly from pine and eucalypt forests that contain volatile flammable compounds. These compounds become more concentrated as the climate grows warmer and dryer, making the trees even more flammable. In the South Island, the rush is to plant exotic species (Fig. 5), while wilding pines that continue to spread at an alarming rate (see below) were directly implicated in the 2020 Mackenzie fire.

Pine forests leading to an increase in atmospheric methane?

Methane is a potent greenhouse gas, and the amount in the atmosphere is rising rapidly. The volatile compounds produced by pine forests (which give them their distinctive smell and make them highly flammable) remove chemicals that help break down atmospheric methane. In short, while pine forests may mop up carbon, they may lead to an increase in methane, a far more potent greenhouse gas.

Soils are often overlooked when it comes to storing carbon, but in fact soils the Earth’s soils contain about three times the amount of carbon in the atmosphere and four times the amount stored in all living plants and animals. The soils of pine forests that have replaced native hardwoods in Germany do not sequester nearly as much methane as native forests.

Fig. 5: The rush to plant exotic trees is particularly prevalent in the South Island (Image: Stuff).
Fig. 5: The rush to plant exotic trees is particularly prevalent in the South Island (Image: Stuff).

A race against time. Are we sacrificing biodiversity and our climate beyond 2050, to reach net zero (in accounting terms) before 2050?

As Charlie Mitchell points out in this interactive article, the question of planting natives versus exotics is a ‘rabbit vs hare’ problem. New Zealand is committed to achieving net zero emissions by 2050. That’s just 30 years from now, less than the lifetime of plantation of exotic radiata pines. University of Canterbury forestry lecturer Dr Euan Mason estimates that because natives are too slow growing, to meet this accounting commitment and limit the impacts of climate change, we need to plant 5 billion of these fast growing radiata pines (Fig. 6). And because the climate already is passing dangerous tipping points, we need to drawdown greenhouse gasses as fast as possible.

Modelling by the Parliamentary Commissioner for the Environment estimates that an extra 2.6million ha. of forestry will be needed by 2050 plus an additional 2.8million ha. by 2075 just to maintain NZ at net zero. 

Currently, around 45% (12.1 million ha.) of NZ’s land mass is agricultural. Over the past 2 decades the trend has been to remove trees and convert farms and native ecosystems into intensive, industrial scale dairy farms requiring investment irrigation, which has led to a (still ongoing) rapid decline in waterways and destruction of wetlands.

In places like Canterbury and Southland, planting exotics is vastly outnumbering native species (Fig. 5). At the same time right across New Zealand, native forests, grasslands, and wetlands continue to be ‘under attack’ with offenders facing little consequences.

Fig. 6: According to Professor Euan Mason, New Zealand needs to sequester 1.4b tonnes of carbon (the area under blue line) but the One Billion Trees project - including the 500 million trees already allocated to replace existing foresty - will supply just 20% of that (red line).
Fig. 6: According to Professor Euan Mason, New Zealand needs to sequester 1.4b tonnes of carbon (the area under blue line) but the One Billion Trees project – including the 500 million trees already allocated to replace existing foresty – will supply just 20% of that (red line).

“Since the 2012…over a hundred thousand hectares of true land-use change [has been] going on around wetlands, scrub being cleared, and dairy land-use intensification.” – Landcare Research, 2020 

“Even the most egregious offences – including a dam built on a wetland, clearance of a nationally endangered form of kānuka, and aerial poisoning of swathes of regenerating native bush – often prompted little more than a warning from authorities.”   – Charlie Mitchell, Stuff, Oct. 2020

Wilding pines: the wrong tree in the wrong place

“…lose $4.6 billion in productivity through reduced water available to farmers and hydro-electricity schemes over the next 50 years, and through more money needed for forest fire prevention—or save the economy $5.3b over 50 years, by getting on top of the wilding pine problem and freeing up more productive land.” – MPI report to 2019 NZ Budget

Under the ETS, owners of wilding conifer stands that meet the criteria of a post-1989 forest can register for carbon credits without any obligation to manage the spread of wildings.

New Zealand has an unenviable history of planting conifer forests in unsuitable and/or inaccessible terrain subject to excessive erosion (see Fig. 4). Many species of conifers have self-seeded on prime agricultural lands and displaced globally rare ecosystem including tussock grasslands that, combined with associated wetlands and peatlands, can sequester higher levels of eCO2 than these conifers. These trees also remove water from catchments already depleted by intensive agricultural practices, and they destroy the hydrology of rivers, leading to floods and erosion. Further, they’re exacerbating fire risks at a time when vastly more resources are needed to combat the growing number and intensity of forest fires each year. So while it’s true that mature wilding conifers do absorb CO2 , they currently cover more than 1.8 million ha of land, causing economic losses in the billions and displacing native species and entire ecosystems that provide(d) essential services that are needed in the face of a changing climate. In spite of $11 million every years spent to control them, they’re spreading at an estimated rate of 5% annually.

At that rate, not including the added impact of planting five times as many conifers needed to balance New Zealand’s carbon budget, 20% of NZ will be covered in wilding pines, while  the original forestry block owners that planted them are not liable for their costs .

The one small piece of good news is that unlike other conifers, radiata pine does not commonly ‘wild’. As Professor Euan Mason points out, radiata has a ‘…superpower, growing fast and hoovering carbon dioxide while it’s still young, leaving other trees in a cloud of wood-chip.’

When a few individual radiata pines are left following plantation harvesting, they attract birds that carry and in turn drop seeds of native species. New growth of native forests spread out  from around these solo mature radiata, and in places where  high winds have felled them, they often serve as protective nursery areas for native samplings to take hold. Strategically placed (‘the right tree in the right place for the right reasons’) radiata might help NZ meet its 2050 obligations and then act as a nursery for natives to drawdown CO2 beyond 2050.

‘The right tree in the right place for the right reason’

The IPCC recommendations to eat less meet and the 2025 government-imposed deadline for NZ agriculture to enter the ETS (albeit with a 95% discount) is placing pressure on the rural sector to reduce emissions. For desperate over-capitalised farmers, plantation forestry is often viewed as a lifeline. In spite of objections and concerns from multiple sectors, the agri-industry is promoting OBT as an opportunity for sheep, beef and dairy farmers to integrate forestry (native and exotic) into their business, provided they do their homework and get the correct advice. This includes:

  • An ecological assessment of the suitability of plantation species in any given area based on climate change modelling over the lifetime of the crop.
  • A business/financial model that includes the marketing value of environmental accreditation and ecosystem services.
  • A risk assessment that includes fire management and landscape scale hydrological changes known to negatively impact watersheds in areas predicted to experience higher temperatures and winds.

Explainers

What is ‘eCO2′  or ‘CO2-e’ sequestration

Some greenhouse gasses are many times more powerful than others when it comes to warming the atmosphere. This is called their global warming potential (GWP). Three of these gasses, carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) are the main concern. Of these, CO2 from burning fossil fuels (coal, oil etc) is the largest. For this reason, CO2 is used as a benchmark against which the GWP of all other gasses are measured. This benchmark is called the carbon dioxide equivalent or CDE. This is often written as CO2eq, CO2e, or eCO2.

Some greenhouse gasses stay in the atmosphere longer than others, so time is also included in the equation. Over 100 years, the GWP of methane (CH4) is 25 times that of CO2, so it’s written as 25CO2-e. The GWP of nitrous oxide (N2O) over the same time period is 298, written as 298CO2-e.

References and further reading

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