Trees are Green - How DOC-managed land can help with New Zealand's carbon debt
D'Urville Island
Why does planting trees help?
Sustainable conservation
DOC-funded science is showing that growing trees and eradicating pests on conservation land - worthwhile for its own sake - can also help offset New Zealand's carbon emissions.
Moawhitu, on the remote western side of D'Urville Island, is an area of steeply rolling hills, much of it cleared but some covered in lush stands of indigenous bush, including kohekohe (New Zealand mahogany) and several species of beech.
To the west, the former farm plunges sheer into the Tasman Sea. To the south, it slowly unfolds towards an area of dunes, a large freshwater lagoon and a beach. The dunes are pitted with archaeological sites - testament to hundreds of years of Maori occupation. The site is rich in history, and also in natural beauty. 'It's a pretty neat area,' says DOC's community relations project manager for the Marlborough Sounds Robin Cox. Two years ago, the Nature Heritage Fund (set up by the Government in 1990 to buy private land with high conservation values) purchased the land and added it to the D'Urville Island Scenic Reserve. A coastal camping site opened in 2007, and, this year, Moawhitu became one small part of New Zealand's response to climate change.
In late July and early August, while storms whipped the northern South Island, 20,000 trees - raised in Marlborough from seeds gathered on D'Urville - were barged to the island across French Pass, carried 20 or so kilometres by truck, and planted at Moawhitu.
Over the next four years, thousands more trees will make the same journey.
Not only will they help restore indigenous D'Urville Island forest to the site. As they grow, they will also absorb and store carbon, offsetting greenhouse gas emissions and reducing a small proportion of New Zealand's liabilities under the Kyoto Protocol.
Though Moawhitu is DOC land, the plantings are funded by the Ministry for the Environment.
DOC's Harry Maher
'This is part of New Zealand's Carbon Neutral Public Service nitiative,' explains Harry Maher, who heads DOC's carbon offset projects.
Under the initiative, six lead government departments - including DOC and the Ministry - are required to be carbon neutral by 2012.
While the first step towards neutrality is reducing emissions from energy and fuel use, offsetting unavoidable emissions is also part of the programme. 'The trees on D'Urville are part of the Ministry's offset portfolio,' says Harry.
Moawhitu is one of two sites DOC has provided for the offset programme. The other is on north-facing foothills near Mt Oxford in North Canterbury where, over time, grassland will become scrubcovered; then manuka and kanuka will become dominant, and eventually beech forest will return.
Offsetting a $480m liability
While DOC has been opening up land to help offset public sector greenhouse gas emissions, it has also been carrying out research on the potential benefits of improving the health of New Zealand's forests.
The latest government estimate is that New Zealand will have to purchase $NZ480 million worth of Kyotocompliant emissions units to meet its Kyoto Protocol obligations.
What would happen if some of that money was spent on conservation work such as planting new bush, supporting regeneration, and controlling pests such as goats and deer which eat native vegetation?
The potential, the research suggests, is significant. The total carbon stock on the 8 million hectares of land managed by DOC has been estimated at around 2400 million tonnes (Mt) of carbon, equivalent to about 8800 Mt CO2e.
Two-thirds of that carbon is locked up in indigenous forests. Beech forest is the biggest single category with a carbon stock of 2300 Mt CO2e, just over a quarter of the total. Work by Landcare Research suggests that, with careful management, the stock could rise to about 9500 Mt CO2e - roughly an 8 percent increase - over 300 years.
Most of this increase would occur as existing forests grow and mature, but a significant amount - about 270 Mt CO2e - would be the result of forest and bush regenerating on land that was not forested at the end of 1989. Under Kyoto rules, all of the carbon in forests established after that date can qualify as internationally tradable carbon credits.
New Zealand's total emissions in 2006, by contrast, amounted to 77.9 Mt CO2e.
The size of the carbon sink protected on public conservation land - all 8800 Mt CO2e of it - highlights the importance of management to prevent deterioration and loss of trees, shrubs and soil that are the repositories of this carbon stock. Landcare's research suggests that the best ways to enhance carbon stocks on conservation land are to minimise losses caused by forest fires or other major damage, and to establish new forests on grasslands.
Managing existing forests to increase carbon brings long-term gains, but helping new forests to grow is much better in the short term. If this happens on land that was not forested in 1989 - and Landcare Research estimated that DOC has around 400,000ha - then the carbon removed can be used in national and international carbon trading.
'The numbers show there's a strong potential role for public conservation land in carbon sequestration.' - Harry Maher, DOC.
The picture for pest control is not so clear cut. New funding enabled DOC to establish the Wild Animal Control for Emissions Management (WACEM) Programme to investigate the potential for enhancing forest carbon sinks by controlling herbivores.
Greville Harbour, D'Urville Island
Unfortunately there's not much data available, nationally or internationally, on what impact pest control has on carbon stocks. Much more work is going to be needed before reducing the populations of possums or goats can be shown to have direct effects on carbon stocks - and that those gains are consistent enough to count towards carbon credits.
What we know suggests the gains will be relatively small and slow compared with establishing new forest. However, there are three areas where increases in carbon stocks could be important.
In broadleaved hardwood beech forests the carbon gains from herbivore control may not be very big on a per hectare basis, but the large size of the forest means that even modest gains will translate into a large amount of carbon sequestered.
In alpine and sub-alpine tussock grasslands, better herbivore control will increase the carbon stock, and in regenerating scrub and forest, pest control will protect young plants from damage and speed up the whole process.
Further research is also needed to determine the amount of carbon stored within the soil of our native forests.
Some carbon absorbed by plants and trees is sent down into the roots, where it feeds fungi and other soil life, and ultimately ends up in the soil itself. But it is not known exactly how much carbon is stored in this way.
Commercial sector investment
Alongside its research and its contribution to the Carbon Neutral Public Service initiative, DOC has also identified six areas for private or stateowned enterprise investment in carbon sink pilot projects.
Three of these areas involve native forest planting and restoration, and three involve getting rid of goats, deer and other pests to allow native forest to regenerate.
Key sites for bush regeneration are in Canterbury, Nelson/Marlborough, West Coast, and coastal areas of New Zealand.
These projects will involve businesses and state-owned enterprises funding bush regeneration on DOC-managed land. Over time, grassland or other habitat will be planted and - eventually - restored to indigenous bush. Businesses that take part in these programmes will be able to claim carbon credits.
DOC's decision to enable private investment in carbon sinks followed approaches from large corporates keen to gain carbon offsets by supporting initiatives on conservation land.
DOC is now working with Solid Energy on a project on the North Mokihinui block on the West Coast which will use pest control and forest regeneration to deliver carbon offsets. In addition, the project is designed to improve biodiversity in key areas.
If DOC land is to play a significant role in offsetting New Zealand's carbon emissions, partnerships such as these will be crucial - and it's also clear that they will have to go hand in hand with research to build a better understanding of the ways in which carbon moves through our native ecosystems. There's still work to do in determining the best sites to use to generate credits.
But, these qualifications aside, Harry, who also looks after DOC's commercial carbon projects, is bullish about the prospects.
'The numbers show there's a strong potential role for public conservation land in carbon sequestration,' he says.
'It's a big learning process we're going through, but as carbon trading becomes more important, we believe that indigenous forests on public conservation land will sequester significant quantities of carbon - and deliver other desired environmental outcomes.'
Plants take carbon dioxide out of the atmosphere and convert it to sugars, which are used to make the plant's body or sent down to the roots where they feed fungi and other soil life. In this way, the carbon is said to be stored or 'sequestered' from the atmosphere.
A hectare of mature beech forest can contain as much as 340 tonnes of carbon (excluding soil carbon) - which is the amount of carbon emitted by driving a large car six million kilometres.
When carbon is removed from the atmosphere in this way, it can be used to offset greenhouse gas emissions under the Kyoto scheme.
But the trees must be looked after forever for the benefits to be lasting.
DOC is one of six core agencies leading the way to carbon neutrality by 2012 as part of the Carbon Neutral Public Service initiative.
Kathryn Maxwell, DOC's sustainability manager, with help from many others, has been busy figuring out DOC's carbon footprint. She found a total carbon footprint (CO2e) of 9561 tonnes for 2006/2007, down from our 2005/2006 emissions of 10,309 tonnes.
DOC's aim is to achieve a 15 percent reduction in emissions within five years. Kathryn says this is definitely achievable. 'We're gradually replacing inefficient items with ones that are costeffective and sustainable, that allow DOC to continue core conservation work. One example of this is webcams, which save on air travel.'
To meet the 2012 timetable, DOC's priority actions to reduce its footprint are to accelerate the replacement of the vehicle fleet, reducing CO2e emissions from vehicles, to reduce air travel, by using webcams and targeted travel plans, and to reduce overall energy consumption through a range of energy conservation measures.
Conservation House
A star performer at reducing energy is DOC's Wellington head office, Conservation House, Whare Kaupapa Atawhai. In August, the New Zealand Association of Consulting Engineers awarded the building and DOC's building services team a Silver Medal for excellence in engineering innovation that went into the recent refurbishment of the building.
DOC was one of the first organisations in the world to put together lighting conservation as it has been used in Conservation House.
DOC's business services manager, Dave Alcock, says 'It was a bold and innovative approach, and technically a real stretch. But the rewards are there for all to see - currently we are burning power at about 2.25kwh per square metre. By international standards 9kwh is considered to be sustainable. We have set the bar - already there are 65 buildings in New Zealand that have either implemented the technology as we designed it, or are in the process of implementing it.'
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