Introduced animals are damaging the native forests of Aotearoa New Zealand.

The management of introduced animals helps to restore the ecological health of our native forests, creates jobs and supports businesses. Could animal management also help New Zealand to meet greenhouse gas emission targets?

The purpose of The New Zealand Native Carbon Initiative is to leverage the value of additional carbon generated by animal management in our native forests, for biodiversity, climate and economic benefits.

Two major challenges facing Aotearoa New Zealand are:

• The health of our native forests is declining, as introduced animals run wild. Possums and deer destroy young trees, and older trees die earlier as these animals eat their leaves. Rats and stoats disrupt forest growth and regeneration by eating seeds and birds, which disperse seeds. An estimated 25 million native birds in New Zealand are killed each year by rats, stoats, possums and other introduced predators, rapidly diminishing our biodiversity.

• Global climate change is happening. Aside from the environmental and social impacts, New Zealand will need to spend billions of dollars to meet its international commitments to reduce net emissions. The Treasury estimates the cost to purchase carbon credits from overseas to meet the 2030 commitment to be as much as $23.7 billion. Meeting the 2050 commitment will be even more challenging.

Could animal management in our native forests help address the climate change challenge?

Forests store carbon

Carbon dioxide is a greenhouse gas. Trees and other plants absorb carbon dioxide from the atmosphere as they grow. Carbon dioxide is converted into carbon and stored in the plant's branches, leaves, trunks, roots and in the soil. This process is a form of ‘carbon sequestration’.

Introduced animals might be impacting carbon storage

While it is generally recognised that native forest vegetation and overall biodiversity rebounds as a result of the management of introduced animals, there is currently limited evidence of a positive link between this type of activity and additional above-ground carbon stocks. 

Several studies have been conducted on carbon stocks in native forests and the impact of introduced animals. However, none of these studies have looked for the link under an intense management regime and for the very small increment in carbon stock change over a short period of time required to support the economic rationale underlying the Initiative.  

The New Zealand Natural Forest Inventory has identified a significant decline in total carbon in kāmahi-podocarp forest — 8.0±6.1 tonnes of total carbon per hectare — over the over the 7.7-year period between the first two measurement cycles (2002-2007 and 2009-2012) of the Inventory. 

Kāmahi-podocarp forest is widely distributed across the country; it covers approximately 2 million hectares, and makes up 29% of all native forest types. 

The cause of the carbon stock decline in kāmahi-podocarp forests is unknown, but we suspect that the decline is the result of browsing by animals like possums, deer and chamois. Nationally, since 2002, there also appears to have been a shift in forest composition as numbers of plant species that are palatable to possums and ungulates have declined, while unpalatable species have increased.

Consequently, the Native Carbon Initiative will initially focus its efforts on kāmahi-podocarp forests. We have started the research programme required to find out whether the small-scale changes in carbon can be quantified, and attributed to the results of the intensive management of introduced animals.  

Proof of a link could present significant economic benefits

Under the Paris Agreement, New Zealand can account for carbon stock changes in pre-1990 forest resulting from new management actions. In accounting terms, ‘additional carbon’ would be the difference between the carbon stored in a native forest with intensive management of introduced animals (specifically the elimination of possums, rats and stoats, and the suppression of ungulates) and one without. 

We’ve done some initial economic modelling to estimate the amount of ‘additional carbon’ that a new animal management project would need to generate for the project to be cost-effective. The results showed that, in order to achieve a suitable commercial return on the cost of animal management over a 25-year period:

• The forest would need to sequester an additional 0.25 tonne of carbon per hectare, per year.

• That equates to 25 grams of carbon per square metre per year; which is equivalent to approximately 50 grams of wood.

• 0.25 tonne per hectare per year increase in stocks equates to a 0.1% annual increase in the carbon stocks of kāmahi-podocarp forest.

Such a small increase would make a significant total contribution to national emissions targets if animal management is applied over large areas of native forest. 

Furthermore, based on Treasury forecasts, the carbon could be generated for about one-third of the cost of purchasing carbon credits from overseas.

So, the answer to the question in the heading above is: no one knows. But if the answer was proven to be ‘yes’, then the benefit for New Zealand’s native forests and tax payers would be immense.

What will this Initiative do?

The work plan for the New Zealand Native Carbon Initiative comprises three parts:

1. Undertake research to prove the hypothesis that animal management generates additional carbon in native forests.

2. Develop a mechanism that would incentivise investment in the research programme and in new animal management projects in native forests.

3. Subject to the development of an investment mechanism, secure investment in the research programme and in new animal management projects in native forests.

We propose that the steps above happen concurrently because the problems we face demand urgent action.

Progress so far

To date, philanthropic investors and the Crown-owned charitable company Predator Free 2050 Limited have provided seed funding to initiate proof-of-concept research.

The current research programme has been developed in collaboration with researchers from SCION and NIWA. It involves using standard vegetation plot surveys to measure carbon and animal densities in a managed forest compared to an unmanaged forest.

The programme uses novel measurement techniques that are sensitive to tiny changes over short time periods.

Some examples of these techniques:

• Dendrometers that measure tiny changes in the diameter of individual trees every ten minutes, and transmit the results. The data will enable us to report small changes in carbon stocks over short periods of time.

• Monitoring stations that precisely measure atmospheric carbon dioxide concentrations as air flows from the Tasman Sea across South Westland forests. Previous work by NIWA indicates that native forests ecosystems absorb significant quantities of carbon dioxide.

• We are investigating the use of tree coring to provide insight into historic tree growth rates with and without the presence of introduced animals. Core samples are extracted as a straw-size sample of wood that enable analysis of a tree’s growth rings (without cutting it down).

There is risk: results are not guaranteed.

• Research may reveal that there are no measurable increases in carbon storage.

• If measured, we may not be able to attribute the increases to animal management in native forests.

  
  

How might this be funded?

Governments are generally reluctant to invest in this type of cutting-edge research. Instead, we are working with Government officials to develop an investment mechanism that will enable other funding pathways.

This mechanism would:

• Incentivise investment in the research to prove the concept.

• Allow investors to initiate new animal management projects in forested landscapes.

  • These projects would be initiated in anticipation that the research will quantify and attribute additional carbon.

• Need to guarantee investors the ability to generate a financial return for additional carbon (i.e. ‘carbon credits’) generated by the new projects.

  
  

There is work to do to realise this opportunity.

We recognise that there are many questions that will need to be answered. However, the potential for such immense benefits makes this opportunity well worth pursuing.

We are grateful for the support for the Initiative from a group of forward-thinking early investors.