Due to agricultural activity, methane production in New Zealand is disproportionately high per capita — about six times the global average.
Scion senior scientist Dr Steve A. Wakelin said it was critical to understanding the potential for other land uses, such as forestry, to mitigate these agricultural emissions.
“We know that forests are great for storing carbon from carbon dioxide, but this research is helping us learn about forestry’s capability to offset methane emissions as well.
“We believe it is a first step in a future programme of work that will demonstrate how different land uses in New Zealand are all interconnected, and how to manage these holistically for win-win outcomes.”
Wakeline said New Zealand’s economy relied on the livestock sector for jobs, food and income.
Scion’s research aimed to show how forestry could support the agricultural sector to tackle one of its biggest challenges, he said.
“Scientists are working on breeding lower-methane-emitting livestock, using methane ‘vaccines’ and inhibitors, and investigating farming system change such as feed and additives.
“However, even combined, these are unlikely to nudge the needle enough to meet our emissions reduction targets. As Aotearoa works towards a low-carbon future, this issue is one for us to tackle together.”
The research is funded by the Ministry for Primary Industries with support from Lincoln University.
It follows international studies that show forest soils can create optimal conditions for these methane-absorbing microbes.
As methane in the air passes over and diffuses within forest soil, methanotrophs consume the methane.
Methanotrophs were abundant in Scion’s DNA-based surveys of planted forest soils, Wakelin said.
“Indeed, based on overseas systems, it turns out that planted forest soils are pretty good habitats for methanotrophs; we just haven’t looked at this in New Zealand before.”
Scion’s microbial ecology soil systems team is now collecting New Zealand’s first field-based measurements of methane flux — how fast the soil microbes are consuming methane.
Researchers have installed methane flux chambers at two sites near Christchurch: Orton Bradley Park and McLeans Island.
At both sites Scion already collects environmental DNA and measures environmental properties; this information will now be integrated with the methane flux data.
Chambers have also been installed in Kaingaroa Forest in the central North Island — New Zealand’s largest commercial pine plantation.
A sampling of these field chambers will reveal how much methane the forest soil microbiome consumes during an entire year.
“If rates of consumption are high, we need to know as this data will be important for our national carbon budget,” Wakelin said.
“Given the importance of methane as a greenhouse gas for agriculture, it could just be a case of forests to the rescue.”
Lincoln University’s Professor Tim Clough said the collaborative research with Scion would reveal important data.
“With Scion’s expertise in forestry aligned with Lincoln University’s facilities for trace-gas sampling and analysis provided through the New Zealand Greenhouse Gas Centre, we have a great partnership in place to assess the big opportunity of forest methane consumption.”
Methane is responsible for about 25 per cent of global warming.
What’s more, each molecule of methane has about 28-35 times greater warming potential than carbon dioxide (CO2).
This means concentrations of methane in the atmosphere have considerably more potential to alter climate change compared with the same volume of carbon dioxide.
