Forest soils are good habitats for bacteria that absorb and release methane (CH4) as a source of carbon and energy. By quantifying how much methane is consumed by the bacteria, known as methanotrophs, at field sites, the project will reveal just how important planted forest soils are to New Zealand as part of broader efforts that seek to better understand the country’s total net emissions and ways to mitigate climate change.
Once complete, the research will provide valuable insights for policy makers examining greenhouse gas emissions as it can be used to paint a more accurate picture of the country’s total net carbon budget.
Due to agricultural activity, methane production in New Zealand is disproportionately high on a per capita basis – about six times the global average. Understanding the potential for other land uses, such as forestry, to mitigate these agricultural emissions is critical, says Scion senior scientist Dr Steve A. Wakelin.
“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.”
He says New Zealand’s economy is reliant on the livestock sector for jobs, food and income. Scion’s research aims to show how forestry can support the agricultural sector to tackle one of its biggest challenges.
The Ministry for Primary Industries is funding the research, with support from Lincoln University. It follows international studies proving that forest soils create optimal conditions for the methane-absorbing microbes. As methane in the air passes over and diffuses within forest soil, methanotrophs consume the methane.
“We find methanotrophs are abundant in our DNA-based surveys of planted forest soils,” Wakelin says. “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.”
Photo: Scientist and project lead Kathryn Walker is measuring how fast soil microbes are consuming methane by taking gas samples from field chambers installed in forests