An interview with Vince Gauci, PhD
Dr. Vince Gauci is an ecosystem scientist and biogeochemist who leads a research group at the University of Birmingham in the School of Geography, Earth, and Environmental Sciences. He specializes in atmospheric interactions with carbon-rich ecosystems such as forests, wetlands, and peatlands. His work frequently covers methane and nitrous oxide cycles, which are both increasingly driving climate change.
This conversation between Dan Goodwin, Paul Reginato, and Vince on The Climate Biotech Podcast focuses on Vince’s exciting new findings, published July 23 in Nature, that implicate methanotroph-colonized woody surfaces as a major contributor to the terrestrial methane budget. We explore the potential of leveraging these findings for atmospheric methane removal, the challenges to getting there, and remaining open questions. For a preview, check out the Perspective Vince published July 25 in ERL on the role of trees in methane mitigation.
Listen to the full conversation on Spotify or Apple Podcasts, or read on for snippets from the episode (lightly edited for clarity).
How does methane uptake work in trees?
We found that upland trees on freely draining soils are taking up methane through their woody surfaces. This is a substantial sink that we estimate to be around 25 to 50 teragrams or million tons of uptake a year, which is approaching 10 percent of the global methane sink term.
Essentially, you have two processes in conflict. There’s a small amount of methane production in the rhizosphere, in the soil, and you have methane uptake higher up in the tree. As you go higher up the trunk, the influence of the soil diminishes as the methane leaves or gets consumed, and the higher you go, the influence becomes on the methanotrophs that are inhabiting the tree surface and taking up the methane.
What are methanotrophs?
Methanotrophs are microbes that consume methane. In this case, they’re living on the surfaces of tree bark. It’s remarkable because they’re able to consume methane at very low concentrations — around two parts per million in the atmosphere.
We actually set out to look for trees that were emitting methane. This discovery was a bit of an accident. We patched together studies from different PhD students and postdocs within my team, working all the way from Sweden down to Amazonia.
This finding highlights an additional climate service provided by trees. It could potentially be leveraged for atmospheric methane removal. For example, in reforestation efforts, even young forest stands that haven’t accumulated much carbon yet could be taking up significant amounts of methane due to their surface area.
What are some next steps in this work?
We need to do more measurements in far more locations and at greater heights within trees. We’re about to start a project in Ghana to investigate how hydrology affects this process. We’re also exploring ways to potentially enhance methane uptake, such as addressing nutrient limitations for existing methanotrophs or adding new methanotroph communities to trees.
This could be particularly relevant for commercial forestry plantations. While some tree species used for pulp and paper are essentially CO2 neutral over their growth cycle, we now know they could be harnessing methane uptake while they’re growing. This adds a new dimension to consider in forestry management.
It shifts attention in trees from the photosynthetic apparatus in the leaves to the vast “real estate” of vertical surfaces in forests. It’s opened up a whole new area of study — the large unknown world of tree bark. As I said, “it’s clear we’re barely scratching on the surface.”