26 May 2023, UK: Scientists from The James Hutton Institute are supporting an investigation into whether global warming is leading to increased carbon emissions from ecosystems in the Arctic.
The investigators from the James Hutton Institute in Aberdeen will join lead researcher Professor in Ecosystem Ecology Philip Wookey from the University of Stirling and colleagues from the University of Edinburgh to carry out cutting edge experiments in northern Sweden.
The group will also carry out its ground-breaking research in the Scottish Highlands, an environment that has much in common with the Arctic tundra.
An announcement of £1 m in funding for the project comes after the World Meteorological Organisation revealed there is now a 66% chance the planet will pass the 1.5C global warming threshold between now and 2027.
Rising temperatures are having a dramatic effect on the Arctic landscape – trees and tall shrubs are growing in areas formerly too cold for them to establish, meaning tree lines are gradually creeping up, and shrubby vegetation is spreading and growing taller, as warm seasons lengthen.
However, it is not yet clear if this Arctic greening is resulting in changes in net carbon exchange between ecosystems and the atmosphere. Plants do draw, or sequester, CO₂ from the atmosphere via photosynthesis, but at the same time, CO₂ is released from the soil and, in the Arctic, changes below ground may be disproportionately important.
With increased productivity and changes in vegetation composition, where plants are rooting in extremely carbon rich soils, there is concern that processes in the rooting zone (the rhizosphere) could result in a net loss of carbon, back to the atmosphere as CO₂.
The team, led by Professor Wookey, will carry out innovative experiments which will test whether vegetation change could turbo-charge the mycorrhizosphere – the microhabitat in soil where plant roots are surrounded by fungus – resulting in a net loss of carbon from soils to the atmosphere.
They will investigate how the presence of plant roots, and their associated mycorrhizal fungi, could accelerate the decomposition of pre-existing soil organic matter. Mycorrhizal fungi access nutrients from the soil for their plant hosts, however, some may increase soil carbon loss.
The team are setting up experiments at tree line areas of Arctic Sweden to work out which fungi are growing with pioneer trees and how much CO2 loss to the atmosphere they are causing. In the lab, the team will culture (or grow) these fungi and carry out more experiments to understand their role in soil decomposition.
By comparing these processes in contrasting vegetation communities, they can assess how ongoing and predicted changes in plant communities, from tundra heath to shrub and forest, would affect net ecosystem carbon exchange with the atmosphere.
Dr Thomas Parker, a co-investigator on the project from The James Hutton Institute, said: “There is growing evidence from the boreal forest that a small, but very important group of mycorrhizal fungi are centrally important for the carbon balance of forest soils. It is largely unknown as to what will happen when these fungi colonise the tundra. Filling in this gap could help better predict climate feedbacks.”
Professor Wookey said: “Many high-profile research papers have equated Arctic greening with increased net carbon sequestration from the atmosphere. Although logical and intuitive, this overlooks the potential fate of pre-existing soil organic carbon in these regions. This is a problem because soils at high latitudes are notably carbon rich.
“Although challenging to investigate, we cannot overlook below-ground processes if we are to understand net carbon budgets on timescales relevant to the Climate Emergency. Understanding the fundamental mechanisms controlling the accumulation, stability, and loss of soil organic matter is as essential for predicting the Earth’s future climate as understanding photosynthesis and plant productivity.
“We hypothesise that associated changes in the mycorrhizosphere could, paradoxically, result in net losses, rather than gains, of soil carbon. By applying ground-breaking techniques, we will transform our understanding of this process and the fundamental new knowledge gained will significantly improve regional and global modelling of climate change. This project is especially timely, given the major policy emphasis and public interest in tree planting for carbon sequestration.”
The study led by Professor Wookey is one of 44 environmental research projects awarded a share of £25 m invested by the government to tackle significant questions about our planet.
A grant of almost £800,000 was made by the Natural Environment Research Council (NERC), one of seven research councils which make up UK Research and Innovation (UKRI), which is the national funding agency investing in science and research in the UK.
“This investment supports researchers’ curiosity and imagination to enable discoveries that unlock new knowledge,” said Professor Sir Duncan Wingham, Executive Chair of NERC. “By supporting high risk, high reward environmental science, we are harnessing the full power of the UK’s research and innovation system to tackle large-scale, complex challenges.”
The study Turbo-charging the mycorrhizosphere – Could more productive ecosystems threaten soil carbon stocks in boreal and sub-arctic zones of transition?will run until October 2026.
Drs Tom Parker and Andy Taylor from The James Hutton Institute in Aberdeen will work Professor Wookey on the project with Dr Lorna Street (Co-Investigator, University of Edinburgh); Dr Mark Garnett (Project Partner, NEIF Radiocarbon Lab, University of Glasgow); Dr Karina Engelbrecht Clemmensen and Prof Björn Lindahl (Project Partners, Swedish University of Agricultural Sciences, SLU, Uppsala) and a Post-doctoral Research Associate (to be appointed).
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