Arctic plant roots play key role in climate change

The review, recently published in Nature Reviews Earth & Environment, highlights how processes occurring beneath the soil surface could help scientists better understand how one of the fastest-changing ecosystems on Earth will influence the future climate.

Arctic permafrost contains around 1,460 to 1,600 billion tonnes of organic carbon – roughly twice the amount currently found in the atmosphere. However, as climate change thaws this permafrost, some of this carbon is being released into the atmosphere. 

Thawing permafrost is also straining tundra ecosystems – the treeless area surrounding the North Pole – by allowing trees and shrubs into areas where they were previously unable to grow.

Below the surface

While much attention has been paid to how these above-ground changes, such as shrub growth and “Arctic greening”, could help to absorb carbon, the study’s authors argue that roots and the surrounding soil environment may be just as important in determining whether ecosystems become carbon sources or carbon sinks.

The paper was led by Rebecca Hewitt at Amherst College, USA, and co-led by Gesche Blume-Werry at Umeå University and Thomas Parker at The James Hutton Institute, UK, with contributions from eight other research organisations.

“Our paper highlights the central role of root and rhizosphere processes in feedbacks from the Arctic to the global climate, and we hope that it will inspire more research on this important, but understudied topic,” says Gesche Blume-Werry, Assistant Professor at the Department of Ecology, Environment and Geoscience at Umeå University.

The dual role of roots

The researchers found evidence that rising temperatures and permafrost thawing can alter root productivity and depth, as well as seasonal growth patterns and plant-soil interactions. 

While roots can help lock carbon into soils by supporting plant growth and contributing organic matter, they can also stimulate microbes that break down soil carbon and release greenhouse gases such as carbon dioxide and methane.

The review suggests that, because these processes can go both ways, improving climate predictions will require a better understanding of how plant roots, soil microbes and thawing permafrost interact.