Plant roots and the soil surrounding them could play a major role in how Arctic tundra ecosystems respond to climate change, according to a review published in Nature Reviews Earth & Environment. The researchers say these belowground processes may help clarify whether the changing tundra acts as a carbon sink or a source of greenhouse gases.
Arctic permafrost contains an estimated 1,460 to 1,600 billion metric tons of organic carbon—about twice the amount currently in the atmosphere. As permafrost thaws, some of that carbon is released. Thawing is also changing the treeless tundra around the North Pole, allowing trees and shrubs to grow in places where they previously could not.
While research has often focused on aboveground changes such as shrub growth and Arctic greening, the review highlights the importance of roots and their interactions with soil. The authors found evidence that rising temperatures and thawing permafrost can affect root productivity and depth, seasonal growth patterns, and relationships between plants and soil.
Roots can help retain carbon in soil by supporting plant growth and adding organic matter. But they can also stimulate microbes that break down soil carbon and release greenhouse gases, including carbon dioxide and methane. The effects can therefore point in either direction, the researchers say, making it important to understand how roots, soil microbes and thawing permafrost interact when improving climate predictions.
The review was led by Rebecca Hewitt of Amherst College and co-led by Gesche Blume-Werry of Umeå University and Thomas Parker of The James Hutton Institute, with contributions from eight other research organizations. The paper is titled “The Arctic carbon cycle response to changing root and rhizosphere processes amid greening and permafrost thaw.”
Sources: Phys.org.