The importance of deep roots in the carbon-climate feedback from thawing permafrost soils
In this project, we study how deep roots may influence carbon storage and release in arctic tundra
Around 80% of plant biomass in arctic tundra is belowground and roots are transporting carbon taken up by leaves into the soil. This carbon can increase soil carbon storage, but it can also stimulate releases of millennia-old soil carbon to the atmosphere. Here, deep roots may be particularly important as they interact with newly-thawed permafrost soils, which had been cut off plant influences since thousands of years. Yet, few arctic studies include root measurements, let alone in deeper soils, because they are hidden from view and difficult to study.
Permafrost soils contain twice as much carbon as the atmosphere, which they have protected for millennia. As arctic temperatures soar and the rate of permafrost thaw accelerates, there is a growing concern about large carbon losses from permafrost soils into the atmosphere. Even though around 80% of plant biomass in the arctic tundra is belowground, the crucial role of roots in carbon cycling remains unquantified. Roots can promote new carbon storage but also stimulate losses of old soil carbon. Here, deep roots are likely to be disproportionally important, as they increasingly interact with newly-thawed, vulnerable soils. Yet, few studies include root measurements, particularly in deeper soils. In this project we will quantify the role of deep roots in the carbon-climate feedback from thawing permafrost soils by using a long-term field experiment and controlled climate chamber experiments. Our results will help to define the importance of root dynamics in deep soils and improve our ability to predict feedbacks from arctic tundra to climate change.