Monitoring carbon in forest and grassland soils

Whilst trees store large amounts of carbon in their roots, trunks and branches, soil is also a major reservoir of carbon in forests. Boreal forests, which cover much of the Northern Hemisphere, store between 20% and 30% of all terrestrial carbon.

In Norway, scientists estimate that forest soil contains approximately three times as much carbon as the trees above ground. However, estimates of soil carbon in Norwegian forests vary substantially between studies. Moreover, there is no comprehensive record of how soil carbon stock has changed over time, leaving considerable uncertainty.

To address this uncertainty, efforts are now underway. In 2022, NIBIO was commissioned to launch a nationwide monitoring programme for soil carbon in forests and grasslands. The plan is to survey 3,000 forest sites and 300 grassland sites nationwide by 2033, with approximately 330 sites being visited annually. The goal is to determine how much carbon is stored in forest and grassland soils and how this storage changes over time.

The monitoring sites are systematically distributed along a grid across the country, ensuring statistically representative sampling.

"This newly launched national soil carbon monitoring programme will offer valuable insights into soil carbon storage in Norwegian forests, contributing significantly to Norway's greenhouse gas accounting," says NIBIO researcher Dr Shun Hasegawa.

The survey sites will be revisited every ten years to detect changes in soil carbon stock over time. Thus, the soil carbon monitoring programme will serve as a foundation for further research on soil carbon dynamics.