Forest soil limits climate change? Scientists study methane absorption

Forest soils do more for our planet’s climate than we previously thought, silently absorbing methane from the air. New long-term measurements from southeastern Germany show that the uptake of this gas is increasing rather than decreasing over time.

Forest soils absorb methane. More and more every year

Scientists from the University of Göttingen have been tracking methane movements in 13 forest plots for nearly 25 years. During this time, they noticed that soils increased its absorption by an average of 3 percent per year.

This steady increase – observed in both dry and wet periods, along with gradually warmer conditions – challenges simple assumptions that climate change will uniformly reduce the ability of soils to act as methane reservoirs. It also raises new questions about why some forests perform better in this regard than others.

German scientists cite the structure of warmer and drier soil as one explanation. They believe it allows more air to pass through, allowing methane to move deeper into the earth faster instead of hanging near the surface.

Drier soil also keeps more pores filled with air, which helps both methane and oxygen move through the soil. This is a key factor because microorganisms need oxygen to consume methane.

Forests “buy us time” in the fight against climate change

Scientists conclude that warmer soils speed up their metabolism, thus matching the continuing increase in methane intake in many of the study sites. However, they point out that extremely dry conditions can inhibit the activity of microorganisms, while long periods of moisture put them in a much better position.

Researchers emphasize that the absorption of methane by the soil noticeably reduces the amount of greenhouse gases that enter the atmosphere. Depending on the weather, this could significantly reduce the pressure on the environment caused by the greenhouse effect. This does not completely solve the problem, but it saves time when introducing new methods of reducing emissions.

German scientists point out that the measurement results vary greatly depending on the regions studied. They emphasize that disruptions in forest activity have a strong impact on the ability to absorb methane. For example, bark beetle infestations and mass cutting down of diseased trees limit the absorption of gases. Even though the ground heats up faster, heavy logging equipment presses down on the soil, closing the tiny pores that methane needs to penetrate.