Clear-cutting forests may be hurting these ecosystems more than we realized. Scientists have found that clear-cutting destabilizes carbon in forest soils, which could cause a greater release of this material.
Soil is the world's largest terrestrial carbon pool. In other words, it helps store the world's carbon instead of releasing it to the atmosphere. In northern hardwood forests in the U.S., in fact, mineral soil pools store up to 50 percent of total ecosystem carbon.
Examining how different soils store carbon is extremely important. This is largely because carbon storage can play a major role when it comes to curtailing climate change. Learning what techniques work and what don't could help researchers develop ways to store carbon more efficiently.
In this latest study, the researchers decided to see whether clear-cutting changed the strength of the chemical bonds of carbon stored in mineral soils in hardwood forests. This is particularly important since some areas experience clear cutting. Clear-cutting itself involves harvesting all timber from a site instead of selectively cutting mature trees. This, in turn, leaves the soil bare until new trees can colonize the area.
In this case, the scientists collected soils from recently clear-cut forests and from older forests. They also pulled carbon from the soil in a sequence of gentle to stronger extractions. This revealed that mature forest stored a lot more organic carbon in strongly mineral-bound and stable carbon pools than soils from cut forest.
"Clear-cutting forests has an effect of mobilizing the carbon, making it more likely to leave the soil and end up in the atmosphere," said Andrew Friedland, senior author of the study and a professor of environmental studies. "These findings are important because differences in the relative distribution of carbon in organo-mineral pools in mature and cut forests may inform our understanding of soil organic matter stability and bioavailability, microbial decomposition and carbon dioxide production in ecosystems after clear-cutting."
The results reveal that when it comes to storing carbon, clear-cutting is not the way to go. This is especially important when it comes to changing climate conditions.
The findings were recently published in the journal Soil Science.
