Up to 64 percent of above-ground biomass in selectively logged forests may consist of dead wood left over from logging damage, argues a paper published this week in Environmental Research Letters.
The research is based on field work conducted in Malaysian Borneo under the Stability of Altered Forest Ecosystems (SAFE) project, an initiative that is studying the ecological impacts of forest conversion for oil palm plantations. A team of scientists led by Marion Pfeifer of Imperial College London assessed the amount of carbon stored in dead wood after high value timber was selectively extracted. They found that the amount of dead wood is significantly higher than generally assumed.
“I was surprised by how much of the biomass dead wood accounted for in badly logged forests,” said Pfeifer in a statement.
Selective logging in Sabah, Malaysia. Photos by Rhett A. Butler
The findings have potential implications for modeling emissions associated with selective logging, an activity that is sometimes promoted by the forestry sector and some conservation groups as an ecologically benign activity.
Given that up to a third of tropical forests worldwide are selectively logged, the undercounted emissions could be substantial, according to Pfeifer.
“That such logged forests are not properly accounted for in carbon calculations is a significant factor,” Pfeifer explained. “It means that a large proportion of forests worldwide are less of a sink and more of a source, especially immediately following logging, as carbon dioxide is released from the dead wood during decomposition.”
“Selectively-logged tropical forests now make up about 30 per cent of rainforests worldwide. This means such global calculations are wrong at least 30 per cent of the time,” she added.
However, the study didn’t put a precise number on how the extent to which emissions from selective logging may be undercounted worldwide. The authors said more work needs to be done to understand rates of decomposition to estimate emissions.
CITATION: Pfeifer et al. ‘Deadwood biomass: an underestimated carbon stock in degraded tropical forests? ‘ Environ, Res. Lett., 2015