Deforestation is fairly self-explanatory, but “forest degradation” is not quite as clear. As defined in the journal Ecology and Society, forest degradation is “a reduction in the capacity of a forest to produce ecosystem services such as carbon storage and wood products as a result of anthropogenic and environmental changes.” It is a more nuanced definition of deforestation, one that takes into account the ultimate costs of environmental damage.
A Brazilian study that will appear in the journal Global Change Biology states that forest degradation as a result of logging and fire creates additional “hidden” emissions that were previously incalculable.
Whereas deforestation can be tracked via satellite, degradation requires on-the-ground analysis to catch what satellites miss. After studying 70,000 trees and taking over 5,000 soil samples, researchers estimate that Brazilian forest degradation produces 40 percent of the carbon emissions of deforestation – in addition to current deforestation emissions. That would equal about 54 billion tonnes of carbon loss.
“It’s been completely overlooked,” says lead author Dr. Erika Berenguer from Lancaster University. “When we talk about deforestation, we completely remove the forest and all that carbon is lost. When you talk about degradation it is more cryptic. Chunks of the forest are affected but when you look from the satellite image you still see trees, you just don’t know the condition, and that is why it is overlooked.”
Berenguer’s study used four forest types to assess emissions: undisturbed sites, logged sites, logged and burned sites, and pastures that were returning to forests. According to Berenguer, the 54 billion tonnes of carbon loss from degradation occur “mainly [from] fires that escape from burning pasture, selective logging and edge effects…. [W]hen you fragment a forest, when it is close to a pasture, that border is subject to higher temperatures, higher winds and the forest starts dying out from the edge toward the core.”