Selective logging, partial destruction by burning, and fragmentation resulting from the development of pastures and plantations in the Amazon rainforest has resulted in an annual loss of 54 million tons of carbon, demonstrating how significant such practices are in terms of global warming.
This total represents up to 40 percent of the carbon loss caused by deforestation in the region, and yet these practices are not at the forefront of people's minds when it comes to greenhouse gas emissions and conserving the Amazon.
"The impacts of timber extraction, burning and fragmentation have received little notice because all the efforts have been focused on preventing further deforestation," first author Erika Berenguer of the UK's Lancaster University said in a statement. "However, our study has shown that this other type of degradation is having a severe impact on the forest, with enormous quantities of previously stored carbon being lost into the atmosphere."
Still, the study does not belittle efforts to halt deforestation - rates have fallen more than 70 percent over the last decade thanks to conservation efforts.
One of the reasons that this particular type of degradation has gone unnoticed is because it is difficult to monitor.
"Satellite imagery allows much easier detection of areas that are totally deforested," co-author Joice Ferreira explained.
So for this study, published in the journal Global Change Biology, researchers combined satellite imagery with field study to assess damage over the last 20 years to Santarém and Paragominas regions, located in the eastern part of the Amazon.
"We collected data from more than 70,000 trees and took more than 5,000 samples of soil, dead wood and other components of what is known as carbon stock. It was the largest study conducted to date regarding carbon loss from tropical forests due to selective logging and wildfires," Ferreira said.
Researchers concluded their study by saying that forests that were disturbed by logging or fire had from 18 percent to 57 percent less carbon than those that were untouched.