Human Impact on Amazon Rainforest Grossly Underestimated

Human impact on the Amazon rainforest has been grossly underestimated, according to an international team of researchers.

The report detailed in the journal Global Change Biology says that selective logging and surface wildfires can amount to an annual loss of 54 billion tons of carbon from the Brazilian Amazon - that's equivalent to 40 percent of the yearly carbon loss from deforestation.

Researchers estimated both above and below-ground carbon loss from selective logging and ground level forest fires in the tropics using data from 70,000 sampled trees and thousands of soil, litter and dead wood samples from 225 sites in the eastern Amazon.

Deforestation leads to such large amounts of carbon loss - which in turn increases greenhouse gas emissions - starting with logging of prized trees such as mahogany and ipe. The removal of these trees impacts and damages neighboring trees.

With so many trees down a gap in the canopy opens, letting in more wind and sun that dries out the forest and makes it susceptible to wildfires.

The combination of selective logging and wildfire damage turns these once lush rainforests into measly scrubs of smaller trees and vines, which stores 40 percent less carbon than undisturbed forests.

Prior efforts to protect such rainforests have only focused on decreasing the levels of deforestation without considering the harmful effects of wildfires too.

"The impacts of fire and logging in tropical forests have always been largely overlooked by both the scientific community and policy makers who are primarily concerned with deforestation," lead researcher Dr. Erika Berenguer from Lancaster University said in a statement. "Yet our results show how these disturbances can severely degrade the forest, with huge amounts of carbon being transferred from plant matter straight into the atmosphere."

Co-author Dr. Joice Ferreira from Embrapa in Brazil, added:

"Our findings also draw attention to the necessity for Brazil to implement more effective policies for reducing the use of fire in agriculture, as fires can both devastate private property, and escape into surrounding forests causing widespread degradation. Bringing fire and illegal logging under control is key to reaching our national commitment to reducing carbon emissions."