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Humans are destroying what's left of the Amazon

Concern for the status of the Amazon rainforest usually centers on understanding the extent of deforestation and its devastating consequences. But this may only be part of the story. The authors of a new review article, published in the journal Science, say that about 2.5 million square kilometers of the Amazon (that is almost 40 percent of remaining rainforest), is degraded by the impacts of human activities. 

The review used data from previously published scientific studies and satellite imagery to identify the changes in the Amazon region between 2001 and 2018. Thirty-five researchers were involved, from institutions such as Brazil’s University of Campinas (Unicamp), the Amazon Environmental Research Institute (IPAM), National Institute for Space Research (INPE), and UK’s Lancaster University. The work is the result of the AIMES (Analysis, Integration and Modelling of the Earth System) project, linked to the Future Earth international initiative, which brings together scientists and researchers who study sustainability.

The authors define the concept of degradation as transient or long-term changes in forest conditions, caused by humans. Degradation is different from deforestation, where the forest is removed altogether and a new land use, such as agriculture, is established in its place. Although highly degraded forests can lose almost all of the trees and animal species, the land use itself does not change.

In addition, the activities that lead to the degradation of forests can also generate carbon emissions; these are equivalent to or even greater than the emissions arising from deforestation itself. The authors identify four key disturbances driving forest degradation: forest fires, edge effects (changes that occur in forests adjacent to deforested areas), selective logging (such as illegal logging) and extreme drought. They also consider the effects of other, less well-studied factors such as habitat fragmentation. Different forest areas can be affected by one or more of these disturbances.

“Despite uncertainty about the total effect of these disturbances, it is clear that their cumulative effect can be as important as deforestation, for carbon emissions and biodiversity loss,” said study co-author Jos Barlow, a professor of conservation science at Lancaster University.

The Amazon rainforest is a vital, yet vulnerable, major ecosystem on Earth. It provides crucial global ecosystem services that help maintain the planet’s carbon and water cycles, and is home to a staggering one-third of all known species. Modern agricultural and industrial practices, along with changes brought about by global warming, are degrading Amazonian environments at a very rapid pace. 

The scientists assess that the degradation of the Amazon also has significant socioeconomic impacts, which should be further investigated in the future.

“Degradation benefits the few, but places important burdens on many,” said Dr. Rachel Carmenta, a co-author based at the University of East Anglia. “Few people profit from the degradation processes, yet many lose out across all dimensions of human well-being – including health, nutrition and the place attachments held for the forest landscapes where they live. Furthermore, many of these burdens are hidden at present; recognizing them will help enable better governance with social justice at the center.”

According to the researchers, these degradation factors will continue to produce carbon emissions that will affect the atmosphere, irrespective of whether deforestation is halted in the Amazon. 

“Even in an optimistic scenario, when there is no more deforestation, the effects of climate change will see degradation of the forest continue, leading to further carbon emissions,” said Dr. David Lapola, leader of the study and researcher at the Centre for Meteorological and Climatic Research Applied to Agriculture at Unicamp. However, “… preventing the advance of deforestation remains vital, and could also allow more attention to be directed to other drivers of forest degradation.”

The authors propose creating a monitoring system for forest degradation, as well as prevention and curbing of illegal logging and controlling the use of fire. One suggestion is the concept of “smart forests” which, like the idea of “smart cities,” would use different types of technologies and sensors to collect useful data in order to improve the quality of the environment.

Dr. Lapola and colleagues emphasize that policies to halt deforestation will not necessarily address the factors that cause degradation to remaining forest. These policies must therefore be complemented by other approaches to curb the disturbances that degrade the remaining forest ecosystems. 

“Public and private actions and policies to curb deforestation will not necessarily address degradation as well,” said Dr. Lapola. “It is necessary to invest in innovative strategies.”

By Alison Bosman, Staff Writer

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