Forests in the Amazon lost 974 million tons of carbon at their edges between 2011 and 2015, with a third of that damage due to deforestation, according to a study published this Wednesday in the journal Science Advances.
“Deforestation is the main cause of carbon losses in tropical forests, but it does not operate alone,” indicated the study led by Celso HL Silva, from the Laboratory of Tropical Ecosystems and Environmental Sciences in Sao Jose Dos Campos (Brazil).
The fragmentation of forests, which is a characteristic of the deforestation process, “promotes indirect carbon losses induced by the effect on the edges of the forest”, a process that policies for reducing carbon emissions do not take into account in the tropics, the scientists explained.
In the Amazon, which is the world’s largest continuous tropical forest, deforestation has steadily converted old-growth forests into areas devoted to agriculture and cattle ranching, which has extensively fragmented landscape.
This fragmentation contributes to the increase in the number of separated wooded areas with the result of an increase in the perimeters and extension of the forest edges.
These changes in the configuration of the forest cover cause direct carbon losses due to the effect of the edges and the incursion of the fires caused to open new areas to agriculture and livestock.
“The exposure of the Earth’s forests to the edge effect is widespread,” the article added. “Globally, 70% of the forests were located within one kilometer from the forest edges in 2000. However, only 5.2% of the forests in the Brazilian Amazon were within this same edge zone in 2014.”
The findings of this research point to fragile deforested edges as a significant, and as yet unmeasured, source of carbon loss.
The researchers noted that while carbon loss due to deforestation in the Amazon decreased by about 7 million tonnes per year between 2001 and 2015, carbon losses at forest edges remained unchanged.
Tropical forests, which store more than half of the carbon on the planet’s surface, have decreased by 10% between 1990 and 2015, due to human activities, the scientists indicated.
But it is not only the reduction of forests that worries researchers, but the fragmentation that results when logging, burning and agricultural activities leave “patches” of forests isolated from each other, with the trees on the edges exposed to turbulent winds and increased fire hazards.
To measure how forest fragmentation contributes to carbon losses from deforestation, Silva and his colleagues processed data collected by airplanes, measuring distances using lasers, to model carbon loss as a function of the age of the trees. wooded borders.
They then applied this model on maps documenting the age of remotely sensed forest edges between 2000 and 2015 to visualize edge-induced carbon loss in the region.
The researchers concluded that efforts such as landscape planning could help account for the huge loss of carbon at the edges of fragmented forests, and noted that this source of emissions makes it difficult to achieve the targets set under the Agreement. from Paris.
With information from EFE