The thousands of fires burning in the Amazon do not look like the major forest fires of Europe or North America - instead, they are fuelled mainly by branches, vegetation and other byproducts of deforestation in cleared areas, experts say.

The dramatic scale of this year's fires is the result of a significant acceleration of deforestation for the lumber industry, for agriculture or for other human activities.

"In the tropics, fire is used extensively in a land-use environment," said Jeffrey Chambers, a scientist at the Lawrence Berkeley National Laboratory in California and a specialist in rainforests.

"It's how you get rid of your agricultural waste products... And part of the reason why that works is because those fires don't generally move into the forest," he explained.

"A tropical rainforest is generally not flammable" because it is so humid.

California has the opposite problem: burning waste is prohibited because the forests are so dry, they could go up in flames at the smallest spark.

But in the Amazon, when an area of forest is cleared, the tree trunks are removed and the rest of the vegetation is burned on the spot during the dry season, which lasts from July to November.

For farmland, or for prairies, brush and weeds alike are heaped together, waiting for the dry season. That is what is burning right now.

Even when the fire manages to penetrate the dense forest - called "primary" when it is still untouched - it usually stays in the vegetation at ground level and generally does not reach the treetops, about 30m up.

The effect is just as devastating, though, because the tree trunks are damaged at ground level, but the overall image differs vastly from the massive fires that Europeans or Americans are used to seeing.

Human use of fire to manage land explains the astronomical number of fires - more than 75,000 - recorded by Brazilian authorities since January.


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How global appetite for beef and soy fuels Amazon fires

Two of the industries involved in the infernos consuming the Amazon rainforest and drawing the attention of global powers gathered at the G7 meeting in France are familiar to diners worldwide: soy and beef.

Beef  

Brazil is the world's largest exporter of beef, with a record 1.64 million tons sent to its top markets China, Egypt and the European Union in 2018, according to the Brazilian Beef Exporters Association.

The country has seen its production surge over the past two decades, with exports measured in both weight and value increasing by 10 times between 1997 and 2016, led by three behemoth companies: JBS, Minerva and Marfrig.

All this growth has come at the expense of the Amazon.

"Extensive cattle farming is the main driver of deforestation in the Amazon, with just over 65% of deforested land in the Amazon now being grazed," according to Romulo Batista, a researcher at Greenpeace.

Soy

Soybeans, a major cash crop for Brazil, were also once a major contributor to deforestation.

The crop saw a dramatic rise in cultivation in the 1970s, fuelled by the migration of farmers, the development of new cultivation techniques and the use of pesticides.

Brazil exported a record 83.3 million tons of the crop in 2018, up 22.2% from 2017, according to Brazil's economy ministry.

The country is the top supplier of soybeans to the United States, but sends the most overall to China.

Brazilian soybean exports to China jumped nearly 30% last year thanks to the trade dispute with Washington that pushed Beijing to look for other sources of the crop it uses to feed cattle.

Soy plants in a field in a deforested section of the Amazon rainforest in Rondonia state, Brazil

About 6.5% of the deforested area in the Amazon is used for agriculture, but the contribution of soybeans to that has decreased over time.

A moratorium on buying soy from newly deforested areas came into force in 2006, and "less than two percent of the soya planted in the Amazon comes from deforested areas since 2008," Mr Batista said.

However, other forests in Brazil such as the Cerrado are being cleared for soybean cultivation. In June, Greenpeace denounced Europe's "addiction" to Brazilian soy used for pig and poultry farms.