Study reveals how 500 years of human exploitation has created a dangerous 'extinction vortex' in one of the world's most important forests

Courtesy of Photo Mariana Landis/ Wildlife Ecology, Management, and Conservation Lab (LEMaC)Brachyteles arachnoides, or a charcoal monkey, pictured in Brazil in 2011.
  • New research shows mammal populations in Brazil’s Atlantic Forest have been cut in half after centuries of human exploitation.
  • The forest has been reduced from 1.1 million square kilometers to just 0.143 square kilometers since colonization in the 16th century.
  • The lead author on the study said the forest was trapped in an “open-ended extinction vortex.”

Centuries of human exploitation in Brazil’s Atlantic Forest – one of the world’s most important forests – has left it nearly empty, according to new research.

More than half of the subtropical forest’s local mammal species have been wiped out since Europeans colonised the region in the 16th century, according to the study published in the journal PLoS ONE on Tuesday.

The forest has been reduced from over 1.1 million square kilometers to just 0.143 square kilometers since colonization in the 16th century, largely from human activities such as logging and farming. And those activities have severely harmed the forest’s biodiversity.

“These habitats are now often severely incomplete, restricted to insufficiently large forest remnants, and trapped in an open-ended extinction vortex. This collapse is unprecedented in both history and pre-history and can be directly attributed to human activity,” Carlos Peres, a biologist at the University of East Anglia and a lead author on the study, said in a statement.

Brazil's subtropical Atlantic ForestCourtesy of the University of East AngliaBrazil’s subtropical Atlantic Forest.

To understand how humans have impacted local mammal populations, the researchers compared inventories of large and medium-sized mammals in the forest from the past 30 years, with baseline records from when the area was first colonised by Europeans in the 16th century.

The researchers looked at individual species, as well as groups of ecologically related species to see which had been impacted the most.

Apex predators, like jaguars and pumas, as well as large-bodied herbivores like tapirs, were among the hardest hit.

Mammals play a critical role in forest ecology, particularly by regulating prey populations and helping plants disperse their seeds with their excrement, according to the study.

“The mammalian diversity of the once majestic Atlantic Forest has been largely reduced to a pale shadow of its former self,” Peres said.

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