The research, published in Nature, combined satellite data of Amazon fires with detailed maps showing the geographic ranges of 11,514 plant and 3,079 animal species.
The results show that between 77 and 85 per cent of species identified as threatened by the International Union for Conservation of Nature (IUCN) lost at least part of their habitat to fires between 2001 and 2019.
This includes 236 of the 264 IUCN-listed plant species, 83 of 85 bird species, 53 of 55 mammal species, five of nine reptile species and 95 of 107 amphibian species.
The Amazon is home to 40 per cent of the world’s tropical forests, carbon-rich ecosystems crucial to battling the climate crisis, and 10 per cent of all known species.
Most fires in the typically wet ecosystem are started intentionally by humans profiting from activities such as cattle ranching, logging and mining.
Dr Xiao Feng, study lead author and an assistant professor at Florida State University, told The Independent: “We found most of the plant and vertebrate species [in the Amazon] were impacted by fires over the past two decades.
“While the impacts are small for many species, the higher impacts are associated with species with restricted ranges, including rare species and threatened species.”
Such species include Remijia kuhlmannii, a rare tree that grows only in the southern Brazilian Amazon. The research found that up to 60 per cent of the tree’s geographic range was impacted by fires in the past two decades.
The research also found that the impact of fires on the Amazon’s plant and animal species is increasing steadily over time.
“The impact on Amazon biodiversity has not stopped, it is continuously increasing,” said Dr Feng.
As well as studying the impact of fires on the geographic range of threatened species, the research team also studied how droughts and changes in Brazilian forest policy moderated the reach of fires.
The findings show that strengthened forest policies introduced by Brazil in the mid-2000s corresponded with reduced rates of forest burning.
However, relaxed enforcement of these policies in 2019 – under the leadership of Brazilian president Jair Bolsonaro – has “seemingly begun to reverse this trend”, the scientists say.
“The fires, as well as their impact on biodiversity, are sensitive to forest policies,” said Dr Feng.
The study found that up to 10,343 square kilometres of forest were affected by fires in 2019 – an area up to 28 per cent higher than expected.
These fires lead to “some of the most severe potential impacts on biodiversity since 2009”, the researchers said.
The findings come as Mr Bolsonaro is facing increasing international pressure over his environmental policies.
On Friday, a letter to Mr Bolsonaro from a cross-party group of 30 UK MPs shared with The Independent condemned his ongoing “assault on the Amazon” and warned that the UK government is “complicit”.
The findings also arrive shortly after another Nature study found that huge swathes of the Amazon rainforest now emit more carbon than they are able to absorb as a result of deforestation and fires.
Prof Thomas Gillespie, a biodiversity researcher from the University of California, Los Angeles who was not involved in the study, said the findings were “exciting”.
“One of the most exciting aspects of the study is simply the number of species whose ranges are collected, modelled and compared,” he wrote in a News & Views article accompanying the new research.
“Standardising the scientific names and determining the locations of more than 11,000 plant species is in itself no small task.”