MELBOURNE, FLA. — Human influence across centuries continues to influence biodiversity and carbon storage in the world’s largest rainforest, according to a new international study led by the University of Amsterdam and Florida Tech. The study shows that the Amazon rainforest – often described as one of the Earth’s last untouched wildernesses – in fact still bears deep ecological imprints of both pre-Columbian Indigenous communities and European colonists.
Using cutting-edge spatial modeling and vast historical datasets, the researchers discovered that centuries of human settlement, cultivation and resource extraction have left lasting marks on the distribution of Amazonian tree species, which remain visible today.
“Our findings show that seemingly undisturbed parts of the Amazon have been shaped by people over hundreds or even thousands of years,” says lead author Crystal McMichael ’12 Ph.D., associate professor at University of Amsterdam’s Institute for Biodiversity and Ecosystem Dynamics.
And, added co-author Mark Bush, a professor and director of the Institute for Global Ecology at Florida Tech, “These invisible legacies may still be affecting ecosystem functioning as well as biodiversity – and the type of legacy likely depends on who lived there last.”
Ultimately, the research may help reframe the Amazon as a dynamic system of coexistence between people and nature – an evolving landscape that has been cultivated, abandoned and reborn many times over.
“To protect the Amazon’s future, we must first understand its past,” says McMichael. “Accounting for ancient and colonial legacies can help us better predict how forests will respond to deforestation, climate change, and reforestation efforts.”
Ancient Roots, Lasting Impacts
The research team combined data from over 7,000 archaeological sites with more than 100,000 digitized biodiversity records dating back to early European expeditions. By modeling human settlement patterns during the pre-Columbian era (before European contact) and the colonial era (1600–1920 CE, which includes European contact and the Amazon Rubber Boom), they mapped where human activity was most intense.
These historical models were then compared with tree data from 1,521 forest plots across the Amazon basin representing 262 dominant and useful species.
The results were striking: Because both indigenous and colonial populations tended to settle along major rivers, where fertile soils and access to trade routes supported larger communities, forests even today within about 6 miles (10 km) of these rivers show higher abundances of tree species that were once cultivated, harvested or otherwise favored by humans.
“Rivers have always been lifelines in the Amazon,” McMichael says. “They shaped how people moved, lived and interacted with the forest – and that history is still being written into the ecosystem.”
Enrichment and Depletion
The study found that human activity enriched the forest with multiple useful and now-iconic species. Trees such as the Brazil nut (Bertholettia excelsa), rubber (Hevea brasiliensis), and the murumuru palm (Astrocaryum murumuru) all flourished in areas with a long history of human presence. These species remain among the Amazon’s most economically and ecologically important species today.
In contrast, certain palms and hardwoods and other trees used in colonial construction appear to have declined in regions that experienced heavy exploitation during the colonial and Rubber Boom periods.
“Indigenous communities tended to manage forests in ways that increased biodiversity and sustainability,” says Hans ter Steege, senior researcher at Naturalis Biodiversity Center in Leiden, the Netherlands, and director of the Amazon Tree Diversity Network. “Later colonial industries often extracted resources more intensively, leaving behind ecological scars that are still healing.”
The study challenges the long-held notion that modern Amazonian forests are purely “natural” systems untouched by human hands. It also challenges the recent ideas that only pre-Columbian inhabitants of Amazonia shaped the forests. Instead, this helps us understand the forests are living mosaics of ecological and cultural history that has been written and rewritten over centuries and millennia.
The researchers argue that recognizing these legacies is crucial for improving conservation and climate models, which often assume that old-growth forests have remained undisturbed for thousands of years.
