Truths and Answers about the Amazon

The Amazon rainforest in South America plays a vital role in regulating Earth’s climate and is home to thousands of species of wildlife. But much of what is currently known about the Amazon is based on about 1,000 plots of land each the size of a football field. That may sound like a lot, but not if you consider the Amazon covers over 2 million square miles or about two-thirds the size of the continental U.S.

Dr. Kenneth Feeley looks up at a tree in the Amazon rain forest.
Dr. Kenneth Feeley, Smathers Chair in Tropical Trees at the University
of Miami College of Arts and Sciences. (Photo credit: Gary Braasch)

“You have the biggest rain forest in the world, and we’ve only studied 1,000 football fields of it,” said Dr. Kenneth Feeley, the Smathers Chair in Tropical Trees at the University of Miami College of Arts and Sciences, who studies the ecology of tropical forests.  

In a recent paper, “Ancient human disturbances may be skewing our understanding of Amazonian forests,” published in the journal Proceedings of the National Academy of Sciences, Feeley argues that not only have researchers just scratched the surface of analyzing the Amazon, but the plots of land that we do analyze may have biases that are not accounted for.

Namely, almost all of the plots are in areas with relatively “easy” access (for example, close to waterways or population centers) and have likely been impacted by humans for centuries.  

According to Feeley, native inhabitants of Amazonia actively transformed and modified the forests along the Amazon River and its tributaries before their populations collapsed around the arrival of Europeans in 1492 AD. Given the long lifespan of Amazonian trees, many of the forests that biologists are studying today may still be recovering from human disturbances, potentially skewing interpretations of their growth and our understanding of how the Amazon is responding to climate change.

Meanwhile, Feeley said the scientific community at large has spent less time studying the more remote parts of the Amazon that are harder to get to and hence less likely to have been impacted by ancient human activities. That doesn’t mean scholars and scientists should throw away all the research that’s been done, he says, but they should take the potential impacts of ancient humans into consideration and be careful about drawing conclusions based on current datasets.

For example, Feeley said, it is hypothesized that, with increasing carbon dioxide in the atmosphere, tropical forests are able to grow faster and take up more of that CO2, thereby buffering the climate from our increasing carbon emissions. However, Feeley said, the research to support that claim is largely attributed to measuring a relatively small sample of trees that may have been disturbed by humans 500 years ago. 

“How do we know those forests aren’t just recovering from that original disturbance?” he asked. “How do we know whether or not the rest of the Amazon is actually suffering under climate change and growing slower?  Until we are confident in the answers to these questions, we shouldn’t count on the Amazon to protect us against our increasing greenhouse gas emissions.”

Despite the large uncertainties, scientists and policy makers are continuing to make big judgments about the entire Amazon based off a relatively small and potentially compromised sample. With the publication of his paper, Feeley hopes to get funding that would help him and his colleagues investigate more diverse samples of land throughout the Amazon.

He isn’t under the illusion that researchers will ever be able to assess the entirety of the Amazon but believes that, with help, scientists like him can do a more accurate job and gain better insight into the workings of the Amazon.

“If you think of a phone survey where people call you to ask questions, they’re taking a small but systematic sample from all over the country and extrapolating out to the population,” he said. “That’s analogous to what we need to do. A more systematic or targeted sampling approach just might help us discover truths and answers about the Amazon and the Earth that we might’ve missed so far.”

Feeley’s research collaborators include Crystal McMichael from the Institute for Biodiversity and Ecosystem Dynamics at the University of Amsterdam, Frazer Matthews-Bird from the Department of Biological Sciences at Florida Institute of Technology, and William Farfan-Rios from the Department of Biology at Wake Forest University.


By Andrew Boryga

 

 

 

April 20, 2017