Amazon’s diversity loss shows up in the soil

Researchers worry that a loss of genetic variation in microbial communities in the Amazon’s converted agricultural land could negatively affect the entire ecosystem.

An international team of researchers has identified a new concern about deforestation in the Amazon rainforest—a troubling loss in the diversity among the microbial organisms responsible for a functioning ecosystem.

Researchers analyzed soil samples from an area near Rondônia, Brazil, where rainforest has been converted to agricultural use. Image credit: Paulo Fehlauer

The group sampled a 100 square kilometer area, about 38 square miles, in the Fazenda Nova Vida site in Rondônia, Brazil, a location where rainforest has been converted to agricultural use.

The findings, in part, validate previous research showing bacteria in the soil became more diverse over the years as it was converted to pasture.

Read the original study

But the results contradict prior thinking by showing that the loss of restricted ranges for different kinds of bacteria communities resulted in a biotic homogenization and net loss of diversity overall.

Scientists worry that the loss of genetic variation in bacteria across a converted forest could reduce ecosystem resilience.

“We have known for a long time that conversion of rainforest land in the Amazon for agriculture results in a loss of biodiversity in plants and animals,” says lead researcher Jorge Rordigues from the University of Texas at Arlington. “Now we know that microbial communities, which are so important to the ecosystem, also suffer significant losses.”

The new research is described in a paper published in the Proceedings of the National Academy of Sciences.
Team member James Tiedje, an Michigan State University professor of crop and soil sciences, says the study was unique because of its large scale. “The systematic and large-scale sampling design of this study gave us the power to see the homogenization,” he says.

Grants from the USDA National Institute of Food and Agriculture, Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, and the Fundação de Amparo à Pesquisa do Estado de São Paulo supported the work.