Amazon deforestation affects more than originally thought

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Dr. TiedjeAn international team of researchers has revealed a new concern about deforestation in the Amazon rainforest – a troubling loss in the diversity among the microbial organisms responsible for a functioning ecosystem.

The group, which includes MSU AgBioResearch scientist James Tiedje, sampled a 100-square kilometer area, about 38 square miles, in the Fazenda Nova Vida site in Rondônia, Brazil, a location where the rainforest has been converted to agricultural use. The findings in part validated previous research showing bacteria in the soil became more diverse over the years as it was converted to pasture.

But their findings contradicted 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,” said 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 appearing in the online publication of the Proceedings of the National Academy of Sciences.

Tiedje, an university distinguished professor of microbiology and molecular genetics and of crop and soil sciences and director of the MSU Center for Microbial Ecology, said 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 said.

The research team’s work was supported by 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.

Other members of the research team were from the universities of Oregon, Massachusetts and Sao Paulo.

Photo:  Dr. Tiedje is University Distinguished Professor of Microbiology and Molecular Genetics, and of Crop and Soil Sciences, and is Director of the Center for Microbial Ecology at Michigan State University.

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