Researchers: Amazon deforestation is devastating microbial communities

December 26, 2012

Researchers: Amazon deforestation is devastating microbial communities

Researchers find evidence that Amazon deforestation is devastating microbial communities.

Researchers at the University of Massachusetts at Amherst have uncovered evidence that suggests that Amazon deforestation is devastating microbial communities.

“We found that after rainforest conversion to agricultural pastures, bacterial communities were significantly different from those of forest soils,” says Klaus Nüsslein of UMass. “Not only did the pasture soils show increased species numbers, these species were also less related to one another than in rainforest soil. This is important because the combination of lost forest species and the homogenization of pasture communities together signal that this ecosystem is now a lot less capable of dealing with additional outside stress.”

Mr. Nüsslein and his colleagues note that these microbial communities, currently being devastated by Amazon deforestation, have a large role to play in a functioning ecosystem.

The researchers examined a big farm site over the past four years in Rondonia, Brazil, where farmers push agriculture into virgin rainforest to convert rainforest to agricultural use. They confirmed previous research revealing that bacteria in the soil became more diverse after conversion to pasture. However, in its final year, their study showed that changes in microbial diversity took place over larger geographic scales.

The study’s findings, however, do not support previous study inclusions, instead they suggest that the loss of restricted ranges for different bacteria communities leads to a biotic homogenization and net loss of diversity overall. Researchers are very concerned that the loss of genetic variation in bacteria across a forest converted to agricultural use could negatively impact ecosystem resilience. Researchers hope that their data will provide valuable information to those deciding the fate of the Amazon rainforest.

“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,” biologist and first author Jorge Rodrigues of the University of Texas at Arlington says. “Now we know that microbial communities which are so important to the ecosystem also suffer significant losses.”

Researchers note that the Amazon contains fifty percent of the world’s rainforest and is home to 33 percent of Earth’s species. Unfortunately, the Amazon has one of the world’s highest rates of deforestation. While agriculture is essential to Brazil’s economy, researchers contend that the issue of Amazon deforestation must be tackled despite the economic and political obstacles that often block viable solutions.

According to a New York Times article from November, the “surging population growth of cities” is stressing the resources of the Amazon. “More population leads to more deforestation,” Philip M. Fearnside, a researcher at the National Institute for Amazon Research in Manaus, told the newspaper.

The researchers are conducting further studies to determine the potential for recovery of the microbial diversity after pastureland is no longer occupied and becomes “secondary forest.” Mr. Nüsslein and his colleagues are also looking into “how the redundancy of functions provided by soil microbes provides resilience to the effects of agricultural land use change to support a stressed ecosystem to recover stability.”

“Whether bacterial diversity will completely recover from ecosystem conversion will depend in part on whether the taxa lost due to conversion are truly locally extinct or whether they are present in the pasture sites but of such low abundance that they are undetectable in our study,” the authors write in their study.

The study’s findings are described in detail in the journal Proceedings of the National Academy of Sciences.


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