December 27th, 2012 by James Ayre
There is a enormous loss of microbial diversity and communities occurring in the Amazon being as a result of deforestation, new research has found. This is an extremely important finding, and an area of research that has mostly gone uninvestigated. Microbial organisms are an integral part of any healthy, functioning ecosystem, if a large enough loss of species and diversity occurred it could trigger profound changes in the future.
Related and somewhat recent research has implicated the lower diversity of microbial communities in urban and agricultural, rather than forested areas, in all manners of modern autoimmune diseases and cognitive defects, such as autism.
Klaus Nüsslein, of the University of Massachusetts, an expert in tropical rain forest microbial soil communities, says, “We found that after rainforest conversion to agricultural pastures, bacterial communities were significantly different from those of forest soils. 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.”
Along with his fellow researchers, he thoroughly investigated a large farm site over the past 4 years “at the frontier where farmers drive agriculture into pristine rainforest in Rondonia, Brazil, to convert rainforest to agricultural use. Findings in part validated previous research showing that bacteria in the soil became more diverse after conversion to pasture. However, in its fourth year, their study overcame limitations of earlier investigations to show that changes in microbial diversity occurred over larger geographic scales.”
“Findings do not support earlier study conclusions, instead they show that the loss of restricted ranges for different bacteria communities results 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. The researchers hope their work will provide valuable data to those making decisions about the future of the Amazon rainforest.”
Lead author Jorge Rodrigues of the University of Texas at Arlington says, “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. Now we know that microbial communities which are so important to the ecosystem also suffer significant losses.”
The researchers point out that one-third of world’s species live in the Amazon, and that with the rapid rate of deforestation there, all of these species will be lost. Currently agriculture is the primary driver of the deforestation there. Since agriculture is one of the largest sectors of Brazil’s economy, it could be very difficult to slow down the deforestation occurring there, much less stopping it completely.
“Rodrigues says he and colleagues are currently compiling findings about the potential for recovery of the microbial diversity after pastureland is abandoned and returned to ‘secondary forest.’ At the same time, Nüsslein and colleagues are leading an effort to investigate 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.
The research was just published in Resulthe current issue of Proceedings of the National Academy of Sciences.
Here’s some more information on deforestation in the Amazon:
“The main sources of deforestation in the Amazon Rainforest are human settlement and development of the land. In the nine years from 1991 to 2000, the total area of Amazon Rainforest cleared rose from 415,000 to 587,000 km²; comparable to Spain, Madagascar or Manitoba. Most of this lost forest has been replaced with pasture for cattle. In February 2008, the Brazilian government announced that the rate at which the Amazon rainforest was being destroyed had been accelerating noticeably during the time of the year that it normally slows: In just the last five months of 2007, more than 3,200 sq. kilometers, an area equivalent to the state of Rhode Island, was deforested. The Amazon rainforest continues to shrink but more recently the rate of deforestation has been slowing, with the 2011 figures showing the slowest rate of deforestation since records have been kept.”
Image Credits: UMASS Amherst; Jorge Rodrigues
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