December 24, 2012
Conversion of Amazon forest for cattle pasture in Brazil.
Sampling 100 square kilometers (38 sq miles) of forested land converted to cattle pasture, a team of scientists found that deforestation leads to "biotic homogenization and net loss of diversity" of soil bacteria. The results suggest the decline in biodiversity may reduce the ability of forest areas to recover as well as the ability of deforested land to sustain agriculture.
"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," said lead author Jorge Rodrigues of the University of Texas at Arlington.
"The combination of loss of forest species and the homogenization of pasture communities together signal that this ecosystem is now a lot less capable to deal with additional outside stress," added co-author Klaus Nüsslein, a microbiologist at the University of Massachusetts.
Some of the researchers are now working to determine whether microbial diversity recovers when pastureland is abandoned and secondary forest regrows.
"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.
CITATION: Rodrigues et al. Conversion of the Amazon rainforest to agriculture results in biotic homogenization of soil bacterial communities. PNAS. Dec 28, 2012.