title: Land use intensification in the humid tropics increased both alpha and beta diversity of soil bacteria.
abstract: Anthropogenic pressures on tropical forests are rapidly intensifying, but our understanding of their implications for biological diversity is still very limited, especially with regard to soil biota, and in particular soil bacterial communities. Here we evaluated bacterial community composition and diversity across a gradient of land use intensity in the eastern Amazon from undisturbed primary forest, through primary forests varyingly disturbed by fire, regenerating secondary forest, pasture, and mechanized agriculture. Soil bacteria were assessed by paired-end Illumina sequencing of 16S rRNA gene fragments (V4 region). The resulting sequences were clustered into operational taxonomic units (OTU) at a 97% similarity threshold. Land use intensification increased the observed bacterial diversity (both OTU richness and community heterogeneity across space) and this effect was strongly associated with changes in soil pH. Moreover, land use intensification and subsequent changes in soil fertility, especially pH, altered the bacterial community composition, with pastures and areas of mechanized agriculture displaying the most contrasting communities in relation to undisturbed primary forest. Together, these results indicate that tropical forest conversion impacts soil bacteria not through loss of diversity, as previously thought, but mainly by imposing marked shifts on bacterial community composition, with unknown yet potentially important implications for ecological functions and services performed by these communities.
authors.affiliation: Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras, Minas Gerais, 37200-000, Brazil.|Lancaster Environment Centre, Lancaster University, Bailrigg, Lancaster, LA14YQ, United Kingdom.
authors.forename: Teotonio Soares
authors.initials: TS
authors.lastname: de Carvalho
authors.affiliation: Embrapa Agrobiologia, CNPAB, Rodovia BR 465, Km 7, Seropédica, Rio de Janeiro, CEP 23891-000, Brazil.
authors.forename: Ederson da Conceição
authors.initials: ED
authors.lastname: Jesus
authors.affiliation: Lancaster Environment Centre, Lancaster University, Bailrigg, Lancaster, LA14YQ, United Kingdom.|Museu Paraense Emilio Goeldi, Avenida Magalhães Barata, 376, Belém, Pará, Brazil.
authors.forename: Jos
authors.initials: J
authors.lastname: Barlow
authors.affiliation: Stockholm Environment Institute, Linnégatan 87D, Box 24218, Stockholm, 10451, Sweden.
authors.forename: Toby A
authors.initials: TA
authors.lastname: Gardner
authors.affiliation: Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras, Minas Gerais, 37200-000, Brazil.
authors.forename: Isaac Carvalho
authors.initials: IC
authors.lastname: Soares
authors.affiliation: Center for Microbial Ecology, Michigan State University, East Lansing, Michigan, 48824, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Tiedje
authors.affiliation: Departamento de Ciência do Solo, Universidade Federal de Lavras, Lavras, Minas Gerais, 37200-000, Brazil.
authors.forename: Fatima Maria de Souza
authors.initials: FM
authors.lastname: Moreira
mesh_terms: D000383:Agriculture; D001419:Bacteria / Q000235:genetics; D044822:Biodiversity; D065928:Forests; D012336:RNA, Ribosomal, 16S; D012987:Soil; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D012987:Soil
keywords: 16S rRNA gene; Amazon forest; below-ground biodiversity; drivers of bacterial community composition; high-throughput sequencing