Soil bacterial diversities and response to deforestation, land use and burning in North Amazon, Brazil

The biodiversity in Amazon forest soils is continuously challenged by anthropogenic activities or disturbances, impacting the quantity and quality of its natural resources and a wide range of ecosystem services. Understanding microbial processes and response to various soil management practices provide valuable information to maintain sustainable ecological environments. We hypothesized that microbial assemblages (several not yet identified) and activities are continuously changing in forest ecosystems, mostly due to management selections. Therefore, our work's objective was to assess bacteria communities' changes via next-generation sequencing techniques and bridge knowledge gaps in our understanding of their responses to deforestations, intensive agriculture, and repeated forest burning activities in altered and native forest locations in the Northern Amazon Rainforest, Brazil. We evaluated soils during different climatic periods (dry and rainy) collected at selected sites for pasture, conventional agriculture, and forestry. Intensive conversion to pasture and conventional plantations seriously impacted the bacterial diversities and species richness. The forest area presented the greatest bacterial diversities and species richness, followed by the pasture areas, especially in the 0-5 cm soil layer. Conventional plantations showed the lowest diversities and species richness. There was no change in species richness between the dry and rainy periods; however, the wet period showed lesser species diversities. Based on the analyses, the bacterial communities comprised of the phyla: Acidobacteria, Firmicutes, Verrucomicrobia, Actinobacteria, Proteobacteria, Planctomycetes, and Cyanobacteria. Bacteria trends identified are being considered in future management decisions to preserve biodiversities and the region's forest ecosystems' functioning.

Automated summary

Research in the Amazon rainforest shows that intensive conversion to pasture and conventional plantations has a significant impact on bacterial diversities and species richness, while forest areas exhibit the highest levels of bacterial diversity and species richness. Additionally, the analyses suggest that bacterial communities are composed of several phyla and these trends are being considered in future management decisions to preserve biodiversity and ecosystem functioning.