Soil bacterial composition and diversity dynamics in atlantic forest and coffee cultivation in southeastern Brazil

Abstract

Anthropogenic activity in the Atlantic Forest biome in Brazil has been intensified over time, transforming it mainly into cultivation areas and population settlements. Coffee cultivation is an agricultural activity exerted on this biome. However, the implications of this activity on biological diversity are still poorly understood, especially concerning soil bacterial community dynamics. This study aimed to assess how the conversion of natural Atlantic Forest areas to coffee plantations impacts soil bacterial community composition and diversity. For this purpose, soil samples were collected through a transect design in areas of Atlantic Forest and coffee crops, and bacterial communities were assessed by using a metataxonomic approach. Our results showed that the conversion of Atlantic Forest to coffee cultivation promotes soil alpha and gamma bacterial diversity, closely related to increases in soil pH. Coffee plantations are commonly treated with fertilizers and correctives (lime applications), and this last allows a reduction of soil acidity promoting bacterial activity. A greater nutrient availability and a decrease in soil acidity were differentiating factors in soil bacterial composition. In Atlantic Forest areas, soil acidity and Fe drive changes in bacterial composition, and in coffee plantations bacterial composition was associated with a fertility gradient. P availability and texture were also differentiating attributes of soil bacterial structure among land uses. Atlantic Forest had a bacterial composition associated with higher P availability and Clay content and Coffee plantations with a higher Silt content. Conversion of Atlantic Forest to coffee plantations promoted the abundance of some bacterial phyla and a higher Proteobacteria to Acidobacteria ratio. Finally, the variance of the soil bacterial community was mostly explained by soil properties.