Shifts on archaeal community structure in pure and mixed Eucalyptus grandis and Acacia mangium plantations

Abstract

Abstract Archaeal community has important contributors to nutrient cycling in the forest ecosystems. However, how soil-litter attributes shift their community structure remains poorly understood. To date, the structure of the archaeal community has never been reported either in pure or in mixed eucalypt and acacia plantations, especially in tropical soils. Here, we analyzed the archaeal community and performed correlations with C, N and P attributes in soil-litter layers of pure Eucalyptus grandis without (E) and with N fertilization (E\xa0+\xa0N), a mixed system of E. grandis and Acacia mangium (E\xa0+\xa0A), and a pure A. mangium (A) plantation. We extracted DNA from soil (0–20\xa0cm) and litter samples at 27 and 39\xa0months after planting and sequenced the archaeal 16S rRNA gene. We also analyzed the abundance of 16S rRNA and amoA genes by quantitative PCR and assessed the correlations between molecular data with soil-litter attributes (i.e., microbial and enzyme activities, and C, N and P contents). The high-throughput sequencing of the archaeal 16S rRNA gene revealed that the treatments influenced the archaeal community structure. However, the litter layer showed more significant modifications, since archaeal richness, diversity, and the relative abundance of Thaumarchaeota increased in the litter of pure acacia and mixed treatments at both, 27 and 39\xa0months after planting. There was no clear pattern regarding the abundance of functional genes in the soil, but archaeal structure responded to treatments in the litter layer, in which NH4+, total-N and the C/N ratio were the most important attributes for community group differentiation. Our study provides novel insights into the structure and function of archaea in pure and mixed forest systems, but highlights that young mixed plantations exert a low effect on soil community structure. Archaeal community may have an important role in nutrient cycling in the litter interface, especially related to the N cycle in the initial stages of tree development.