sustainability Article Influence of Acacia mangium on Soil Fertility and Bacterial Community in Eucalyptus Plantations in the Congolese Coastal Plains Lydie-Stella Koutika 1,2,* , Alessia Fiore 2, Silvia Tabacchioni 2, Giuseppe Aprea 2, Arthur Prudêncio de Araujo Pereira 3 and Annamaria Bevivino 2,* 1 Research Center on the Durability and the Productivity of Industrial Plantations (CRDPI), Av. Ma Loango Moe Poaty, Pointe-Noire BP 1291, Republic of the Congo 2 Department for Sustainability, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, ENEA Casaccia Research Centre, 00123 Rome, Italy; alessia.fi
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[email protected] (A.B.); Tel.: +242-06-813-3452 (L.-S.K.); +39-06-3048-3868 (A.B.) Received: 8 September 2020; Accepted: 20 October 2020; Published: 22 October 2020 Abstract: Productivity and sustainability of tropical forest plantations greatly rely on regulation of ecosystem functioning and nutrient cycling, i.e., the link between plant growth, nutrient availability, and the microbial community structure. So far, these interactions have never been evaluated in the Acacia and Eucalyptus forest planted on infertile soils in the Congolese coastal plains. In the present work, the soil bacterial community has been investigated by metabarcoding of the 16S rRNA bacterial gene in different stands of monoculture and mixed-species plantation to evaluate the potential of nitrogen-fixing trees on nutrient and bacterial structure.