Using Inga punctata in forest restoration influences the accumulation of tree soil carbon and nitrogen, and the nitrogen-fixer and lignin degrader bacterial community compositions, complexity and stability.

Abstract AimsThis study was designed to determine if planting the leguminous tree Inga punctata in cleared former tropical premontane wet forest lands changed the Nitrogen (N)-fixer and Lignin Degrader bacterial community compositions, complexity and stability, to enhance the soil carbon (C) and nitrogen (N) components.MethodsSoils were collected from old growth, 4, 8 and 11-year-old I. punctata trees, and assessed for differences in various soil C and N metrics, and the mean of percent sequences (MPS, as “relative abundance” via Next Generation eDNA Sequencing), composition, stability and complexity of the community of N-fixer and Lignin Degrader genera.ResultsThe MPS N-fixer genera decreased and that of the Lignin Degraders increased over time, as did the composition and stability of both groups. There were negative correlations between the MPS levels of the N-fixer and Lignin Degrader genera, positive correlations between the MPS levels of Lignin Degraders, TN, NO3−, TOC, and Biomass C, negative correlations between the MPS levels of Lignin Degraders and NH4+, and opposite correlations between these C and N metrics and MPS levels of N-fixers.ConclusionsThis is the first evidence that I. punctata facilitates changes over time in the amount and composition of tree soil N-fixer and Lignin Degrader genera, enhances the stability and complexity of both groups, increases the accumulation of tree soil C and N, thus, increasing the potential for these soils to serve as C and N sinks, and supporting the future use of this reforestation management strategy.