Soil bacterial community differences along a coastal restoration chronosequence

Abstract

Restoration interventions such as revegetation are globally-important to combat biodiversity declines and land degradation. However, restoration projects are generally poorly monitored because current approaches to monitoring are limited in their ability to assess important components of biodiversity, such as belowground microbial diversity. Since soil bacterial communities mediate many belowground ecosystems processes and represent substantial biodiversity in their own right, bacteria are important components to monitor during ecosystem restoration. High-throughput amplicon sequencing (DNA metabarcoding) has been put forward as a potential cost-effective, scalable and easy-to-standardise partial solution to restoration’s monitoring problem. However, its application to restoration projects has to date been limited. Here, we used DNA metabarcoding of bacterial 16S rRNA gene from soil DNA to explore community differences across a 16-year restoration chronosequence. The bacterial composition in the oldest revegetation sites was comparable to the remnant sites. Proteobacteria and Acidobacteria were significantly higher in relative sequence abundance, while Actinobacteria was significantly lower, with time since revegetation. Classes Alphaproteobacteria and Acidobacteria were indicative of remnant and the oldest revegetation sites, while Deltaproteobacteria and Rubrobacteria were characteristic of younger revegetation sites. Changes in the soil physical and chemical characteristics associated with revegetation appear to shape bacterial community structure and composition. These findings provide evidence that revegetation can have positive effects on belowground microbial communities, and help demonstrate that the soil bacterial community can be restored towards its native state by revegetation, which may be useful in restoration monitoring.