Carl Watson, Flinders University
Shawn Peddle, Flinders University
Riley Hodgson, Flinders University
Craig Liddicoat, Flinders University
Mike Gardner, Flinders University
Martin Breed, Flinders University

Anthropogenic disturbances continue to degrade vast areas of the planet, contributing to climate change, and driving the global extinction crisis. Ecological restoration – the assisted recovery of degraded ecosystems – has a key role to play in addressing these challenges. Due to being an integral part of all terrestrial ecosystems, soil microbial communities are an important consideration in restoration ecology. The growing affordability of high-throughput marker-gene sequencing has resulted in restoration ecology increasingly using soil microbial communities as an indicator of restoration progress. Here we synthesise the findings of 26 datasets, and show a general trend of revegetation leading to a significant return of the soil microbial community to a reference-like composition. The composition of revegetated sites was more similar to reference (the target community) sites, than to unrestored (negative control) sites, indicating that soil microbial communities are being restored – although a difference between revegetated and reference sites signifies that there is still a restoration gap. Additionally, there was an effect of microbial taxonomic group, with bacterial datasets showing more restoration progress, and fungi showing comparatively little. This divergence could be explained by the different niches that bacteria and fungi occupy during ecosystem development. No overall effect of revegetation on soil microbial community alpha diversity was found, supporting previous findings examining land use change. Our results show that despite restoration occurring in varying ecosystems and climates, and responding to different sources of degradation, the practice of ecological restoration is generally heading in the right direction when it comes to restoring soil microbial communities.