Global meta-analysis shows progress towards recovery of soil microbiota following revegetation

The global declines in biodiversity and ecosystem integrity demand effective restoration. Soil microbiota are fundamentally linked to biodiversity and ecosystem restoration, as they are central to important ecological functions (e.g., nutrient cycling) and are extremely species rich. Their importance, plus the growing affordability of high-throughput sequencing, has resulted in rapid growth of studies that associate soil microbiota recovery and ecosystem restoration via native plant revegetation. Here we provide a systematic literature search and meta-analysis of the association between native plant revegetation and recovery of soil microbiota, identifying 26 datasets. We show that the soil microbial composition in revegetated sites was more similar to reference sites than degraded sites, indicating the recovery of soil microbiota with revegetation. However, a significant difference in composition between revegetated and reference sites indicates that a restoration gap remains. Bacteria showed greater recovery than fungi, which is consistent with bacteria having shorter generation times and being less dispersal-limited than fungi. We observed no general effect of revegetation on soil microbial richness. Showing that soil biodiversity is generally being returned via native plant revegetation should help conservation policymakers and practitioners that utilise this approach be more confident that their efforts are helping to combat global ecological and biodiversity declines. However, more research is required into the drivers of – and solutions to – the restoration gap, such as long-term monitoring of soil microbiota recovery, as this gap may present a long-term legacy that cannot be overcome with current-day revegetation practices.