Identifying mechanisms for successful ecological restoration with salvaged topsoil in coastal sage scrub communities

Although above-ground metrics remain the standard, restoring functional
ecosystems should promote both above- and belowground biotic communities.
Restoration using salvaged soil — removal and translocation of topsoil
from areas planned for development, with subsequent deposition at degraded
sites — is an alternative to traditional methods. Salvaged soil contains
both seed and spore banks, which may holistically augment restoration.
Salvaged soil methods may reduce non-native germination by burying
non-native seeds, increase native diversity by adding native seeds, or
transfer soil microbiomes, including AMF, to recipient sites. We
transferred soil to three degraded recipient sites and monitored soil
microbes using flow cytometry and molecular analyses, and characterized
the plant community composition. Our findings suggest that salvaged soil
at depths 5 cm reduced non-native grass cover and increased
native plant density and species richness. Bacterial abundance at
recipient sites was statistically equivalent to donor sites abundance.
Overall, topsoil additions affected AMF alpha diversity and community
composition, and increased rhizophilic AMF richness. Because salvaged soil
restoration combines multiple soil components, including native plant and
microbial propagules, it may promote both above- and below-ground
qualities of the donor site, when applying this method for restoring
invaded and degraded ecosystems.