Soil microbial composition and physicochemical data for Southwestern U.S. dryland sites

Escalating soil degradation and ecosystem service losses across global
drylands highlight a clear need for strategic approaches for active
restoration. There is growing interest in using soil microbe inoculation
or “soil transplants'' from intact reference sites to promote
dryland restoration success. Yet, use of soil inoculation treatments is
often not guided by a preliminary understanding of soil community
structure and what organisms and/or functions are lacking in degraded
communities. This study explores how the composition and diversity of
microbial communities differ among degraded, revegetated, and intact
dryland sites. We collected soil samples from degraded, revegetated, and
intact plots at seven different dryland sites across the southwestern
United States, sequenced the 16S and ITS rRNA gene regions from extracted
DNA for bacteria/archaeal and fungal communities respectively, and
analyzed differences in microbial community composition among plots. We
found relatively small, but significant differences in soil microbial
communities between degraded and intact sites. However, we found no
differences in microbial communities between degraded and revegetated
sites, suggesting degraded sites may require active interventions beyond
revegetation, such as direct microbial inoculation, to replenish soil
microbial communities. Several indicator species of intact sites were
identified, including species belonging to groups of biocrust-associated
bacteria and dark septate endophytic fungi, which may be good targets for
inoculation treatments. These findings advance our understanding of how
degradation and revegetation may affect microbial communities and suggest
several microbial taxa that may be useful for inoculation, which could
have actionable implications, and thus improve outcomes, in dryland
restoration.