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

<p>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.</p>