WHAT THE EVIDENCE SAYS
Across a 4,000-km field survey, soil conditions and biological groups showed sequential threshold responses to aridity. Plant, bacterial and fungal diversity generally declined beyond their thresholds, while archaeal diversity increased. Salinity became more negatively associated with plants, bacteria and fungi as aridity increased, and plant–bacteria and plant–fungi diversity relationships strengthened in drier sites while plant–archaea relationships decoupled.
WHY IT MATTERS / OUR READ
A single biodiversity metric will miss how dryland systems reorganize. Aboveground plants and different microbial groups can cross different thresholds and even move in opposite directions, so resilience monitoring should couple vegetation with soil conditions and multiple microbial groups where feasible.
CAVEATS / UNCERTAINTY
The study substitutes a broad spatial aridity gradient for temporal change; it therefore identifies field associations and thresholds rather than experimentally proving the trajectory of future aridification. Results may be region- and taxon-specific.
SOURCE
Communications Earth & Environment — primary study
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