Can repeated drought change how grassland soil functions during drought?

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Climate change is altering the frequency and severity of drought events. Recent evidence suggests that drought can leave legacy effects on soil microbial communities, but it has been unclear whether past droughts create ecological memory—the capacity of past events to influence current ecosystem response trajectories.

Researchers used a long-term field experiment in a mountain grassland in central Austria, comparing 10 years of recurrent drought events with a single drought event and ambient conditions. Recurrent droughts made microbial communities more dissimilar than those under control conditions or a single drought event and enhanced soil multifunctionality during drought. The researchers calculated multifunctionality using measurements of potential enzymatic activities, soil nutrients, microbial biomass stoichiometry and belowground net primary productivity.

The results indicate that soil microbial community composition changes in concert with its functioning, with consequences for soil processes. The formation of ecological memory in soil under recurrent drought may enhance the resilience of ecosystem functioning against future drought events.