Climatic origin dictates soil microbial responses to short-term experimental drought

Climate models predict widespread precipitation changes across Europe, including more frequent and severe droughts. Drought events can alter soil microbial communities, leading to alterations in soil functioning and further ecosystem services. While long-term drought effects are well studied, short-term droughts during the growing season remain largely unexplored in agricultural soils. Thus, we investigated the microbial responses to short-term experimental drought in agricultural soils in two climatically contrasting European regions: Spain and Sweden. Although soil water content followed a similar drying pattern across both regions, overall microbial respiration and biomass remained stable. Further, arbuscular mycorrhizal fungi biomass revealed opposite regional trends under drought. Using metatranscriptomics we further explored how short-term drought impacted the expression of genes involved in the soil organic matter degradation – a key process in global carbon cycling. Microbial communities in Spanish soils exhibited high functional resistance, indicating historical adaptation to dry conditions. In contrast, drought in Sweden upregulated genes coding for enzymes that degrade complex carbohydrates. Our findings demonstrate that historically wet regions like Sweden may be far more vulnerable to changing precipitation than semi-arid regions like Spain. Additionally, this study highlights how analyzing transcriptional shifts helps us better understand how drought alters agricultural microbial communities and how it may shape ecosystem processes in the face of ongoing climate change.