<b>50-year fire legacy regulates soil microbial carbon and nutrient cycling responses to new fire</b>

Fire disturbances are becoming more common, more intense, and further-reaching across the globe, with consequences for the functioning of affected ecosystems. Importantly, fire can have strong effects on the soil microbiome, including community and functional changes after fire, but surprisingly little is known regarding the role of soil fire legacy in shaping responses to recent fire. To address this gap, we conducted a manipulative field experiment administering fire across 32 soils with varying fire legacies, including combinations of 1-7 historic fires and 1-33 years since most recent fire. We analyzed soil metatranscriptomes, determining for the first time how recent fire and fire legacy interactively affect metabolically-active soil microbial taxa, the microbial regulation of important carbon (C), nitrogen (N) and phosphorus (P) cycling, expression of carbohydrate-cycling enzyme pathways, and functional gene co-expression networks.