This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2025. The fellowship supports research and training of the fellow that will contribute to biology in innovative ways. Interactions between plants and soil microbes can feedback to affect the next plant generation. This research project will examine how both beneficial and antagonistic soil microbiota near dead trees influences the assembly and biodiversity of the next tree generation. Using northern temperate forests as a model system, this research will experimentally test the biotic soil environment as a mechanism of successional replacement in forests. Tree mortality is accelerating across many forest types, creating new opportunities for forest regeneration, and results from this project can be used to improve predictions of future forest composition. During the project, the fellow will contribute to society through student mentoring, workshop development, and management extension. Biological systems are shaped by both living organisms and the environmental legacies of organisms that were previous inhabitants. This research focuses on the temporal dynamics of soilborne microbiota associated with dead trees (hereafter soil legacies). Negative feedback between plants and soil microbes can maintain diversity within and among plant species, but how these interactions change across multiple host-generations remains unknown. Through a reciprocal transplant experiment, microbial metabarcoding, and m