Intensively managed cellulosic bioenergy feedstock production has high potential in the southern United States. Cellulosic bioenergy feedstock systems could have added sustainability benefits of increased soil carbon storage, yet past work has not focused on the important belowground processes the underlie carbon dynamics in these systems. Plant-microbe interactions and belowground microbiomes play critical roles in plant nutrient acquisition, plant health and performance, and ecosystem function. In particular, microbes are essential to carbon cycling processes such as the decomposition of above- and belowground litter inputs. Yet, most existing knowledge rely on one-time sampling of microbiomes, and little is known about how the complex plant inputs, microbiome assembly, and decomposition feedback loop changes throughout stand development. In addition, alternative silvicultural techniques that accelerate stand development could have large impacts on carbon dynamics via changes in input rates and host-microbe associations. In this collaboration with Dr. Doug Aubrey, we have conducted detailed time-series sampling to investigate belowground microbiome assembly in the first year of stand establishment in two economically important tree species, loblolly pine (Pinus taeda) and sweetgum (Liquidambar styraciflua). Additional proposed experiments (in figure) could uncover the effects of above- and belowground plant carbon inputs on microbiome assembly and its consequences for decomposition and CO2 efflux, but are as yet unfunded.