Rhizosphere microbial communities are plant-host specific, which is theorised to result from physiological differences in growth and competition strategies which influence a hosts root morphology, exudation of metabolites and additional physiological properties. Short-read IlluminaTM sequencing of rhizosphere samples from Eucalyptus and Acacia trees found in a co-occurring and regenerating forest revealed distinct compositional differences in the microbial communities of the host-tree species. Known functions of these microbial communities enhance resource availability for, and physiological status of the plant-host. While 78-84% of fungal genera are shared, their relative abundances differ significantly between hosts. For example, Ectomycorrhizal fungi show distinct host preferences, with specific genera migrating towards or away from each host's rhizosphere. These specialized microbial associations support distinct ecosystem functions, particularly regarding organic decomposition and nitrogen and phosphorous cycling pathways, ultimately facilitating the stable coexistence of these dominant tree genera. As soil microbial communities inhabiting the rhizosphere play a key role in the ecosystem function of their host-species, this research shows that the host-plant specificity of the associating microbial communities mirrors the ecological function of the plant-host, thereby encouraging neighbourhood effects, community dynamics and competition. This molecular approach, combined with functional annotation highlights mutualistic benefits relating to the resilience of trees to stress events (heat, drought, invasion, infection, or fire) to be identified and, where possible, used as a bioindicator for environmental health.
Whilst significant advances in high-throughput sequencing has enabled a deeper characterisation of ecological processes, extrapolation of findings requires restraint. Whilst the annotation of function suggests a way in which the biosphere-lithosphere interface can be characterised at a much higher level of specificity, significant gaps remain in our understanding of the complexity of below ground processes. This talk highlights the key areas in which knowledge and capabilities can be strengthened to achieve a greater understanding of ecosystem functionality in the face of rapid environmental change. This includes challenges facing researchers during DNA extraction, sequencing, bioinformatics and functional annotation.