PhD Scholar
Biologically mediated weathering in the rhizosphere of Australian forest soils
E-mail: david.little@anu.edu.au

Soils and regolith are particularly interesting because of commonly observed emergent patterns that develop over time in response to climate, geology, topography and biological activity. Traditionally, biota-soil interrelationships have been ignored or over-simplified, and few studies have examined the impact of trees on soils in the rhizosphere. Recognition of the importance of rhizosphere processes and recent rapid technological advancement have opened up many avenues for biogeochemical investigation in the rhizosphere.

My research examines roles of low molecular weight organic acid root exudates in providing an essential component of microbial habitat, as well as in mobilising soil metals by such processes as ligand exchange and adsorption to soil minerals. Detailed chemical, mineralogical and microbiological investigations were undertaken using rhizosphere and non-rhizosphere soils under co-occurring Eucalyptus mannifera and Acacia falciformis in a dry sclerophyll forest at Mulloon Creek, Bungendore (NSW).

This research contributes to the scientific understanding of organic acid mineral and organic acid soil microbial community interactions in a forest soil rhizosphere, and has specific implications for understanding:

• biogeochemical cycling and biological weathering in Australian forest soils,
• landscape function, aiding vegetation rehabilitation and bioremediation strategies on degraded or contaminated lands, and
• geochemical exploration, by providing information on how metals move through the rhizosphere to the root, and then how these elements are expressed in the above ground biomass.