HR: 1330h
AN: NB33L-01    [Abstracts]
TI: Ancient Soils in a Sunburnt Country: Nutrient and Carbon Distributions in an Australian Dryland River System
AU: * McIntyre, R E
EM: mcintr01@tartarus.uwa.edu.au
AF: University of Western Australia, 35 Stirling Highway (M090), Crawley, WA 6009 Australia
AU: Grierson, P F
EM: pfgblue@cyllene.uwa.edu.au
AF: University of Western Australia, 35 Stirling Highway (M090), Crawley, WA 6009 Australia
AU: Adams, M A
EM: adamsma@cyllene.uwa.edu.au
AF: University of Western Australia, 35 Stirling Highway (M090), Crawley, WA 6009 Australia
AB: Riparian systems are hotspots in dryland landscapes for nutrient supply and transformation. Biogeochemical fluxes in riparian systems are closely coupled to hydrological flowpaths, which, in dryland regions, are characterised by catastrophic flooding and long periods of erratic or no flow. Re-wetting of soils stimulates soil microbial processes that drive mineralization of nutrients necessary for plant growth. We present here the first data of a 3-year research project investigating biogeochemical processes in riparian systems in the semi-arid Pilbara region of Western Australia. Spatial patterns of nitrogen, phosphorus and carbon were closely related to topographic zone (across floodplain and channels) and vegetation type. NO₃^- and PC_i concentrations were four-fold higher in channel, bank and riparian soils than in soils of floodplain and riparian-floodplain transition zones. Nitrogen distribution was highly heterogeneous in riparian soils (NO₃^- CV=102%, NH₄⁺ CV=84%) while phosphorus was particularly heterogeneous in floodplain soils (PC_i CV=153%, PC_o CV=266%), in comparison to other zones. Phospholipid fatty acid (PLFA) and enzymatic profiles will be used to assess microbial functional groups, combined with mineralisation experiments and stable isotope studies (¹⁵N and ¹³C). These data will improve understanding of biogeochemical cycling in dryland riparian systems, and contribute to improved regional management of water resources.
DE: 0400 Biogeosciences
DE: 1821 Floods
DE: 9330 Australia
DE: 9901 NABS Student Award - Basic Research
DE: 9903 NABS Student Award Methodology
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly