Where does all the carbon go? Determining the carbon pool turnover rates in semi-arid biomes of Australia.

Aims

The semi-arid ecosystems of Australia have been recognised a global carbon sink anomaly, accounting for almost 60% of global carbon uptake during consecutive seasons of high rainfall arising from La Niña events. This raises the questions of where this carbon is going, and whether it is stable enough to be considered a significant terrestrial carbon pool?

The rivers of Queensland’s Channel Country lose large volumes of discharge on its journey to Lake Eyre. Once a decade rainfall events are sufficient to overcome these losses and the floodwaters fill Lake Eyre to typical levels. When this happens, the desert is transformed into a temporary green oasis. The impact of these events on the longer-term carbon budget is not well understood. This project will incorporate a time series analysis of long-term satellite data archives with targeted field surveys, to quantify the significance of these greening events. By making use of long-term satellite archives of vegetation indices, this project will address the following questions:

• How spatially extensive is this greening and how long lived?

• How do amount and spatiotemporal distribution of rainfall control the hydrology of the flood wave and consequent greening in these remote (and poorly gauged) fluvial systems?

• Can we link the flood event record to the longer-term sediment record using sediment cores from the key drainage basins and Lake Eyre?

• What is the impact of the above on the soil carbon pool, and how resistant is it to decomposition?

Methods

This project includes a significant field component to understand the relationship between satellite estimates of riparian vegetation (including both vascular plants and microphyte soil components), net primary productivity, and catchment hydrology. Field collection of soil carbon samples will be undertaken at key sequestration locations, and topographic profiles collected in natural ‘gauge’ locations along both the Cooper and Diamantina rivers. Key analytical components of the project will include phyolith analysis, as well as the utilisation of programmes R and Python, for which training will be provided.

Applicants

Applicants are encouraged from a variety of disciplinary backgrounds including Geography, Environmental and Atmospheric science. They should have a 2.1 degree and ideally have undertaken an MS in a subject relevant to this project. Applicants should be prepared to undertake fieldwork in challenging and remote desert areas. While remaining with its scope applicants are invited to shape a proposal to meet their own interests and expertise.