CRC for Greenhouse Accounting

Research Programs

Project A.1

Belowground carbon dynamics

Project Leader: Dr Roger M Gifford, CSIRO Plant Industry

Objectives:

To improve methodology for quantifying inputs of plant carbon to below-ground carbon pools.
To evaluate the determinants and processes underlying the carbon turnover rates in surface litter, woody debris, fine roots and soil carbon pools.
To quantify the impact of land management practices, land use change, atmospheric composition, and climate change & variability on soil carbon inputs, stocks and fluxes.
To provide inputs into and interactions with CRC-groups studying aboveground biomass, direct effects of atmospheric composition and climate change, and
modelling for improvement in estimates of terrestrial carbon stocks and fluxes.

Strategy:

On the time-scale of current political concern for modifying net fluxes of CO₂ to the atmosphere, the faster turnover pools are the most important because they can be accumulated faster than slow pools and are also more at risk of oxidation to CO₂ if not managed to be conserved. Hence the faster pools and the inputs to these pools, by fine root and litter turnover, are to receive more attention than the slower pools. However, to model the whole system, all pools must be understood better including the mechanisms of stabilisation of soil organic matter in the creation of the slower-turnover pools.

Relevance:

Soil organic C is a major part of the ecosystem C-stock containing about twice as much C as above ground in forests and many-fold as much C as above ground in crops and pastures. The NCAS seeks to estimate soil C dynamics via modelling litter inputs and (GENDEC) and the turn-over in soil C pools (RothC). There is much to be learnt about the processes involved in both those aspects under various environmental and management changes but it has been recognised that the biggest data deficiency of all is the rate of fine root input into the soil pools

Outputs:

Provide a process based account of below ground C allocation and turnover.
Quantify the influence of land management options on the cycling of below- ground carbon for reducing C emissions from below ground.
Define the soil and environmental conditions under which carbon can potentially be sequestered and natural resources sustainably managed.
Provide scientific input (data and equations) that can be used by others to model flows of below- ground carbon at landscape and continental scales.
Build on our established expertise and provide independent science advice on below- ground C stocks and fluxes.

Outcomes

Improved soil C models based on a sound process understanding from Australian soils and management practices

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