Assessing the carbon sequestration potential of mesic savannas in the Northern Territory, Australia: approaches, uncertainties and potential impacts of fire

Robyn Williams, Lindsay Hutley, Garry D Cook, A EDWARDS, X Chen

    Research output: Contribution to journalArticle

    Abstract

    Tropical savannas cover a quarter of the Australian landmass and the biome represents a significant potential carbon sink. However, these savannas are subject to frequent and extensive fire. Fire regimes are likely to affect the productivity and carbon sequestration potential of savannas, through effects on both biomass and carbon emissions. The carbon sequestration potential has been estimated for some savanna sites by quantifying carbon storage in biomass and soil pools, and the fluxes to these pools. Using different techniques, previous work in these savannas has indicated that net ecosystem productivity [NEP, net primary productivity (NPP) less heterotrophic respiration] was about -3 t C ha-1 y-1 (i.e. a carbon sink). However, the impacts of fire were not accounted for in these calculations. Estimates of NEP have been combined with remotely-sensed estimates of area burnt and associated emissions for a an extensive area of mesic savanna in Arnhem Land, NT, Australia. Combining NEP estimates with precise fire data provides an estimate of net biome productivity (NBP), a production index that includes carbon loss through disturbance (fire), and is thus a more realistic indicator of sequestration rate from this biome. This preliminary analysis suggests that NBP is approximately -1 t C ha-1 y-1 (i.e. a carbon sink). A reduction in the annual area burnt is likely to increase the sink size. Uncertainties surrounding these estimates of NBP and the implications of these uncertainties for land management in these extensive landscapes are discussed.
    Original languageEnglish
    Pages (from-to)415-422
    Number of pages8
    JournalFunctional Plant Biology
    Volume31
    Issue number5
    Publication statusPublished - 2004

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