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Background Frequent fire characterises Australia’s tropical savannas and strongly influences vegetation structure and carbon (C) stocks. Fire management is widely used to reduce greenhouse gas emissions, but long-term effects of fire timing and frequency on woody C accumulation remain uncertain. Aims To quantify stand-level woody C stocks and assess cumulative multi-decadal effects of fire timing and frequency in northern Australian savannas. Methods Field measurements and historical biomass and basal area data from three long-term (17–30-year) fire trials were analysed. Treatments included unburnt controls and burned plots with up to four fire frequencies within a 6-year range and two fire seasons (early and late dry season). Carbon stocks were quantified for standing biomass, coarse woody debris and litter. Key results Total woody C accumulation was greater under early dry season fire than late dry season fire regimes. Longer between-fire intervals (particularly late dry season) may increase woody C stocks, although effect sizes were uncertain. Conclusions Early dry season burning was associated with greater long-term woody C accumulation than late dry season burning. Implications are that early dry season fire management remains important for reducing savanna fire emissions, but optimal fire regimes should consider site-specific conditions and broader ecological objectives.
Ng et al. (Tue,) studied this question.