Dynamics of standing dead wood and severe fire in north Australian savannas: implications for carbon management
Peter J. Whitehead A B , Brett P. Murphy C , Jay Evans A , Dominique Lynch D , Cameron P. Yates A * , Andrew Edwards A , Harry Mcdermott A and Jeremy Russell-Smith A BA
B
C
D
Abstract
Many fires in north Australian savannas are severe enough to cause canopy scorch, tree death and removal of stags. Better fire management may increase carbon sequestration in trees, perhaps including stags.
To describe and analyse dynamics of stags in tropical savannas (600–1000 mm annual rainfall) in relation to fire and better understand their role in biomass sequestration.
We monitored marked populations of live and dead trees over 12 years. Statistical models describing influences on stag creation and loss are applied in stag dynamics simulations.
Immediately following severe fire, stag biomass increases acutely because many more live trees are killed than stags removed. Between severe fires, stag losses exceed tree deaths, so peaks are quite short. Many ‘new’ stags are lost (fallen or consumed) quickly.
Between fires, stags comprise ~7.5–8.9% of standing above-ground biomass, more under dry conditions and during recovery from severe fire or other drivers of increased tree mortality. Fire management is unlikely to increase proportions of total woody biomass in stags unless it also reduces live biomass.
Reducing frequency of severe fires can increase total carbon sequestration in dry tropical savannas. Prediction uncertainties and management risks around sequestration present daunting challenges for policy-makers and fire management practitioners.
Keywords: biomass, carbon accounting, carbon sequestration, dead wood, fire severity, fire management, savannas, stags, tree mortality.
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