Abstract. Fire regimes across the globe have been altered through changes in land use,
land management, and climate conditions. Understanding how these modified fire
regimes impact vegetation structure and dynamics is essential for informed
biodiversity conservation and carbon management in savanna ecosystems. We
used a fire experiment at the Territory Wildlife Park (TWP), northern
Australia, to investigate the consequences of altered fire regimes for
vertical habitat structure and above-ground carbon storage. We mapped
vegetation three-dimensional (3-D) structure in high spatial resolution with
airborne lidar across 18 replicated 1 ha plots of varying fire frequency
and season treatments. We used lidar-derived canopy height and cover metrics
to extrapolate field-based measures of woody biomass to the full extent of
the experimental site (R2=0.82, RMSE = 7.35 t C ha−1) and
analysed differences in above-ground carbon storage and canopy structure among
treatments. Woody canopy cover and biomass were highest in the absence of
fire (76 % and 39.8 t C ha−1) and lowest in plots burnt late in
the dry season on a biennial basis (42 % and 18.2 t C ha−1).
Woody canopy vertical profiles differed among all six fire treatments, with
the greatest divergence in height classes <5 m. The magnitude of fire effects
on vegetation structure varied along the environmental gradient underpinning
the experiment, with less reduction in biomass in plots with deeper soils.
Our results highlight the large extent to which fire management can shape
woody structural patterns in savanna landscapes, even over time frames as
short as a decade. The structural profile changes shown here, and the
quantification of carbon reduction under late dry season burning, have
important implications for habitat conservation, carbon sequestration, and
emission reduction initiatives in the region.
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