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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 D 0:82, RMSED7.35 tC ha)
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 tC ha) and lowest in plots burnt late in the dry season
on a biennial basis (42% and 18.2 t Cha). 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.
