Summer bushfires near densely-populated areas in southern
Australia attract
the most public attention, but the continent’s largest and most frequent fires
actually occur in the spring in the tropical savannas of northern Australia.
NASA’s Aqua satellite
captured this natural-color image of wildfires burning on Cape York Peninsula,
the northernmost part of Australia. Smoke plumes from multiple fires are
visible streaming west; red outlines indicate hot spots where MODIS detected
unusually warm surface temperatures associated with fires.
Three main meteorological variables affect fire behavior:
atmospheric humidity, air temperature, and wind strength. On Cape York
Peninsula, humidity drops and temperatures rise beginning with the arrival of
the dry season in March. By the end of November, grasses and woodland trees in
the region have reached their most flammable state. In this case, steady winds
(about 20 kilometers/12 miles per hour) have helped sustain fires that were
likely started by lightning and human activity.
About half of the savanna woodlands on Cape York Peninsula burn
either every year or so, typically late in the dry season. Dried grasses, which
receive ample sunshine and rain during the wet season, provide the bulk of the
fuel. As the dry season progresses, trees also drop loads of leaves and twigs
that help fuel fires. Key grasses and trees in the region include Sorghum, Eucalyptus, and
Corymbia.
Despite the frequency of the burning, wildfires on Cape York
Peninsula are generally less severe than in southern Australia because fungi,
bacteria, and other decomposers that thrive in the region
continuously break dried grass and leaf litter down. Fewer decomposers live in
southern Australia, making it possible for leaf litter and other fuel to build
up for decades and prime the landscape for extremely destructive fires.
· References
1.
Further Reading
3.
Crowley, G.M.
(2008, Oct. 9). Changing
fire management in the pastoral lands of Cape York Peninsula of northeast
Australia. Geographical
Research.
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