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Turning up the heat: The impacts of Andropogon gayanus (gamba grass) invasion on fire behaviour in northern Australian savannas

Setterfield, Samantha A., Rossiter-Rachor, Natalie A., Hutley, Lindsay B., Douglas, Michael M. and Williams, Richard J. (2010). Turning up the heat: The impacts of Andropogon gayanus (gamba grass) invasion on fire behaviour in northern Australian savannas. Diversity and Distributions: a journal of conservation biogeography,16(5):854-861.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 33 times in Scopus Article | Citations
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IRMA ID 81704288xPUB144
Title Turning up the heat: The impacts of Andropogon gayanus (gamba grass) invasion on fire behaviour in northern Australian savannas
Author Setterfield, Samantha A.
Rossiter-Rachor, Natalie A.
Hutley, Lindsay B.
Douglas, Michael M.
Williams, Richard J.
Journal Name Diversity and Distributions: a journal of conservation biogeography
Publication Date 2010
Volume Number 16
Issue Number 5
ISSN 1366-9516   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-77955747185
Start Page 854
End Page 861
Total Pages 8
Place of Publication United Kingdom
Publisher Wiley-Blackwell Publishing Ltd.
Abstract Aim
This study aimed to quantify changes in fire severity resulting from the invasion of Australia’s tropical savannas by the African grass Andropogon gayanus Kunth. (gamba grass).

Location

Mesic savannas of the Northern Territory, Australia.

Method
Byram’s fire-line intensity (If), fuel load and architecture, and two post-fire indicators of fire intensity – scorch height (SH) and char height (CH) of woody vegetation – were determined for fires in native grass savanna and A. gayanus invaded savanna. Leaf scorch is the height at which the fire’s radiant heat browns leaf tissue, and leaf char is the height that radiant heat blackens or consumes leaf tissue and provides an indirect measure of flame height. These data, and 5 years of similar data collected from the Kapalga Fire Project in Kakadu National Park, were used to develop empirical relationships between If and the post-fire indices of fire intensity.

Results
A relationship between A. gayanus If and SH could not be developed because complete canopy scorch occurred in most A. gayanus fires, even at low If. In contrast, A. gayanus If was strongly correlated with CH. This empirical relationship was substantially different from that for native grass fires. For a given If, there was a significantly greater CH in invaded sites. This increase in radiant heat is attributable to the increased biomass (mean 3.6 t ha−1 in native grasses compared to 11.6 t ha−1 in A. gayanus) and height (approximately 0.5 m in native grasses compared to 4 m in A. gayanus) of the standing fine fuel.

Main conclusion
Andropogon gayanus invasion resulted in substantial changes in fire behaviour. This has important regional implications owing to the current (10,000–15,000 km2) and predicted (380,000 km2) area of invasion and the negative consequences for the native savanna biota that has evolved with frequent but relatively low-intensity fire.
DOI http://dx.doi.org/10.1111/j.1472-4642.2010.00688.x   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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