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Andropogon gayanus (Gamba Grass) Invasion Increases Fire-mediated Nitrogen Losses in the Tropical Savannas of Northern Australia

Rossiter-Rachor, Natalie A., Setterfield, Samantha A., Douglas, Michael M., Hutley, Lindsay B. and Cook, Garry D. (2008). Andropogon gayanus (Gamba Grass) Invasion Increases Fire-mediated Nitrogen Losses in the Tropical Savannas of Northern Australia. Ecosystems,11(1):77-88.

Document type: Journal Article

IRMA ID 81108725xPUB16
Title Andropogon gayanus (Gamba Grass) Invasion Increases Fire-mediated Nitrogen Losses in the Tropical Savannas of Northern Australia
Author Rossiter-Rachor, Natalie A.
Setterfield, Samantha A.
Douglas, Michael M.
Hutley, Lindsay B.
Cook, Garry D.
Journal Name Ecosystems
Publication Date 2008
Volume Number 11
Issue Number 1
ISSN 1435-0629   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-43149114426
Start Page 77
End Page 88
Total Pages 12
Place of Publication Berlin
Publisher Springer
Field of Research 0501 - Ecological Applications
0607 - Plant Biology
HERDC Category C1 - Journal Article (DEST)
Abstract Invasive alien grasses can substantially alter fuel loads and fire regimes which could have significant consequences for fire-mediated nutrient losses. The effects of the alien grass Andropogon gayanus Kunth. (Gamba grass) on fire-mediated nutrient losses was evaluated in Australia’s tropical savannas. Losses of macronutrients during fire were determined by comparing the nutrient pools contained in the fine fuel before fire and in the ash after fire. Pre-fire grass nutrient pools were significantly higher in A. gayanus plots than in native grass plots for all nutrients measured (N, P, K, S, Ca, and Mg). Nutrient losses were substantially higher in A. gayanus plots, with 113% higher losses for N, 80% for P, 56% for K, 63 for S, 355% for Ca, and 345% for Mg. However, only losses of N and Mg varied significantly between grass types. A simplified savanna ecosystem nutrient budget estimated that A. gayanus fires led to the net N loss of 20 kg ha−1 y−1. This is a conservative estimate because total fuel loads were relatively low (7.85 t ha−1) for A. gayanus invaded plots leading to a relatively moderate intensity fire (6,408 kW m−1). Higher A. gayanus fuel loads and fire intensities could potentially lead to losses of up to 61.5 kg N ha−1 from the grass fuel. Over the long term, this is likely to lead to depletion of soil nutrients, particularly N, in the already low-fertility tropical savanna soils.
DOI http://dx.doi.org/10.1007/s10021-007-9108-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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Created: Wed, 29 Apr 2009, 15:00:08 CST by Sarena Wegener