Effect of fire and tree-grass patches on soil nitrogen in Australian tropical savannas

Richards, Anna E., Brackin, Richard, Lindsay, D. Alexander J. and Schmidt, Susanne (2012) Effect of fire and tree-grass patches on soil nitrogen in Australian tropical savannas. Austral Ecology, 37 6: 668-677. doi:10.1111/j.1442-9993.2011.02335.x

Author Richards, Anna E.
Brackin, Richard
Lindsay, D. Alexander J.
Schmidt, Susanne
Title Effect of fire and tree-grass patches on soil nitrogen in Australian tropical savannas
Journal name Austral Ecology   Check publisher's open access policy
ISSN 1442-9985
Publication date 2012-09-01
Year available 2012
Sub-type Article (original research)
DOI 10.1111/j.1442-9993.2011.02335.x
Open Access Status Not yet assessed
Volume 37
Issue 6
Start page 668
End page 677
Total pages 10
Place of publication Richmond, VIC, Australia
Publisher Wiley-Blackwell Publishing Asia
Language eng
Abstract Fire is an important driver of nutrient cycling in savannas. Here, we determined the impact of fire frequency on total and soluble soil nitrogen (N) pools in tropical savanna. The study sites consisted of 1-ha experimental plots near Darwin, Australia, which remained unburnt for at least 14 years or were burnt at 1-, 2- or 5-year intervals over the past 6 years. Soil was analysed from patches underneath tree canopies and in inter-canopy patches at 1, 12, 28, 55 and 152 days after fire. Patch type had a significant effect on all soil N pools, with greater concentrations of total and soluble (nitrate, ammonium, amino acids) N under tree canopies than inter-canopy patches.The ‘time since the last fire’ had no significant effect on N pools. Fire frequency similarly did not affect total soil N but it did influence soluble soil N. Soil amino acids were most prominent in burnt savanna, ammonium was highest in infrequently burnt (5-year interval) savanna and nitrate was highest in unburnt savanna.We suggest that the main effect of fire on soil N relations occurs indirectly through altered tree-grass dynamics. Previous studies have shown that high fire frequencies reduce tree cover by lowering recruitment and increasing mortality. Our findings suggest that these changes in tree cover could result in a 30% reduction in total soil N and 10–60% reductions in soluble N pools. This finding is consistent with studies from savannas globally, providing further evidence for a general theory of patchiness as a key driver of nutrient cycling in the savanna biome.
Keyword Amino acid
Fire frequency
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Agriculture and Food Sciences
Official 2013 Collection
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Citation counts: TR Web of Science Citation Count  Cited 6 times in Thomson Reuters Web of Science Article | Citations
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