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Land use change and the impact on greenhouse gas exchange in north Australian savanna soils

Grover, S. P. P., Livesley, S. J., Hutley, L. B., Jamali, H., Fest, B., Beringer, J., Butterbach-Bahl, K. and Arndt, S. K. (2012). Land use change and the impact on greenhouse gas exchange in north Australian savanna soils. Biogeosciences,9(1):423-437.

Document type: Journal Article
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Title Land use change and the impact on greenhouse gas exchange in north Australian savanna soils
Author Grover, S. P. P.
Livesley, S. J.
Hutley, L. B.
Jamali, H.
Fest, B.
Beringer, J.
Butterbach-Bahl, K.
Arndt, S. K.
Journal Name Biogeosciences
Publication Date 2012
Volume Number 9
Issue Number 1
ISSN 1726-4170   (check CDU catalogue open catalogue search in new window)
Start Page 423
End Page 437
Total Pages 15
Place of Publication Germany
Publisher Copernicus Publications
Abstract Savanna ecosystems are subjected to accelerating land use change as human demand for food and forest products increases. Land use change has been shown to both increase and decrease greenhouse gas fluxes from savannas and considerable uncertainty exists about the non-CO2 fluxes from the soil. We measured methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) over a complete wetdry seasonal cycle at three replicate sites of each of three land uses: savanna, young pasture and old pasture (converted from savanna 5–7 and 25–30 yr ago, respectively) in the Douglas Daly region of Northern Australia. The effect of break of season rains at the end of the dry season was investigated with two irrigation experiments. Land use change from savanna to pasture increased net greenhouse gas fluxes from the soil. Pasture sites were a weaker sink for CH4 than savanna sites and, under wet conditions, old pastures turned from being sinks to a significant source of CH4. Nitrous oxide emissions were generally very low, in the range of 0 to 5 μg N2O-Nm−2 h−1, and under dry conditions soil uptake of N2O was apparent. Break of season rains produced a small, short lived pulse of N2O up to 20 μgN2O-Nm−2 h−1, most evident in pasture soil. Annual cumulative soil CO2 fluxes increased after clearing,
with savanna (14.6 tCO2-C ha−1 yr−1) having the lowest fluxes compared to old pasture (18.5 tCO2-C ha−1 yr−1) and young pasture (20.0 tCO2-C ha−1 yr−1). Clearing savanna increased soil-based greenhouse gas emissions from 53 to 70 tCO2-equivalents, a 30% increase dominated by an increase in soil CO2 emissions and shift from soil CH4 sink to source. Seasonal variation was clearly driven by soil water content, supporting the emerging view that soil water content is a more important driver of soil gas fluxes than soil temperature in tropical ecosystems where temperature varies little among seasons.
Keywords land use change
greenhouse gas exchange
savanna ecosystems
North Australia
DOI http://dx.doi.org/10.5194/bg-9-423-2012   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
Additional Notes This is an Open Access article distributed under the terms of the Creative Commons Attribution License 3.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Description for Link Link to CC Attribution 3.0 License
URL https://creativecommons.org/licenses/by/3.0/au/legalcode


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Created: Mon, 15 Oct 2012, 12:22:06 CST by Teresa Haendel