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Productivity and evapotranspiration of two contrasting semiarid ecosystems following the 2011 global carbon land sink anomaly

Cleverly, James; Eamus, Derek; van Gorsel, Eva; Chen, Chao; Rumman, Rizwana; Luo, Qunying; Restrepo-Coupe, Natalia; Li, Longhui; Kljun, Natascha LU and Faux, Ralph, et al. (2016) In Agricultural and Forest Meteorology 220. p.151-159
Abstract
Global carbon balances are increasingly affected by large fluctuations in productivity occurring throughout semiarid regions. Recent analyses found a large C uptake anomaly in 2011 in arid and semiarid regions of the southern hemisphere. Consequently, we compared C and water fluxes of two distinct woody ecosystems (a Mulga (Acacia) woodland and a Corymbia savanna) between August 2012 and August 2014 in semiarid central Australia, demonstrating that the 2011 anomaly was short-lived in both ecosystems. The Mulga woodland was approximately C neutral but with periods of significant uptake within both years. The extreme drought tolerance of Acacia is presumed to have contributed to this. By contrast, the Corymbia savanna was a very large net C... (More)
Global carbon balances are increasingly affected by large fluctuations in productivity occurring throughout semiarid regions. Recent analyses found a large C uptake anomaly in 2011 in arid and semiarid regions of the southern hemisphere. Consequently, we compared C and water fluxes of two distinct woody ecosystems (a Mulga (Acacia) woodland and a Corymbia savanna) between August 2012 and August 2014 in semiarid central Australia, demonstrating that the 2011 anomaly was short-lived in both ecosystems. The Mulga woodland was approximately C neutral but with periods of significant uptake within both years. The extreme drought tolerance of Acacia is presumed to have contributed to this. By contrast, the Corymbia savanna was a very large net C source (130 and 200 g C m−2 yr−1 in average and below average rainfall years, respectively), which is likely to have been a consequence of the degradation of standing, senescent biomass that was a legacy of high productivity during the 2011 anomaly. The magnitude and temporal patterns in ecosystem water-use efficiencies (WUE), derived from eddy covariance data, differed across the two sites, which may reflect differences in the relative contributions of respiration to net C fluxes across the two ecosystems. In contrast, differences in leaf-scale measures of WUE, derived from 13C stable isotope analyses, were apparent at small spatial scales and may reflect the different rooting strategies of Corymbia and Acacia trees within the Corymbia savanna. Restrictions on root growth and infiltration by a siliceous hardpan located below Acacia, whether in the Mulga woodland or in small Mulga patches of the Corymbia savanna, impedes drainage of water to depth, thereby producing a reservoir for soil moisture storage under Acacia while acting as a barrier to access of groundwater by Corymbia trees in Mulga patches, but not in the open Corymbia savanna. (Less)
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subject
keywords
Corymbia savanna, Acacia woodland, Evapotranspiration, Net ecosystem productivity, Water-use efficiency, Global 2011 land sink anomaly
in
Agricultural and Forest Meteorology
volume
220
pages
8 pages
publisher
Elsevier
external identifiers
  • scopus:84955580067
ISSN
1873-2240
DOI
10.1016/j.agrformet.2016.01.086
language
English
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no
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425a9363-dccf-4f6e-a978-90a81a3aefdc
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2018-06-12 12:32:53
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2018-08-26 05:04:10
@article{425a9363-dccf-4f6e-a978-90a81a3aefdc,
  abstract     = {Global carbon balances are increasingly affected by large fluctuations in productivity occurring throughout semiarid regions. Recent analyses found a large C uptake anomaly in 2011 in arid and semiarid regions of the southern hemisphere. Consequently, we compared C and water fluxes of two distinct woody ecosystems (a Mulga (Acacia) woodland and a Corymbia savanna) between August 2012 and August 2014 in semiarid central Australia, demonstrating that the 2011 anomaly was short-lived in both ecosystems. The Mulga woodland was approximately C neutral but with periods of significant uptake within both years. The extreme drought tolerance of Acacia is presumed to have contributed to this. By contrast, the Corymbia savanna was a very large net C source (130 and 200 g C m−2 yr−1 in average and below average rainfall years, respectively), which is likely to have been a consequence of the degradation of standing, senescent biomass that was a legacy of high productivity during the 2011 anomaly. The magnitude and temporal patterns in ecosystem water-use efficiencies (WUE), derived from eddy covariance data, differed across the two sites, which may reflect differences in the relative contributions of respiration to net C fluxes across the two ecosystems. In contrast, differences in leaf-scale measures of WUE, derived from 13C stable isotope analyses, were apparent at small spatial scales and may reflect the different rooting strategies of Corymbia and Acacia trees within the Corymbia savanna. Restrictions on root growth and infiltration by a siliceous hardpan located below Acacia, whether in the Mulga woodland or in small Mulga patches of the Corymbia savanna, impedes drainage of water to depth, thereby producing a reservoir for soil moisture storage under Acacia while acting as a barrier to access of groundwater by Corymbia trees in Mulga patches, but not in the open Corymbia savanna.},
  author       = {Cleverly, James and Eamus, Derek and van Gorsel, Eva and Chen, Chao and Rumman, Rizwana and Luo, Qunying and Restrepo-Coupe, Natalia and Li, Longhui and Kljun, Natascha and Faux, Ralph and Yu, Qiang and Huete, Alfredo},
  issn         = {1873-2240},
  keyword      = {Corymbia savanna,Acacia woodland,Evapotranspiration,Net ecosystem productivity,Water-use efficiency,Global 2011 land sink anomaly},
  language     = {eng},
  month        = {04},
  pages        = {151--159},
  publisher    = {Elsevier},
  series       = {Agricultural and Forest Meteorology},
  title        = {Productivity and evapotranspiration of two contrasting semiarid ecosystems following the 2011 global carbon land sink anomaly},
  url          = {http://dx.doi.org/10.1016/j.agrformet.2016.01.086},
  volume       = {220},
  year         = {2016},
}