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Carbon cycle responses of semi-arid ecosystems to positive asymmetry in rainfall

Haverd, Vanessa; Ahlström, Anders LU ; Smith, Benjamin LU and Canadell, Josep G. (2017) In Global Change Biology 23(2). p.793-800
Abstract
Recent evidence shows that warm semi-arid ecosystems are playing a disproportionate role in the interannual variability and greening trend of the global carbon cycle given their mean lower productivity when compared with other biomes (Ahlström et al. 2015 Science, 348, 895). Using multiple observations (land-atmosphere fluxes, biomass, streamflow and remotely sensed vegetation cover) and two state-of-the-art biospheric models, we show that climate variability and extremes lead to positive or negative responses in the biosphere, depending on vegetation type. We find Australia to be a global hot spot for variability, with semi-arid ecosystems in that country exhibiting increased carbon uptake due to both asymmetry in the interannual... (More)
Recent evidence shows that warm semi-arid ecosystems are playing a disproportionate role in the interannual variability and greening trend of the global carbon cycle given their mean lower productivity when compared with other biomes (Ahlström et al. 2015 Science, 348, 895). Using multiple observations (land-atmosphere fluxes, biomass, streamflow and remotely sensed vegetation cover) and two state-of-the-art biospheric models, we show that climate variability and extremes lead to positive or negative responses in the biosphere, depending on vegetation type. We find Australia to be a global hot spot for variability, with semi-arid ecosystems in that country exhibiting increased carbon uptake due to both asymmetry in the interannual distribution of rainfall (extrinsic forcing), and asymmetry in the response of gross primary production (GPP) to rainfall change (intrinsic response). The latter is attributable to the pulse-response behaviour of the drought-adapted biota of these systems, a response that is estimated to be as much as half of that from the CO2 fertilization effect during 1990–2013. Mesic ecosystems, lacking drought-adapted species, did not show an intrinsic asymmetric response. Our findings suggest that a future more variable climate will induce large but contrasting ecosystem responses, differing among biomes globally, independent of changes in mean precipitation alone. The most significant changes are occurring in the extensive arid and semi-arid regions, and we suggest that the reported increased carbon uptake in response to asymmetric responses might be contributing to the observed greening trends there. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
semi-arid ecosystems rainfall asymmetry greening trend global carbon cycle Australia
in
Global Change Biology
volume
23
issue
2
pages
8 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:84990192180
  • wos:000394343300029
ISSN
1365-2486
DOI
10.1111/gcb.13412
language
English
LU publication?
yes
id
bbe20c0d-58c4-49b3-948e-c14d94e642b7
date added to LUP
2016-12-27 15:52:32
date last changed
2018-05-20 04:30:01
@article{bbe20c0d-58c4-49b3-948e-c14d94e642b7,
  abstract     = {Recent evidence shows that warm semi-arid ecosystems are playing a disproportionate role in the interannual variability and greening trend of the global carbon cycle given their mean lower productivity when compared with other biomes (Ahlström et al. 2015 Science, 348, 895). Using multiple observations (land-atmosphere fluxes, biomass, streamflow and remotely sensed vegetation cover) and two state-of-the-art biospheric models, we show that climate variability and extremes lead to positive or negative responses in the biosphere, depending on vegetation type. We find Australia to be a global hot spot for variability, with semi-arid ecosystems in that country exhibiting increased carbon uptake due to both asymmetry in the interannual distribution of rainfall (extrinsic forcing), and asymmetry in the response of gross primary production (GPP) to rainfall change (intrinsic response). The latter is attributable to the pulse-response behaviour of the drought-adapted biota of these systems, a response that is estimated to be as much as half of that from the CO2 fertilization effect during 1990–2013. Mesic ecosystems, lacking drought-adapted species, did not show an intrinsic asymmetric response. Our findings suggest that a future more variable climate will induce large but contrasting ecosystem responses, differing among biomes globally, independent of changes in mean precipitation alone. The most significant changes are occurring in the extensive arid and semi-arid regions, and we suggest that the reported increased carbon uptake in response to asymmetric responses might be contributing to the observed greening trends there.},
  author       = {Haverd, Vanessa and Ahlström, Anders and Smith, Benjamin and Canadell, Josep G.},
  issn         = {1365-2486},
  keyword      = {semi-arid ecosystems rainfall asymmetry greening trend global carbon cycle Australia},
  language     = {eng},
  number       = {2},
  pages        = {793--800},
  publisher    = {Wiley-Blackwell},
  series       = {Global Change Biology},
  title        = {Carbon cycle responses of semi-arid ecosystems to positive asymmetry in rainfall},
  url          = {http://dx.doi.org/10.1111/gcb.13412},
  volume       = {23},
  year         = {2017},
}