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Plant Traits are Key Determinants in Buffering the Meteorological Sensitivity of Net Carbon Exchanges of Arctic Tundra

López-Blanco, Efrén; Lund, Magnus LU ; Christensen, Torben R. LU ; Tamstorf, Mikkel P.; Smallman, Thomas L.; Slevin, Darren; Westergaard-Nielsen, Andreas; Hansen, Birger U.; Abermann, Jakob and Williams, Mathew (2018) In Journal of Geophysical Research - Biogeosciences
Abstract

The climate sensitivity of carbon (C) cycling in Arctic terrestrial ecosystems is a major unknown in the Earth system. There is a lack of knowledge about the mechanisms that drive the interactions between photosynthesis, respiration, and changes in C stocks across full annual cycles in Arctic tundra. We use a calibrated and validated model (soil-plant-atmosphere; SPA) to estimate net ecosystem exchange (NEE), gross primary production (GPP), ecosystem respiration (Reco), and internal C processing across eight full years. SPA's carbon flux estimates are validated with observational data obtained from the Greenland Ecosystem Monitoring program in West Greenland tundra. Overall, the model explained 73%, 73%, and 50% of the... (More)

The climate sensitivity of carbon (C) cycling in Arctic terrestrial ecosystems is a major unknown in the Earth system. There is a lack of knowledge about the mechanisms that drive the interactions between photosynthesis, respiration, and changes in C stocks across full annual cycles in Arctic tundra. We use a calibrated and validated model (soil-plant-atmosphere; SPA) to estimate net ecosystem exchange (NEE), gross primary production (GPP), ecosystem respiration (Reco), and internal C processing across eight full years. SPA's carbon flux estimates are validated with observational data obtained from the Greenland Ecosystem Monitoring program in West Greenland tundra. Overall, the model explained 73%, 73%, and 50% of the variance in NEE, GPP, and Reco, respectively, and 85% of the plant greenness variation. Flux data highlighted the insensitivity of growing season NEE to interannual meteorological variability, due to compensatory responses of photosynthesis and ecosystem respiration. In this modelling study, we show that this NEE buffering is the case also for full annual cycles. We show through a sensitivity analysis that plant traits related to nitrogen are likely key determinants in the compensatory response, through simulated links to photosynthesis and plant respiration. Interestingly, we found a similar temperature sensitivity of the trait-flux couplings for GPP and Reco, suggesting that plant traits drive the stabilization of NEE. Further, model analysis indicated that wintertime periods decreased the C sink by 60%, mostly driven by litter heterotrophic respiration. This result emphasizes the importance of wintertime periods and allows a more comprehensive understanding of full annual C dynamics.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Arctic tundra, ecosystem exchange, ecosystem respiration, gross primary production, plant traits, process-based modeling
in
Journal of Geophysical Research - Biogeosciences
publisher
American Geophysical Union
external identifiers
  • scopus:85052945068
ISSN
2169-8953
DOI
10.1029/2018JG004386
language
English
LU publication?
yes
id
4c4fb1d8-2185-4767-92ed-f35feaa3ae10
date added to LUP
2018-10-22 16:20:49
date last changed
2019-01-06 14:11:43
@article{4c4fb1d8-2185-4767-92ed-f35feaa3ae10,
  abstract     = {<p>The climate sensitivity of carbon (C) cycling in Arctic terrestrial ecosystems is a major unknown in the Earth system. There is a lack of knowledge about the mechanisms that drive the interactions between photosynthesis, respiration, and changes in C stocks across full annual cycles in Arctic tundra. We use a calibrated and validated model (soil-plant-atmosphere; SPA) to estimate net ecosystem exchange (NEE), gross primary production (GPP), ecosystem respiration (R<sub>eco</sub>), and internal C processing across eight full years. SPA's carbon flux estimates are validated with observational data obtained from the Greenland Ecosystem Monitoring program in West Greenland tundra. Overall, the model explained 73%, 73%, and 50% of the variance in NEE, GPP, and R<sub>eco</sub>, respectively, and 85% of the plant greenness variation. Flux data highlighted the insensitivity of growing season NEE to interannual meteorological variability, due to compensatory responses of photosynthesis and ecosystem respiration. In this modelling study, we show that this NEE buffering is the case also for full annual cycles. We show through a sensitivity analysis that plant traits related to nitrogen are likely key determinants in the compensatory response, through simulated links to photosynthesis and plant respiration. Interestingly, we found a similar temperature sensitivity of the trait-flux couplings for GPP and R<sub>eco</sub>, suggesting that plant traits drive the stabilization of NEE. Further, model analysis indicated that wintertime periods decreased the C sink by 60%, mostly driven by litter heterotrophic respiration. This result emphasizes the importance of wintertime periods and allows a more comprehensive understanding of full annual C dynamics.</p>},
  author       = {López-Blanco, Efrén and Lund, Magnus and Christensen, Torben R. and Tamstorf, Mikkel P. and Smallman, Thomas L. and Slevin, Darren and Westergaard-Nielsen, Andreas and Hansen, Birger U. and Abermann, Jakob and Williams, Mathew},
  issn         = {2169-8953},
  keyword      = {Arctic tundra,ecosystem exchange,ecosystem respiration,gross primary production,plant traits,process-based modeling},
  language     = {eng},
  month        = {07},
  publisher    = {American Geophysical Union},
  series       = {Journal of Geophysical Research - Biogeosciences},
  title        = {Plant Traits are Key Determinants in Buffering the Meteorological Sensitivity of Net Carbon Exchanges of Arctic Tundra},
  url          = {http://dx.doi.org/10.1029/2018JG004386},
  year         = {2018},
}