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Drivers of dissolved organic carbon export in a subarctic catchment : Importance of microbial decomposition, sorption-desorption, peatland and lateral flow

Tang, Jing LU ; Yurova, Alla Y. LU ; Schurgers, Guy LU ; Miller, Paul A. LU ; Olin, Stefan LU ; Smith, Benjamin LU ; Siewert, Matthias B.; Olefeldt, David; Pilesjö, Petter LU and Poska, Anneli LU (2018) In Science of the Total Environment 622-623. p.260-274
Abstract

Tundra soils account for 50% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to... (More)

Tundra soils account for 50% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to link this flux to other ecosystem processes. The extended LPJ-GUESS is compared to observed DOC export at Stordalen catchment in northern Sweden. Vegetation communities include flood-tolerant graminoids (Eriophorum) and Sphagnum moss, birch forest and dwarf shrub communities. The processes, sorption-desorption and microbial decomposition (DOC production and mineralization) are found to contribute most to the variance in DOC export based on a detailed variance-based Sobol sensitivity analysis (SA) at grid cell-level. Catchment-level SA shows that the highest mean DOC exports come from the Eriophorum peatland (fen). A comparison with observations shows that the model captures the seasonality of DOC fluxes. Two catchment simulations, one without water lateral routing and one without peatland processes, were compared with the catchment simulations with all processes. The comparison showed that the current implementation of catchment lateral flow and peatland processes in LPJ-GUESS are essential to capture catchment-level DOC dynamics and indicate the model is at an appropriate level of complexity to represent the main mechanism of DOC dynamics in soils. The extended model provides a new tool to investigate potential interactions among climate change, vegetation dynamics, soil hydrology and DOC dynamics at both stand-alone to catchment scales.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
DOC flux, Lateral flow, LPJ-GUESS, Peatland, Sorption-desorption, Subarctic catchment
in
Science of the Total Environment
volume
622-623
pages
15 pages
publisher
Elsevier
external identifiers
  • scopus:85036617192
ISSN
0048-9697
DOI
10.1016/j.scitotenv.2017.11.252
language
English
LU publication?
yes
id
0bd8bbc9-a51c-4f00-bbb8-fbbfcea932d7
date added to LUP
2017-12-20 13:53:05
date last changed
2018-05-29 10:53:56
@article{0bd8bbc9-a51c-4f00-bbb8-fbbfcea932d7,
  abstract     = {<p>Tundra soils account for 50% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to link this flux to other ecosystem processes. The extended LPJ-GUESS is compared to observed DOC export at Stordalen catchment in northern Sweden. Vegetation communities include flood-tolerant graminoids (Eriophorum) and Sphagnum moss, birch forest and dwarf shrub communities. The processes, sorption-desorption and microbial decomposition (DOC production and mineralization) are found to contribute most to the variance in DOC export based on a detailed variance-based Sobol sensitivity analysis (SA) at grid cell-level. Catchment-level SA shows that the highest mean DOC exports come from the Eriophorum peatland (fen). A comparison with observations shows that the model captures the seasonality of DOC fluxes. Two catchment simulations, one without water lateral routing and one without peatland processes, were compared with the catchment simulations with all processes. The comparison showed that the current implementation of catchment lateral flow and peatland processes in LPJ-GUESS are essential to capture catchment-level DOC dynamics and indicate the model is at an appropriate level of complexity to represent the main mechanism of DOC dynamics in soils. The extended model provides a new tool to investigate potential interactions among climate change, vegetation dynamics, soil hydrology and DOC dynamics at both stand-alone to catchment scales.</p>},
  author       = {Tang, Jing and Yurova, Alla Y. and Schurgers, Guy and Miller, Paul A. and Olin, Stefan and Smith, Benjamin and Siewert, Matthias B. and Olefeldt, David and Pilesjö, Petter and Poska, Anneli},
  issn         = {0048-9697},
  keyword      = {DOC flux,Lateral flow,LPJ-GUESS,Peatland,Sorption-desorption,Subarctic catchment},
  language     = {eng},
  month        = {05},
  pages        = {260--274},
  publisher    = {Elsevier},
  series       = {Science of the Total Environment},
  title        = {Drivers of dissolved organic carbon export in a subarctic catchment : Importance of microbial decomposition, sorption-desorption, peatland and lateral flow},
  url          = {http://dx.doi.org/10.1016/j.scitotenv.2017.11.252},
  volume       = {622-623},
  year         = {2018},
}