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Modelling impacts of lateral N flows and seasonal warming on an arctic footslope ecosystem N budget and N2O emissions based on species-level responses

Rasmussen, Laura H. ; Zhang, Wenxin LU orcid ; Ambus, Per ; Jansson, Per Erik ; Kitzler, Barbara and Elberling, Bo (2022) In Biogeochemistry 158(2). p.195-213
Abstract

Future Arctic tundra primary productivity and vegetation community composition will partly be determined by nitrogen (N) availability in a warmer climate. N mineralization rates are predicted to increase in both winter and summer, but because N demand and –mobility varies across seasons, the fate of mineralized N remains uncertain. N mineralized in winter is released in a “pulse” upon snowmelt and soil thaw, with the potential for lateral redistribution in the landscape. In summer, the release is into an active rhizosphere with high local biological N demand. In this study, we investigated the ecosystem sensitivity to increased lateral N input and near-surface warming, respectively and in combination, with a numerical ecosystem model... (More)

Future Arctic tundra primary productivity and vegetation community composition will partly be determined by nitrogen (N) availability in a warmer climate. N mineralization rates are predicted to increase in both winter and summer, but because N demand and –mobility varies across seasons, the fate of mineralized N remains uncertain. N mineralized in winter is released in a “pulse” upon snowmelt and soil thaw, with the potential for lateral redistribution in the landscape. In summer, the release is into an active rhizosphere with high local biological N demand. In this study, we investigated the ecosystem sensitivity to increased lateral N input and near-surface warming, respectively and in combination, with a numerical ecosystem model (CoupModel) parameterized to simulate ecosystem biogeochemistry for a tundra heath ecosystem in West Greenland. Both measurements and model results indicated that plants were poor utilizers of increased early-season lateral N input, indicating that higher winter N mineralization rates may have limited impact on plant growth and carbon (C) sequestration for a hillslope ecosystem. The model further suggested that, although deciduous shrubs were the plant type with overall most lateral N gain, evergreen shrubs appear to have a comparative advantage utilizing early-season N. In contrast, near-surface summer warming increased plant biomass and N uptake, moving N from soil to plant N pools, and offered an advantage to deciduous plants. Neither simulated high lateral N fluxes nor near-surface soil warming suggests that mesic tundra heaths will be important sources of N2O under warmer conditions. Our work highlights how winter and summer warming may play different roles in tundra ecosystem N and C budgets depending on plant community composition.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Arctic tundra, Climate change, CoupModel, Solute transport, Winter N mineralization
in
Biogeochemistry
volume
158
issue
2
pages
19 pages
publisher
Springer
external identifiers
  • scopus:85124398071
ISSN
0168-2563
DOI
10.1007/s10533-022-00894-z
language
English
LU publication?
yes
additional info
Funding Information: We gratefully acknowledge the financial support from the Danish National Research Foundation (CENPERM DNRF100). Funding Information: We gratefully acknowledge the financial support from the Danish National Research Foundation (CENPERM DNRF100). A. Michelsen and K. Rousk kindly helped with knowledge and advice. Zhang W. acknowledged grant from the Swedish Research Council VR 2020-05338. This study is a contribution to the strategic research areas Modeling the Regional and Global Earth System (MERGE) and Biodiversity and Ecosystem Services in a Changing Climate (BECC) at Lund University. Funding Information: We gratefully acknowledge the financial support from the Danish National Research Foundation (CENPERM DNRF100). A. Michelsen and K. Rousk kindly helped with knowledge and advice. Zhang W. acknowledged grant from the Swedish Research Council VR 2020-05338.?This study is a contribution to the strategic research areas Modeling the Regional and Global Earth System (MERGE) and Biodiversity and Ecosystem Services in a Changing Climate (BECC) at Lund University. Publisher Copyright: © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
id
d1db3d45-b2f1-4edb-a76b-96af4c94d5bf
date added to LUP
2022-04-07 14:21:10
date last changed
2022-04-22 22:51:11
@article{d1db3d45-b2f1-4edb-a76b-96af4c94d5bf,
  abstract     = {{<p>Future Arctic tundra primary productivity and vegetation community composition will partly be determined by nitrogen (N) availability in a warmer climate. N mineralization rates are predicted to increase in both winter and summer, but because N demand and –mobility varies across seasons, the fate of mineralized N remains uncertain. N mineralized in winter is released in a “pulse” upon snowmelt and soil thaw, with the potential for lateral redistribution in the landscape. In summer, the release is into an active rhizosphere with high local biological N demand. In this study, we investigated the ecosystem sensitivity to increased lateral N input and near-surface warming, respectively and in combination, with a numerical ecosystem model (CoupModel) parameterized to simulate ecosystem biogeochemistry for a tundra heath ecosystem in West Greenland. Both measurements and model results indicated that plants were poor utilizers of increased early-season lateral N input, indicating that higher winter N mineralization rates may have limited impact on plant growth and carbon (C) sequestration for a hillslope ecosystem. The model further suggested that, although deciduous shrubs were the plant type with overall most lateral N gain, evergreen shrubs appear to have a comparative advantage utilizing early-season N. In contrast, near-surface summer warming increased plant biomass and N uptake, moving N from soil to plant N pools, and offered an advantage to deciduous plants. Neither simulated high lateral N fluxes nor near-surface soil warming suggests that mesic tundra heaths will be important sources of N<sub>2</sub>O under warmer conditions. Our work highlights how winter and summer warming may play different roles in tundra ecosystem N and C budgets depending on plant community composition.</p>}},
  author       = {{Rasmussen, Laura H. and Zhang, Wenxin and Ambus, Per and Jansson, Per Erik and Kitzler, Barbara and Elberling, Bo}},
  issn         = {{0168-2563}},
  keywords     = {{Arctic tundra; Climate change; CoupModel; Solute transport; Winter N mineralization}},
  language     = {{eng}},
  number       = {{2}},
  pages        = {{195--213}},
  publisher    = {{Springer}},
  series       = {{Biogeochemistry}},
  title        = {{Modelling impacts of lateral N flows and seasonal warming on an arctic footslope ecosystem N budget and N<sub>2</sub>O emissions based on species-level responses}},
  url          = {{http://dx.doi.org/10.1007/s10533-022-00894-z}},
  doi          = {{10.1007/s10533-022-00894-z}},
  volume       = {{158}},
  year         = {{2022}},
}