Advanced

Multi-year data-model evaluation reveals the importance of nutrient availability over climate in arctic ecosystem C dynamics

López-Blanco, Efrén ; Jackowicz-Korczynski, Marcin LU ; Mastepanov, Mikhail LU ; Skov, Kirstine ; Westergaard-Nielsen, Andreas ; Williams, Mathew and Christensen, Torben R. LU (2020) In Environmental Research Letters 15(9).
Abstract

Arctic tundra is a globally important store for carbon (C). However, there is a lack of reference sites characterising C exchange dynamics across annual cycles. Based on the Greenland Ecosystem Monitoring (GEM) programme, here we present 9-11 years of flux and ecosystem data across the period 2008-2018 from two wetland sites in Greenland: Zackenberg (74°N) and Kobbefjord (64°N). The Zackenberg fen was a strong C sink despite its higher latitude and shorter growing seasons compared to the Kobbefjord fen. On average the ecosystem in Zackenberg took up ∼-50 g C m-2 yr-1 (range of +21 to-90 g C m-2 yr-1), more than twice that of Kobbefjord (mean ∼-18 g C m-2 yr-1, and range of +41 to-41 g C m-2 yr-1). The larger net carbon sequestration in... (More)

Arctic tundra is a globally important store for carbon (C). However, there is a lack of reference sites characterising C exchange dynamics across annual cycles. Based on the Greenland Ecosystem Monitoring (GEM) programme, here we present 9-11 years of flux and ecosystem data across the period 2008-2018 from two wetland sites in Greenland: Zackenberg (74°N) and Kobbefjord (64°N). The Zackenberg fen was a strong C sink despite its higher latitude and shorter growing seasons compared to the Kobbefjord fen. On average the ecosystem in Zackenberg took up ∼-50 g C m-2 yr-1 (range of +21 to-90 g C m-2 yr-1), more than twice that of Kobbefjord (mean ∼-18 g C m-2 yr-1, and range of +41 to-41 g C m-2 yr-1). The larger net carbon sequestration in Zackenberg fen was associated with higher leaf nitrogen (71%), leaf area index (140%), and plant quality (i.e. C:N ratio; 36%). Additional evidence from in-situ measurements includes 3 times higher levels of dissolved organic carbon in soils and 5 times more available plant nutrients, including dissolved organic nitrogen (N) and nitrates, in Zackenberg. Simulations using the soil-plant-atmosphere ecosystem model showed that Zackenberg's stronger CO2 sink could be related to measured differences in plant nutrients, and their effects on photosynthesis and respiration. The model explained 69% of the variability of net ecosystem exchange of CO2, 80% for photosynthesis and 71% for respiration over 11 years at Zackenberg, similar to previous results at Kobbefjord (73%, 73%, and 50%, respectively, over 8 years). We conclude that growing season limitations of plant phenology on net C uptake have been more than counterbalanced by the increased leaf nutrient content at the Zackenberg site.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Arctic tundra, Ecosystem respiration, Greenland, Net ecosystem exchange, Nutrient availability, Photosynthesis
in
Environmental Research Letters
volume
15
issue
9
article number
094007
publisher
IOP Publishing
external identifiers
  • scopus:85090917228
ISSN
1748-9318
DOI
10.1088/1748-9326/ab865b
language
English
LU publication?
yes
id
03aa1242-a44f-4c2b-bd3f-092d4d5186fd
date added to LUP
2020-10-01 13:35:32
date last changed
2020-10-02 01:59:52
@article{03aa1242-a44f-4c2b-bd3f-092d4d5186fd,
  abstract     = {<p>Arctic tundra is a globally important store for carbon (C). However, there is a lack of reference sites characterising C exchange dynamics across annual cycles. Based on the Greenland Ecosystem Monitoring (GEM) programme, here we present 9-11 years of flux and ecosystem data across the period 2008-2018 from two wetland sites in Greenland: Zackenberg (74°N) and Kobbefjord (64°N). The Zackenberg fen was a strong C sink despite its higher latitude and shorter growing seasons compared to the Kobbefjord fen. On average the ecosystem in Zackenberg took up ∼-50 g C m-2 yr-1 (range of +21 to-90 g C m-2 yr-1), more than twice that of Kobbefjord (mean ∼-18 g C m-2 yr-1, and range of +41 to-41 g C m-2 yr-1). The larger net carbon sequestration in Zackenberg fen was associated with higher leaf nitrogen (71%), leaf area index (140%), and plant quality (i.e. C:N ratio; 36%). Additional evidence from in-situ measurements includes 3 times higher levels of dissolved organic carbon in soils and 5 times more available plant nutrients, including dissolved organic nitrogen (N) and nitrates, in Zackenberg. Simulations using the soil-plant-atmosphere ecosystem model showed that Zackenberg's stronger CO2 sink could be related to measured differences in plant nutrients, and their effects on photosynthesis and respiration. The model explained 69% of the variability of net ecosystem exchange of CO2, 80% for photosynthesis and 71% for respiration over 11 years at Zackenberg, similar to previous results at Kobbefjord (73%, 73%, and 50%, respectively, over 8 years). We conclude that growing season limitations of plant phenology on net C uptake have been more than counterbalanced by the increased leaf nutrient content at the Zackenberg site. </p>},
  author       = {López-Blanco, Efrén and Jackowicz-Korczynski, Marcin and Mastepanov, Mikhail and Skov, Kirstine and Westergaard-Nielsen, Andreas and Williams, Mathew and Christensen, Torben R.},
  issn         = {1748-9318},
  language     = {eng},
  month        = {09},
  number       = {9},
  publisher    = {IOP Publishing},
  series       = {Environmental Research Letters},
  title        = {Multi-year data-model evaluation reveals the importance of nutrient availability over climate in arctic ecosystem C dynamics},
  url          = {http://dx.doi.org/10.1088/1748-9326/ab865b},
  doi          = {10.1088/1748-9326/ab865b},
  volume       = {15},
  year         = {2020},
}