Multi-year data-model evaluation reveals the importance of nutrient availability over climate in arctic ecosystem C dynamics
(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)
- author
- López-Blanco, Efrén ; Jackowicz-Korczynski, Marcin LU ; Mastepanov, Mikhail LU ; Skov, Kirstine ; Westergaard-Nielsen, Andreas ; Williams, Mathew and Christensen, Torben R. LU
- organization
- publishing date
- 2020-09-01
- 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
- 2022-04-19 01:00:32
@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}},
keywords = {{Arctic tundra; Ecosystem respiration; Greenland; Net ecosystem exchange; Nutrient availability; Photosynthesis}},
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}},
}