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Warming and Increased Respiration Have Transformed an Alpine Steppe Ecosystem on the Tibetan Plateau From a Carbon Dioxide Sink Into a Source

Yun, Hanbo ; Tang, Jing LU orcid ; D’Imperio, Ludovica ; Wang, Xiaobo ; Qu, Yang ; Liu, Licheng ; Zhuang, Qianlai ; Zhang, Wenxin LU orcid ; Wu, Qingbai and Chen, Anping , et al. (2022) In Journal of Geophysical Research: Biogeosciences 127(1).
Abstract

Cold region ecosystems store vast amounts of soil organic carbon (C), which upon warming and decomposition can affect the C balance and potentially change these ecosystems from C sinks to carbon dioxide (CO2) sources. We quantified the decadal year-round CO2 flux from an alpine steppe-ecosystem on the Tibetan Plateau using eddy covariance and automatic chamber approaches during a period of significant warming (0.13°C per 10 years; and 0.18°C in the non-growing season alone: 1st October to next 30th April). The results showed that ongoing climate change, mainly warming within the topsoil layers, is the main reason for the site’s change from a sink for to a source of CO2 in the atmosphere.... (More)

Cold region ecosystems store vast amounts of soil organic carbon (C), which upon warming and decomposition can affect the C balance and potentially change these ecosystems from C sinks to carbon dioxide (CO2) sources. We quantified the decadal year-round CO2 flux from an alpine steppe-ecosystem on the Tibetan Plateau using eddy covariance and automatic chamber approaches during a period of significant warming (0.13°C per 10 years; and 0.18°C in the non-growing season alone: 1st October to next 30th April). The results showed that ongoing climate change, mainly warming within the topsoil layers, is the main reason for the site’s change from a sink for to a source of CO2 in the atmosphere. Non-growing-season ecosystem respiration accounted for 51% of the annual ecosystem respiration and has increased significantly. The growing seasons (1st May to 30th September) were consistent CO2 sink periods without significant changes over the study period. Observations revealed high-emission events from the end of the non-growing season to early in the growing season (1st March to fifteenth May), which significantly (p < 0.01) increased at a rate of 22.6 g C m−2 decade−1, ranging from 14.6 ± 10.7 g C m−2 yr−1 in 2012 to 35.3 ± 12.1 g C m−2 yr−1 in 2017. Structural equation modeling suggested that active layer warming was the key factor in explaining changes in ecosystem respiration, leading to significant changes in net ecosystem exchange over the period 2011–2020 and indicated that these changes have already transformed the ecosystem from a CO2 sink into a source. These results can be used to improve our understanding of the sensitivity of ecosystem respiration to increased warming during the non-growing period.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
alpine steppe ecosystem, automatic chamber, carbon sink, eddy covariance, soil respiration, Tibetan Plateau
in
Journal of Geophysical Research: Biogeosciences
volume
127
issue
1
article number
e2021JG006406
publisher
Wiley
external identifiers
  • scopus:85123695684
ISSN
2169-8953
DOI
10.1029/2021JG006406
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2021. American Geophysical Union. All Rights Reserved.
id
26e84230-66d7-48bf-9b9e-ab0abe28d95d
date added to LUP
2022-02-16 14:11:39
date last changed
2022-04-19 01:21:36
@article{26e84230-66d7-48bf-9b9e-ab0abe28d95d,
  abstract     = {{<p>Cold region ecosystems store vast amounts of soil organic carbon (C), which upon warming and decomposition can affect the C balance and potentially change these ecosystems from C sinks to carbon dioxide (CO<sub>2</sub>) sources. We quantified the decadal year-round CO<sub>2</sub> flux from an alpine steppe-ecosystem on the Tibetan Plateau using eddy covariance and automatic chamber approaches during a period of significant warming (0.13°C per 10 years; and 0.18°C in the non-growing season alone: 1st October to next 30th April). The results showed that ongoing climate change, mainly warming within the topsoil layers, is the main reason for the site’s change from a sink for to a source of CO<sub>2</sub> in the atmosphere. Non-growing-season ecosystem respiration accounted for 51% of the annual ecosystem respiration and has increased significantly. The growing seasons (1st May to 30th September) were consistent CO<sub>2</sub> sink periods without significant changes over the study period. Observations revealed high-emission events from the end of the non-growing season to early in the growing season (1st March to fifteenth May), which significantly (p &lt; 0.01) increased at a rate of 22.6 g C m<sup>−2</sup> decade<sup>−1</sup>, ranging from 14.6 ± 10.7 g C m<sup>−2</sup> yr<sup>−1</sup> in 2012 to 35.3 ± 12.1 g C m<sup>−2</sup> yr<sup>−1</sup> in 2017. Structural equation modeling suggested that active layer warming was the key factor in explaining changes in ecosystem respiration, leading to significant changes in net ecosystem exchange over the period 2011–2020 and indicated that these changes have already transformed the ecosystem from a CO<sub>2</sub> sink into a source. These results can be used to improve our understanding of the sensitivity of ecosystem respiration to increased warming during the non-growing period.</p>}},
  author       = {{Yun, Hanbo and Tang, Jing and D’Imperio, Ludovica and Wang, Xiaobo and Qu, Yang and Liu, Licheng and Zhuang, Qianlai and Zhang, Wenxin and Wu, Qingbai and Chen, Anping and Zhu, Qing and Chen, Deliang and Elberling, Bo}},
  issn         = {{2169-8953}},
  keywords     = {{alpine steppe ecosystem; automatic chamber; carbon sink; eddy covariance; soil respiration; Tibetan Plateau}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{Wiley}},
  series       = {{Journal of Geophysical Research: Biogeosciences}},
  title        = {{Warming and Increased Respiration Have Transformed an Alpine Steppe Ecosystem on the Tibetan Plateau From a Carbon Dioxide Sink Into a Source}},
  url          = {{http://dx.doi.org/10.1029/2021JG006406}},
  doi          = {{10.1029/2021JG006406}},
  volume       = {{127}},
  year         = {{2022}},
}