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Mineral Soils Are an Important Intermediate Storage Pool of Black Carbon in Fennoscandian Boreal Forests

Eckdahl, Johan A. LU orcid ; Rodriguez, Pere Casal ; Kristensen, Jeppe A. ; Metcalfe, Daniel B. LU and Ljung, Karl LU orcid (2022) In Global Biogeochemical Cycles 36(11).
Abstract

Approximately 40% of earth's carbon (C) stored in land vegetation and soil is within the boreal region. This large C pool is subjected to substantial removals and transformations during periodic wildfire. Fire-altered C, commonly known as pyrogenic carbon (PyC), plays a significant role in forest ecosystem functioning and composes a considerable fraction of C transport to limnic and oceanic sediments. While PyC stores are beginning to be quantified globally, knowledge is lacking regarding the drivers of their production and transport across ecosystems. This study used the chemo-thermal oxidation at 375°C (CTO-375) method to isolate a particularly refractory subset of PyC compounds, here called black carbon (BC), finding an average... (More)

Approximately 40% of earth's carbon (C) stored in land vegetation and soil is within the boreal region. This large C pool is subjected to substantial removals and transformations during periodic wildfire. Fire-altered C, commonly known as pyrogenic carbon (PyC), plays a significant role in forest ecosystem functioning and composes a considerable fraction of C transport to limnic and oceanic sediments. While PyC stores are beginning to be quantified globally, knowledge is lacking regarding the drivers of their production and transport across ecosystems. This study used the chemo-thermal oxidation at 375°C (CTO-375) method to isolate a particularly refractory subset of PyC compounds, here called black carbon (BC), finding an average increase of 11.6 g BC m−2 at 1 year postfire in 50 separate wildfires occurring in Sweden during 2018. These increases could not be linked to proposed drivers, however BC storage in 50 additional nearby unburnt soils related strongly to soil mass while its proportion of the larger C pool related negatively to soil C:N. Fire approximately doubled BC stocks in the mineral layer but had no significant effect on BC in the organic layer where it was likely produced. Suppressed decomposition rates and low heating during fire in mineral subsoil relative to upper layers suggests potential removals of the doubled mineral layer BC are more likely transported out of the soil system than degraded in situ. Therefore, mineral soils are suggested to be an important storage pool for BC that can buffer short-term (production in fire) and long-term (cross-ecosystem transport) BC cycling.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
black carbon, boreal wildfire, carbon cycle, fire severity, mineral soil, pyrogenic carbon
in
Global Biogeochemical Cycles
volume
36
issue
11
article number
e2022GB007489
publisher
American Geophysical Union (AGU)
external identifiers
  • scopus:85142896880
  • pmid:36582662
ISSN
0886-6236
DOI
10.1029/2022GB007489
language
English
LU publication?
yes
id
52ead829-a37e-4e2a-96ca-4f370cb8fabd
date added to LUP
2022-12-23 11:42:55
date last changed
2024-06-12 00:05:33
@article{52ead829-a37e-4e2a-96ca-4f370cb8fabd,
  abstract     = {{<p>Approximately 40% of earth's carbon (C) stored in land vegetation and soil is within the boreal region. This large C pool is subjected to substantial removals and transformations during periodic wildfire. Fire-altered C, commonly known as pyrogenic carbon (PyC), plays a significant role in forest ecosystem functioning and composes a considerable fraction of C transport to limnic and oceanic sediments. While PyC stores are beginning to be quantified globally, knowledge is lacking regarding the drivers of their production and transport across ecosystems. This study used the chemo-thermal oxidation at 375°C (CTO-375) method to isolate a particularly refractory subset of PyC compounds, here called black carbon (BC), finding an average increase of 11.6 g BC m<sup>−2</sup> at 1 year postfire in 50 separate wildfires occurring in Sweden during 2018. These increases could not be linked to proposed drivers, however BC storage in 50 additional nearby unburnt soils related strongly to soil mass while its proportion of the larger C pool related negatively to soil C:N. Fire approximately doubled BC stocks in the mineral layer but had no significant effect on BC in the organic layer where it was likely produced. Suppressed decomposition rates and low heating during fire in mineral subsoil relative to upper layers suggests potential removals of the doubled mineral layer BC are more likely transported out of the soil system than degraded in situ. Therefore, mineral soils are suggested to be an important storage pool for BC that can buffer short-term (production in fire) and long-term (cross-ecosystem transport) BC cycling.</p>}},
  author       = {{Eckdahl, Johan A. and Rodriguez, Pere Casal and Kristensen, Jeppe A. and Metcalfe, Daniel B. and Ljung, Karl}},
  issn         = {{0886-6236}},
  keywords     = {{black carbon; boreal wildfire; carbon cycle; fire severity; mineral soil; pyrogenic carbon}},
  language     = {{eng}},
  number       = {{11}},
  publisher    = {{American Geophysical Union (AGU)}},
  series       = {{Global Biogeochemical Cycles}},
  title        = {{Mineral Soils Are an Important Intermediate Storage Pool of Black Carbon in Fennoscandian Boreal Forests}},
  url          = {{http://dx.doi.org/10.1029/2022GB007489}},
  doi          = {{10.1029/2022GB007489}},
  volume       = {{36}},
  year         = {{2022}},
}