Soil CO2 efflux in a degraded raised bog is regulated by water table depth rather than recent plant assimilate

U. H. Kritzler, R. R E Artz, D. Johnson*

*Corresponding author for this work

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Understanding the climatic and biological factors that regulate soil carbon dioxide (CO2) efflux is crucial in peatlands because they contain a large proportion of terrestrial carbon (C). We predicted that rainfall reduction would increase soil CO2 efflux, and that cessation of below-ground allocation of recent plant assimilate would reduce soil CO2 efflux. These predictions were tested in the field using rainfall shelters that allowed a maximum of 40% of rainfall onto 2 × 2 m plots by diverting rainwater from the shelter roofs with guttering, and by girdling stems of the dominant plant, Calluna vulgaris, for two years. We also used13CO2-pulse labelling of intact monoliths at ambient CO2 concentrations to trace recent assimilate from plant shoots to roots, bulk soil, leachate, dissolved organic carbon (DOC) and soil CO2 efflux. Soil CO2efflux in the sheltered plots increased in Year 1 but not in Year 2, and we found a positive relationship between soil CO2 efflux and water table depth. Our data indicate that lowering the water table below a critical threshold (15–20 cm) affects soil CO2 efflux. Girdling of C. vulgaris shoots resulted in no measurable reduction in soil CO2 efflux, while only ~3% of13C fixed by shoots was recovered in soil CO2 efflux and DOC in the 20 days after labelling. Our findings show that below-ground allocation of recent assimilate from C. vulgaris plants > 6 years old has little impact on soil CO2 efflux.

Original languageEnglish
Article number01
JournalMires and Peat
Volume17
DOIs
Publication statusPublished - 2016

Fingerprint

raised bog
bogs
water table
carbon dioxide
soil
Calluna vulgaris
shoot
rain
girdling
shelter
rainfall
dissolved organic carbon
shoots
soil carbon
rainwater
peatland
organic soil
roof
leachate
peatlands

Keywords

  • CO pulse labelling
  • Calluna vulgaris
  • Carbon cycle
  • Degraded peat bog
  • Girdling

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Soil Science
  • Ecology
  • Nature and Landscape Conservation

Cite this

Soil CO2 efflux in a degraded raised bog is regulated by water table depth rather than recent plant assimilate. / Kritzler, U. H.; Artz, R. R E; Johnson, D.

In: Mires and Peat, Vol. 17, 01, 2016.

Research output: Contribution to journalArticle

@article{dc4ddd81d9f64c519e39dc61aa706019,
title = "Soil CO2 efflux in a degraded raised bog is regulated by water table depth rather than recent plant assimilate",
abstract = "Understanding the climatic and biological factors that regulate soil carbon dioxide (CO2) efflux is crucial in peatlands because they contain a large proportion of terrestrial carbon (C). We predicted that rainfall reduction would increase soil CO2 efflux, and that cessation of below-ground allocation of recent plant assimilate would reduce soil CO2 efflux. These predictions were tested in the field using rainfall shelters that allowed a maximum of 40{\%} of rainfall onto 2 × 2 m plots by diverting rainwater from the shelter roofs with guttering, and by girdling stems of the dominant plant, Calluna vulgaris, for two years. We also used13CO2-pulse labelling of intact monoliths at ambient CO2 concentrations to trace recent assimilate from plant shoots to roots, bulk soil, leachate, dissolved organic carbon (DOC) and soil CO2 efflux. Soil CO2efflux in the sheltered plots increased in Year 1 but not in Year 2, and we found a positive relationship between soil CO2 efflux and water table depth. Our data indicate that lowering the water table below a critical threshold (15–20 cm) affects soil CO2 efflux. Girdling of C. vulgaris shoots resulted in no measurable reduction in soil CO2 efflux, while only ~3{\%} of13C fixed by shoots was recovered in soil CO2 efflux and DOC in the 20 days after labelling. Our findings show that below-ground allocation of recent assimilate from C. vulgaris plants > 6 years old has little impact on soil CO2 efflux.",
keywords = "CO pulse labelling, Calluna vulgaris, Carbon cycle, Degraded peat bog, Girdling",
author = "Kritzler, {U. H.} and Artz, {R. R E} and D. Johnson",
note = "ACKNOWLEDGEMENTS We thank Leys Estate for access and permission to use Red Moss of Candyglirach, particularly Thys Simpson for onsite help; and Barry Thornton, Dave Hadwen and Ken Cruickshank for technical support. This work was funded by a Natural Environment Research Council (NERC) Open CASE award(NE/F013760/1) with the James Hutton Institute (JHI).",
year = "2016",
doi = "10.19189/MaP.2015.OMB.203",
language = "English",
volume = "17",
journal = "Mires and Peat",
issn = "1819-754X",
publisher = "The International Mire Conservation Group (IMCG)",

}

TY - JOUR

T1 - Soil CO2 efflux in a degraded raised bog is regulated by water table depth rather than recent plant assimilate

AU - Kritzler, U. H.

AU - Artz, R. R E

AU - Johnson, D.

N1 - ACKNOWLEDGEMENTS We thank Leys Estate for access and permission to use Red Moss of Candyglirach, particularly Thys Simpson for onsite help; and Barry Thornton, Dave Hadwen and Ken Cruickshank for technical support. This work was funded by a Natural Environment Research Council (NERC) Open CASE award(NE/F013760/1) with the James Hutton Institute (JHI).

PY - 2016

Y1 - 2016

N2 - Understanding the climatic and biological factors that regulate soil carbon dioxide (CO2) efflux is crucial in peatlands because they contain a large proportion of terrestrial carbon (C). We predicted that rainfall reduction would increase soil CO2 efflux, and that cessation of below-ground allocation of recent plant assimilate would reduce soil CO2 efflux. These predictions were tested in the field using rainfall shelters that allowed a maximum of 40% of rainfall onto 2 × 2 m plots by diverting rainwater from the shelter roofs with guttering, and by girdling stems of the dominant plant, Calluna vulgaris, for two years. We also used13CO2-pulse labelling of intact monoliths at ambient CO2 concentrations to trace recent assimilate from plant shoots to roots, bulk soil, leachate, dissolved organic carbon (DOC) and soil CO2 efflux. Soil CO2efflux in the sheltered plots increased in Year 1 but not in Year 2, and we found a positive relationship between soil CO2 efflux and water table depth. Our data indicate that lowering the water table below a critical threshold (15–20 cm) affects soil CO2 efflux. Girdling of C. vulgaris shoots resulted in no measurable reduction in soil CO2 efflux, while only ~3% of13C fixed by shoots was recovered in soil CO2 efflux and DOC in the 20 days after labelling. Our findings show that below-ground allocation of recent assimilate from C. vulgaris plants > 6 years old has little impact on soil CO2 efflux.

AB - Understanding the climatic and biological factors that regulate soil carbon dioxide (CO2) efflux is crucial in peatlands because they contain a large proportion of terrestrial carbon (C). We predicted that rainfall reduction would increase soil CO2 efflux, and that cessation of below-ground allocation of recent plant assimilate would reduce soil CO2 efflux. These predictions were tested in the field using rainfall shelters that allowed a maximum of 40% of rainfall onto 2 × 2 m plots by diverting rainwater from the shelter roofs with guttering, and by girdling stems of the dominant plant, Calluna vulgaris, for two years. We also used13CO2-pulse labelling of intact monoliths at ambient CO2 concentrations to trace recent assimilate from plant shoots to roots, bulk soil, leachate, dissolved organic carbon (DOC) and soil CO2 efflux. Soil CO2efflux in the sheltered plots increased in Year 1 but not in Year 2, and we found a positive relationship between soil CO2 efflux and water table depth. Our data indicate that lowering the water table below a critical threshold (15–20 cm) affects soil CO2 efflux. Girdling of C. vulgaris shoots resulted in no measurable reduction in soil CO2 efflux, while only ~3% of13C fixed by shoots was recovered in soil CO2 efflux and DOC in the 20 days after labelling. Our findings show that below-ground allocation of recent assimilate from C. vulgaris plants > 6 years old has little impact on soil CO2 efflux.

KW - CO pulse labelling

KW - Calluna vulgaris

KW - Carbon cycle

KW - Degraded peat bog

KW - Girdling

UR - http://www.scopus.com/inward/record.url?scp=84959508706&partnerID=8YFLogxK

U2 - 10.19189/MaP.2015.OMB.203

DO - 10.19189/MaP.2015.OMB.203

M3 - Article

AN - SCOPUS:84959508706

VL - 17

JO - Mires and Peat

JF - Mires and Peat

SN - 1819-754X

M1 - 01

ER -