Southern Hemisphere bog persists as a strong carbon sink during droughts

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dc.contributor.authorGoodrich, Jordan Paulen_NZ
dc.contributor.authorCampbell, David I.en_NZ
dc.contributor.authorSchipper, Louis A.en_NZ
dc.date.accessioned2017-10-03T22:17:44Z
dc.date.available2017en_NZ
dc.date.available2017-10-03T22:17:44Z
dc.date.issued2017en_NZ
dc.description.abstractPeatland ecosystems have been important global carbon sinks throughout the Holocene. Most of the research on peatland carbon budgets and effects of variable weather conditions has been done in Northern Hemisphere Sphagnum-dominated systems. Given their importance in other geographic and climatic regions, a better understanding of peatland carbon dynamics is needed across the spectrum of global peatland types. In New Zealand, much of the historic peatland area has been drained for agriculture but little is known about rates of carbon exchange and storage in unaltered peatland remnants that are dominated by the jointed wire-rush, Empodisma robustum. We used eddy covariance to measure ecosystem-scale CO₂ and CH₄ fluxes and a water balance approach to estimate the sub-surface flux of dissolved organic carbon from the largest remaining raised peat bog in New Zealand, Kopuatai bog. The net ecosystem carbon balance (NECB) was estimated over four years, which included two drought summers, a relatively wet summer, and a meteorologically average summer. In all measurement years, the bog was a substantial sink for carbon, ranging from 134.7 gC m⁻² yr⁻¹ to 216.9 gC m⁻² yr⁻¹, owing to the large annual net ecosystem production (−161.8 to −244.9 gCO2-C m⁻² yr⁻¹). Annual methane fluxes were large relative to most Northern Hemisphere peatlands (14.2 to 21.9 gCH4-C  m⁻² yr⁻¹1), although summer and autumn emissions were highly sensitive to dry conditions leading to very predictable seasonality according to water table position. The annual flux of dissolved organic carbon was similar in magnitude to methane emissions but less variable, ranging from 11.7 to 12.8 gC m⁻² yr⁻¹. Dry conditions experienced during late summer droughts led to significant reductions in annual carbon storage, which resulted nearly equally from enhanced ecosystem respiration due to lowered water tables and increased temperatures, and from reduced gross primary production due to vapor pressure deficit-related stresses to the vegetation. However, the net C uptake of Kopuatai bog during drought years was large relative to even the maximum reported NECB from Northern Hemisphere bogs. Furthermore, GWP fluxes indicated the bog was a strong sink for greenhouse gases in all years despite the relatively large annual methane emissions. Our results suggest that adaptations of E. robustum to dry conditions lead to a resilient peatland drought response of the NECB.
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dc.identifier.citationGoodrich, J. P., Campbell, D. I., & Schipper, L. A. (2017). Southern Hemisphere bog persists as a strong carbon sink during droughts. Biogeosciences, 14, 4563–4576. https://doi.org/10.5194/bg-14-4563-2017en
dc.identifier.doi10.5194/bg-14-4563-2017en_NZ
dc.identifier.eissn1810-6285en_NZ
dc.identifier.issn1726-4170en_NZ
dc.identifier.urihttps://hdl.handle.net/10289/11373
dc.language.isoen
dc.publisherCopernicus Publicationsen_NZ
dc.relation.isPartOfBiogeosciencesen_NZ
dc.relation.urihttps://www.biogeosciences.net/14/4563/2017/bg-14-4563-2017-discussion.html
dc.rights© Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License.
dc.titleSouthern Hemisphere bog persists as a strong carbon sink during droughtsen_NZ
dc.typeJournal Article
pubs.begin-page4563
pubs.elements-id206506
pubs.end-page4576
pubs.organisational-group/Waikato
pubs.organisational-group/Waikato/2018 PBRF
pubs.organisational-group/Waikato/FSEN
pubs.organisational-group/Waikato/FSEN/2018 PBRF - FSEN
pubs.organisational-group/Waikato/FSEN/School of Science
pubs.organisational-group/Waikato/FSEN/School of Science/2018 PBRF - School of Science
pubs.user.infoCampbell, David (davec@waikato.ac.nz)
pubs.volume14
uow.relation.urihttps://hdl.handle.net/10289/11393
uow.verification.statusunverified
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