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CO2 emissions from an undrained tropical peatland: Interacting influences of temperature, shading and water table depth.
Glob Chang Biol. 2019 09; 25(9):2885-2899.GC

Abstract

Emission of CO2 from tropical peatlands is an important component of the global carbon budget. Over days to months, these fluxes are largely controlled by water table depth. However, the diurnal cycle is less well understood, in part, because most measurements have been collected daily at midday. We used an automated chamber system to make hourly measurements of peat surface CO2 emissions from chambers root-cut to 30 cm. We then used these data to disentangle the relationship between temperature, water table and heterotrophic respiration (Rhet). We made two central observations. First, we found strong diurnal cycles in CO2 flux and near-surface peat temperature (<10 cm depth), both peaking at midday. The magnitude of diurnal oscillations was strongly influenced by shading and water table depth, highlighting the limitations of relying on daytime measurements and/or a single correction factor to remove daytime bias in flux measurements. Second, we found mean daily Rhet had a strong linear relationship to the depth of the water table, and under flooded conditions, Rhet was small and constant. We used this relationship between Rhet and water table depth to estimate carbon export from both Rhet and dissolved organic carbon over the course of a year based on water table records. Rhet dominates annual carbon export, demonstrating the potential for peatland drainage to increase regional CO2 emissions. Finally, we discuss an apparent incompatibility between hourly and daily average observations of CO2 flux, water table and temperature: water table and daily average flux data suggest that CO2 is produced across the entire unsaturated peat profile, whereas temperature and hourly flux data appear to suggest that CO2 fluxes are controlled by very near surface peat. We explore how temperature-, moisture- and gas transport-related mechanisms could cause mean CO2 emissions to increase linearly with water table depth and also have a large diurnal cycle.

Authors+Show Affiliations

Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.EcoLab (Laboratoire Écologie Fonctionnelle et Environnement), Université de Toulouse, CNRS, INPT, UPS, Toulouse, France.Forestry Department, Ministry of Industry and Primary Resources, Bandar Seri Begawan, Brunei Darussalam.Center for Environmental Sensing and Modeling, Singapore-MIT Alliance for Research and Technology, Singapore.Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts. Center for Environmental Sensing and Modeling, Singapore-MIT Alliance for Research and Technology, Singapore.Center for Environmental Sensing and Modeling, Singapore-MIT Alliance for Research and Technology, Singapore.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

31100190

Citation

Hoyt, Alison M., et al. "CO2 Emissions From an Undrained Tropical Peatland: Interacting Influences of Temperature, Shading and Water Table Depth." Global Change Biology, vol. 25, no. 9, 2019, pp. 2885-2899.
Hoyt AM, Gandois L, Eri J, et al. CO2 emissions from an undrained tropical peatland: Interacting influences of temperature, shading and water table depth. Glob Chang Biol. 2019;25(9):2885-2899.
Hoyt, A. M., Gandois, L., Eri, J., Kai, F. M., Harvey, C. F., & Cobb, A. R. (2019). CO2 emissions from an undrained tropical peatland: Interacting influences of temperature, shading and water table depth. Global Change Biology, 25(9), 2885-2899. https://doi.org/10.1111/gcb.14702
Hoyt AM, et al. CO2 Emissions From an Undrained Tropical Peatland: Interacting Influences of Temperature, Shading and Water Table Depth. Glob Chang Biol. 2019;25(9):2885-2899. PubMed PMID: 31100190.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - CO2 emissions from an undrained tropical peatland: Interacting influences of temperature, shading and water table depth. AU - Hoyt,Alison M, AU - Gandois,Laure, AU - Eri,Jangarun, AU - Kai,Fuu Ming, AU - Harvey,Charles F, AU - Cobb,Alexander R, Y1 - 2019/07/05/ PY - 2018/11/15/received PY - 2019/02/20/revised PY - 2019/03/28/accepted PY - 2019/5/18/pubmed PY - 2019/10/12/medline PY - 2019/5/18/entrez KW - CO2 flux KW - Southeast Asia KW - closed dynamic chamber technique KW - diurnal cycle KW - heterotrophic respiration KW - soil temperature KW - tropical peatland SP - 2885 EP - 2899 JF - Global change biology JO - Glob Chang Biol VL - 25 IS - 9 N2 - Emission of CO2 from tropical peatlands is an important component of the global carbon budget. Over days to months, these fluxes are largely controlled by water table depth. However, the diurnal cycle is less well understood, in part, because most measurements have been collected daily at midday. We used an automated chamber system to make hourly measurements of peat surface CO2 emissions from chambers root-cut to 30 cm. We then used these data to disentangle the relationship between temperature, water table and heterotrophic respiration (Rhet). We made two central observations. First, we found strong diurnal cycles in CO2 flux and near-surface peat temperature (<10 cm depth), both peaking at midday. The magnitude of diurnal oscillations was strongly influenced by shading and water table depth, highlighting the limitations of relying on daytime measurements and/or a single correction factor to remove daytime bias in flux measurements. Second, we found mean daily Rhet had a strong linear relationship to the depth of the water table, and under flooded conditions, Rhet was small and constant. We used this relationship between Rhet and water table depth to estimate carbon export from both Rhet and dissolved organic carbon over the course of a year based on water table records. Rhet dominates annual carbon export, demonstrating the potential for peatland drainage to increase regional CO2 emissions. Finally, we discuss an apparent incompatibility between hourly and daily average observations of CO2 flux, water table and temperature: water table and daily average flux data suggest that CO2 is produced across the entire unsaturated peat profile, whereas temperature and hourly flux data appear to suggest that CO2 fluxes are controlled by very near surface peat. We explore how temperature-, moisture- and gas transport-related mechanisms could cause mean CO2 emissions to increase linearly with water table depth and also have a large diurnal cycle. SN - 1365-2486 UR - https://www.unboundmedicine.com/medline/citation/31100190/CO2_emissions_from_an_undrained_tropical_peatland:_Interacting_influences_of_temperature_shading_and_water_table_depth_ L2 - https://doi.org/10.1111/gcb.14702 DB - PRIME DP - Unbound Medicine ER -
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