Root-derived CO2 flux from a tropical peatland

Girkin, Nicholas T.; Turner, Benjamín L.; Ostle, Nicholas J.; Sjögersten, Sofie

doi:10.1007/s11273-018-9617-8

Cited by 16 publications

(16 citation statements)

References 41 publications

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“…While much smaller compared to the trees and other plants in the intact forest, these fern roots are much more ubiquitous. As described in the methods section, our collars were about 5–10 cm in the peat, hence root respiration could not be completely excluded and could be the major component of the total R eco , consistent with previous studies (Girkin, Turner, Ostle, & Sjögersten, 2018; Melling, Yun Tan, Goh, & Hatano, 2013).…”

Section: Discussionsupporting

confidence: 81%

Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH₄ flux

Lupascu

Akhtar

Smith

et al. 2020

Global Change Biology

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Tropical peatlands hold about 15%-19% of the global peat carbon (C) pool of which 77% is stored in the peat swamp forests (PSFs) of Southeast Asia. Nonetheless, these PSFs have been drained, exploited for timber and land for agriculture, leading to frequent fires in the region. The physico-chemical characteristics of peat, as well as the hydrology of PSFs are affected after a fire, during which the ecosystem can act as a C source for decades, as C emissions to the atmosphere exceed photosynthesis. In this work, we studied the longer-term impact of fires on C cycling in tropical PSFs, hence we quantified the magnitude and patterns of C loss (CO 2 , CH 4 and dissolved organic carbon) and soil-water quality characteristics in an intact and a degraded burnt PSF in Brunei Darussalam affected by seven fires over the last 40 years. We used natural tracers such as 14 C to investigate the age and sources of C contributing to ecosystem respiration (R eco) and CH 4 , while we continuously monitored soil temperature and water table (WT) level from June 2017 to January 2019. Our results showed a major difference in the physico-chemical parameters, which in turn affected C dynamics, especially CH 4. Methane effluxes were higher in fire-affected areas (7.8 ± 2.2 mg CH 4 m −2 hr −1) compared to the intact PSF (4.0 ± 2.0 mg CH 4 m −2 hr −1) due to prolonged higher WT and more optimal methanogenesis conditions. On the other hand, we did not find significant differences in R eco between burnt (432 ± 83 mg CO 2 m −2 hr −1) and intact PSF (359 ± 76 mg CO 2 m −2 hr −1). Radiocarbon analysis showed overall no significant difference between intact and burnt PSF with a modern signature for both CO 2 and CH 4 fluxes implying a microbial preference for the more labile C fraction in the peat matrix.

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Section: Discussionsupporting

confidence: 81%

Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH₄ flux

Lupascu

Akhtar

Smith

et al. 2020

Global Change Biology

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“…2a). High methanotroph abundance would also imply large CH 4 production, which has previously been reported from both in situ and ex situ studies of CH 4 production/ fluxes (Girkin et al 2018b;Girkin et al, 2018;Sjögersten et al 2011).…”

Section: Peat Botanical Origin and Microbial Community Structuresupporting

confidence: 61%

“…Redox potential is also closely linked to soil moisture content, as waterlogged soils are low in oxygen, except for inputs derived from root oxygen loss and atmospheric diffusion at the surface boundary (Hoyos-Santillan et al 2016a). Plant root inputs of carbon (root exudates) are also able to directly influence peat properties, and may therefore also exert an indirect control on microbial community structure and function, but the precise effect is dependent on the composition and concentration of the input (Girkin et al 2018b). Moreover, peat properties are also strongly linked to the properties and quantity of leaf, root and shoot inputs and the influence of their decomposition products on their immediate environment (Hoyos-Santillan et al 2015).…”

Section: Environmental Regulation Of Microbial Community Structurementioning

confidence: 99%

Peat Properties, Dominant Vegetation Type and Microbial Community Structure in a Tropical Peatland

et al. 2020

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Tropical peatlands are an important carbon store and source of greenhouse gases, but the microbial component, particularly community structure, remains poorly understood. While microbial communities vary between tropical peatland land uses, and with biogeochemical gradients, it is unclear if their structure varies at smaller spatial scales as has been established for a variety of peat properties. We assessed the abundances of PLFAs and GDGTs, two membrane spanning lipid biomarkers in bacteria and fungi, and bacteria and archaea, respectively, to characterise peat microbial communities under two dominant and contrasting plant species, Campnosperma panamensis (a broadleaved evergreen tree), and Raphia taedigera (a canopy palm), in a Panamanian tropical peatland. The plant communities supported similar microbial communities dominated by Gram negative bacteria (38.9-39.8%), with smaller but significant fungal and archaeal communities. The abundance of specific microbial groups, as well as the ratio of caldarchaeol:crenarchaeol, isoGDGT: brGDGTs and fungi:bacteria were linearly related to gravimetric moisture content, redox potential, pH and organic matter content indicating their role in regulating microbial community structure. These results suggest that tropical peatlands can exhibit significant variability in microbial community abundance even at small spatial scales, driven by both peat botanical origin and localised differences in specific peat properties.

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“…Declines in root biomass might have been expected to be associated with lower root-derived CO 2 . Estimates of root respiration in tropical sites are variable, accounting for up to two-thirds of total CO 2 flux from forested peatlands in Malaysia and Panama (Melling et al 2013; Girkin et al 2018c), but varying from 24 to 61% in Amazon forests (Silver et al 2005; Metcalfe et al 2007). CO 2 emissions can also be driven by microbial utilisation of root exudates and peat organic matter, and the oxidation of CH 4 (Wright et al 2013a).…”

Section: Discussionmentioning

confidence: 99%

Spatial variability of organic matter properties determines methane fluxes in a tropical forested peatland

et al. 2018

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Tropical peatland ecosystems are a significant component of the global carbon cycle and feature a range of distinct vegetation types, but the extent of links between contrasting plant species, peat biogeochemistry and greenhouse gas fluxes remains unclear. Here we assessed how vegetation affects small scale variation of tropical peatland carbon dynamics by quantifying in situ greenhouse gas emissions over 1 month using the closed chamber technique, and peat organic matter properties using Rock-Eval 6 pyrolysis within the rooting zones of canopy palms and broadleaved evergreen trees. Mean methane fluxes ranged from 0.56 to 1.2 mg m −2 h −1 and were significantly greater closer to plant stems. In addition, pH, ranging from 3.95 to 4.16, was significantly greater closer to stems. A three pool model of organic matter thermal stability (labile, intermediate and passive pools) indicated a large labile pool in surface peat (35–42%), with equivalent carbon stocks of 2236–3065 g m −2 . Methane fluxes were driven by overall substrate availability rather than any specific carbon pool. No peat properties correlated with carbon dioxide fluxes, suggesting a significant role for root respiration, aerobic decomposition and/or methane oxidation. These results demonstrate how vegetation type and inputs, and peat organic matter properties are important determinants of small scale spatial variation of methane fluxes in tropical peatlands that are affected by climate and land use change. Electronic supplementary material The online version of this article (10.1007/s10533-018-0531-1) contains supplementary material, which is available to authorized users.

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Root-derived CO2 flux from a tropical peatland

Cited by 16 publications

References 41 publications

Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH₄ flux

Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH₄ flux

Peat Properties, Dominant Vegetation Type and Microbial Community Structure in a Tropical Peatland

Spatial variability of organic matter properties determines methane fluxes in a tropical forested peatland

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Root-derived CO2 flux from a tropical peatland

Cited by 16 publications

References 41 publications

Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH4 flux

Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH4 flux

Peat Properties, Dominant Vegetation Type and Microbial Community Structure in a Tropical Peatland

Spatial variability of organic matter properties determines methane fluxes in a tropical forested peatland

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Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH₄ flux

Post‐fire carbon dynamics in the tropical peat swamp forests of Brunei reveal long‐term elevated CH₄ flux