Physiological processes affecting methane transport by wetland vegetation – A review

Vroom, Renske; Berg, Merit van den; Pangala, Sunitha Rao; Scheer, O.E. van der; Sorrell, Brian K.

doi:10.1016/j.aquabot.2022.103547

Cited by 47 publications

(33 citation statements)

References 172 publications

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“…quinquenervia tree stems contributed ∼27.8% – 68.3% of the NEF from the Lower and Transitional zones of the wetland respectively (Figure 11). This study provides clear evidence that tree stems are a significant and often missing component of many previous wetland CH 4 budgets, where they have been largely overlooked (Barba et al., 2019a; Bastviken et al., 2023; Covey & Megonigal, 2019; Vroom et al., 2022). The CH 4 flux rates and upscaled rates from the subtropical M .…”

Section: Discussionmentioning

confidence: 70%

Large Methane Emissions From Tree Stems Complicate the Wetland Methane Budget

Jeffrey,

Moras,

Tait

et al. 2023

JGR Biogeosciences

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Our understanding of tree stem methane (CH4) emissions is evolving rapidly. Few studies have combined seasonal measurements of soil, water and tree stem CH4 emissions from forested wetlands, inhibiting our capacity to constrain the tree stem CH4 flux contribution to the total wetland CH4 flux. Here we present annual data from a subtropical freshwater Melaleuca quinquenervia wetland forest, spanning an elevational topo‐gradient (Lower, Transitional and Upper zones). Eight field campaigns captured an annual hydrological flood‐dry‐flood cycle, measuring stem fluxes on 30 trees, from four stem heights, and up to 30 adjacent soil or water CH4 fluxes per campaign. Tree stem CH4 fluxes ranged several orders of magnitude between hydrological seasons and topo‐gradient zones, spanning from small CH4 uptake to an emission of ∼203 mmol m−2 d−1. Soil CH4 fluxes were similarly dynamic and shifted from CH4 emission (saturated soil) to uptake (dry soil). In Lower and Transitional zones respectively, tree stem CH4 contribution to the net CH4 ecosystem flux was greatest during flooded conditions (49.9% and 70.2%) but less important during dry periods (3.1% and 28.2%). Minor tree stem emissions from the Upper elevation zone still offset the Upper zone CH4 soil sink capacity by ∼51% during dry conditions. Water table height was the strongest driver of tree stem CH4 fluxes, however tree emissions peaked once the soil was inundated and did not increase with further water depth. This study highlights the importance of quantifying the wetland tree stem CH4 emissions pathway as an important and seasonally oscillating component of wetland CH4 budgets.

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Section: Discussionmentioning

confidence: 70%

Large Methane Emissions From Tree Stems Complicate the Wetland Methane Budget

Jeffrey,

Moras,

Tait

et al. 2023

JGR Biogeosciences

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“…Such a strategy may also favour biodiversity and comes with well-documented direct and indirect environmental benefits, including higher pollination success, greater ecosystem functioning, better resilience to pests, and improved aesthetic value 24,26 . Yet, using plants to reduce nutrients in water bodies could come at the cost of reducing runoff to a dam, and increasing input of organic carbon (plant material) to fuel decomposition and GHG production 27,28 . More studies are required to understand the trade-offs of using phytoremediation for water security and GHG emissions.…”

Section: Discussionmentioning

confidence: 99%

Methane emissions from agricultural ponds are underestimated in national greenhouse gas inventories

Malerba

Kluyver²,

Wright³

et al. 2022

Commun Earth Environ

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Agricultural ponds have some of the highest methane emissions per area among freshwater systems, and these anthropogenic emissions should be included in national greenhouse gas inventories. Here we deliver a continental-scale assessment of methane emissions from agricultural ponds in the United States and Australia. We source maps of agricultural ponds, compile a meta-analysis for their emissions and use published data to correct for temperature and the relative contributions of two methane fluxes (diffusion and ebullition). In the United States, 2.56 million agricultural ponds cover 420.9 kha and emit about 95.8 kt year−1 of methane. In Australia, 1.76 million agricultural ponds cover 291.2 kha and emit about 75.1 kt year−1 of methane. Despite large uncertainties, our findings suggest that small water bodies emit twice as much methane than is currently accounted for in national inventories. Managing these systems can reduce these emissions while benefiting productivity, ecosystem services, and biodiversity.

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“…While Fe cycling occurs in saline wetlands (Hyun et al, 2007), methanogenesis is suppressed primarily by sulfate (SO 2− 4 ) as the dominant electron acceptor (Howarth & Giblin, 1983;King & Wiebe, 1980;Klepac-Ceraj et al, 2004;Laanbroek, 2010), limiting the use of Fe(III) plaque as a trait in saline wetlands. Furthermore, Vroom et al (2022) suggest that Fe(III) plaque could theoretically act as a barrier for CH 4 transport but this remains to be investigated. Fe(III) plaque is a useful proxy for separating the effects of root-mediated C (i.e., electron donor) provision and rhizosphere oxygenation (i.e., electron acceptor provision) on CH 4 production, a separation which is often neglected (Sutton-Grier & Megonigal, 2011).…”

Section: Gas Transportmentioning

confidence: 99%

The hidden roots of wetland methane emissions

Määttä,

Malhotra

2024

Global Change Biology

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Wetlands are the largest natural source of methane (CH4) globally. Climate and land use change are expected to alter CH4 emissions but current and future wetland CH4 budgets remain uncertain. One important predictor of wetland CH4 flux, plants, play an important role in providing substrates for CH4‐producing microbes, increasing CH4 consumption by oxygenating the rhizosphere, and transporting CH4 from soils to the atmosphere. Yet, there remain various mechanistic knowledge gaps regarding the extent to which plant root systems and their traits influence wetland CH4 emissions. Here, we present a novel conceptual framework of the relationships between a range of root traits and CH4 processes in wetlands. Based on a literature review, we propose four main CH4‐relevant categories of root function: gas transport, carbon substrate provision, physicochemical influences and root system architecture. Within these categories, we discuss how individual root traits influence CH4 production, consumption, and transport (PCT). Our findings reveal knowledge gaps concerning trait functions in physicochemical influences, and the role of mycorrhizae and temporal root dynamics in PCT. We also identify priority research needs such as integrating trait measurements from different root function categories, measuring root‐CH4 linkages along environmental gradients, and following standardized root ecology protocols and vocabularies. Thus, our conceptual framework identifies relevant belowground plant traits that will help improve wetland CH4 predictions and reduce uncertainties in current and future wetland CH4 budgets.

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Physiological processes affecting methane transport by wetland vegetation – A review

Cited by 47 publications

References 172 publications

Large Methane Emissions From Tree Stems Complicate the Wetland Methane Budget

Large Methane Emissions From Tree Stems Complicate the Wetland Methane Budget

Methane emissions from agricultural ponds are underestimated in national greenhouse gas inventories

The hidden roots of wetland methane emissions

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