Plant root exudates increase methane emissions through direct and indirect pathways

Waldo, Nicholas B.; Hunt, Brianna K.; Fadely, Eleanor C.; Moran, James J.; Neumann, Rebecca B.

doi:10.1007/s10533-019-00600-6

Cited by 61 publications

(55 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Through combined measurements of dissolved porewater CH 4 and CH 4 flux rates, our study revealed potentially significant mechanisms in plant‐mediated CH 4 flux. Low porewater CH 4 concentrations below plants was somewhat unexpected, as vegetation is known to supply fresh carbon substrates (i.e., root exudates) to fuel methanogenic CH 4 production (Christensen et al, 2003; King & Reeburgh, 2002; Knorr et al, 2008; Waldo et al, 2019). On the other hand, root oxygenation can increase CH 4 oxidation (Conrad, 2009; Faußer et al, 2012; Jeffrey, Maher, Johnston, Maguire, et al, 2019; Laanbroek, 2010) or alter availability of redox‐active substrates (i.e., Fe (OH) 3 ) to favor nonmethanogenic microbial respiration (i.e., reduction of Fe (OH) 3 to Fe +2 ; Roden & Wetzel, 1996; Neubauer et al, 2007), both of which would result in lower porewater CH 4 below plants.…”

Section: Discussionmentioning

confidence: 99%

“…During drying, there is consumption of labile carbon substrates by aerobic respiration, regeneration of alternate electron acceptors, reduction in size of methanogenic communities, and increased CH 4 oxidation, all of which delay recovery of CH 4 emissions by days to months following rewetting (Boon et al, 1997; Conlin & Crowder, 1989; Kim et al, 2012; Knorr et al, 2008; Sundh et al, 1994; Tian et al, 2012). Vegetation can speed up the rate of recovery by priming microbial activity via fresh carbon substrates (Ström et al, 2005; Waldo et al, 2019) but can also delay recovery by supplying O 2 for methanotrophic communities (Faußer et al, 2012) and by extending dry conditions through transpiration. In our study, O 2 levels were minimal in all treatments following rewetting, and none of the treatments exhibited high CH 4 flux rates or accumulated a porewater CH 4 reserve after 3 months.…”

Section: Discussionmentioning

confidence: 99%

“…Saturated soils were passed through a 6‐mm sieve to remove coarse vegetation and debris and homogenized. We assumed that any low‐molecular‐weight, labile carbon substrates from previous plant exudates were consumed before soil was distributed in mesocosms; however, nonlabile C likely remained (Waldo et al, 2019). Each mesocosm was filled with uniform soil to a depth of 10 cm.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Vegetation Affects Timing and Location of Wetland Methane Emissions

et al. 2020

View full text Add to dashboard Cite

Common assumptions about how vegetation affects wetland methane (CH 4) flux include acting as conduits for CH 4 release, providing carbon substrates for growth and activity of methanogenic organisms, and supplying oxygen to support CH 4 oxidation. However, these effects may change through time, especially in seasonal wetlands that experience drying and rewetting, or change across space, dependent on proximity to vegetation. In a mesocosm study, we assessed the impacts of Typha on CH 4 flux using clear flux chamber measurements directly over Typha plants ("whole-plant"), adjacent to Typha plants (where roots were present but no stems; "plant-adjacent"), and plant-free soils ("control"). During the establishment phase of the study (first 30 days), the whole-plant treatment had~5 times higher CH 4 flux rates (51.78 ± 8.16 mg-C m −2 day −1) than plant-adjacent or control treatments, which was primarily due to plant-mediated transport, with little contribution from diffusive-only flux. However, porewater CH 4 concentrations were relatively low directly below whole-plant and in neighboring plant-adjacent treatments, while controls accumulated a highly concentrated reservoir of porewater CH 4. When the water table was drawn down to simulate seasonal drying, reserve porewater CH 4 from control soil was released as a pulse, equaling the earlier higher CH 4 emissions from whole-plants. Plant-adjacent treatments, which had neither plant-mediated CH 4 transport nor a concentrated reservoir of porewater CH 4 , had low CH 4 flux throughout the study. Our findings indicate that in seasonal wetlands, vegetation affects the timing and location of CH 4 emissions. These results have important mechanistic and methodological implications for understanding the role of vegetation on wetland CH 4 flux.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Vegetation Affects Timing and Location of Wetland Methane Emissions

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Roots and rhizomes in wetland ecosystems influence methane-related substrates through at least two mechanisms: (i) deposition of organic compounds that support multiple pathways of heterotrophic microbial respiration, including methanogenesis, and (ii) release of O2 that simultaneously promotes CH4 oxidation (Philippot et al, 2009;Stanley & Ward, 2010) and regeneration of competing electron acceptors such as Fe(III) and SO4. Root exudates, which typically include low molecular weight compounds, may either be more readily used by microbes than existing soil C (Kayranli et al, 2010;Megonigal et al, 1999) or may prime microbial use of soil C (Basiliko et al, 2012;Philippot et al, 2009;Robroek et al, 2016;Waldo et al, 2019). Root exudates can also decrease CH4 oxidation by stimulating use of O2 by other aerobic microbes (Lenzewski et al, 2018;Mueller et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Although it is understood that wetland plants are a primary control on CH4 emissions and that much of their influence is mediated through conditions in the rhizosphere (Waldo et al, 2019), there are surprisingly few data, especially from coastal wetlands, that couple plant responses to the dynamics of electron donors (organic C), electron acceptors (O2, SO4), and the rates of competing (sulfate reduction vs methanogenesis) or opposing (CH4 production vs CH4 oxidation) microbial processes. The general lack of process data on wetland CH4 cycling makes it difficult to forecast ecosystem responses to climate change.…”

Section: Introductionmentioning

confidence: 99%

Biogeochemical and plant trait mechanisms drive enhanced methane emissions in response to whole-ecosystem warming

Noyce¹,

Megonigal²

2020

Preprint

View full text Add to dashboard Cite

Abstract. Climate warming perturbs ecosystem carbon (C) cycling, causing both positive and negative feedbacks on greenhouse gas emissions. In 2016, we began a tidal marsh field experiment in two vegetation communities to investigate the mechanisms by which whole-ecosystem warming alters C gain, via plant-driven sequestration in soils, and C loss, primarily via methane (CH4) emissions. Here, we report the results from the first four years. As expected, warming of 5.1 °C more than doubled CH4 emissions in both plant communities. We propose this was caused by a combination of four mechanisms: (i) a decrease in the proportion of CH4 consumed by CH4 oxidation, (ii) more C substrates available for methanogenesis, (iii) reduced competition between methanogens and sulfate reducing bacteria, and (iv) indirect effects of plant traits. Plots dominated by Spartina patens consistently emitted more CH4 than plots dominated by Schoenoplectus americanus, indicating key differences in the roles these common wetland plants play in affecting anerobic soil biogeochemistry and suggesting that plant composition can modulate coastal wetland responses to climate change.

show abstract

Aerenchyma in emergent plants and rhizospheric microbial communities promote methane fluxes in wetlands

Guo,

Zhang,

et al. 2024

Limnology & Oceanography

View full text Add to dashboard Cite

Wetlands are the largest natural source of CH4 globally, yet our understanding of how environmental parameters and microorganisms affect the production and emission of CH4 in emergent plant–sediment systems remains limited. In this study, CH4 fluxes were investigated in a wetland with Canna indica for 42 d, as well as nutrients and microbial community. It was found that the chimney effect formed by aerenchyma in roots, stems, and leaves of C. indica promoted the emission and oxidation of CH4 in the wetland and reduced the CH4 concentration in sediments. Canna indica reduced the nutrient release from surface sediments into the overlying water. Pearson correlation analysis showed that temperature, pH, and oxidation–reduction potential were the main influencing factors for CH4 production and oxidation in the wetland. Canna indica inhibited the diversity of archaeal community but promoted the diversity of bacterial community in the rhizosphere. Stochastic processes had a greater impact on bacterial and archaeal succession trajectories in wetland sediments. Network analysis showed that C. indica promoted interactions among bacteria and archaea that enhanced their ability to resist environmental interference. The well‐developed aerenchyma of C. indica provided an important passage for the transport of CH4 from sediments to the atmosphere and shaped the microbial community structure in the rhizosphere. Meanwhile, CH4 emissions were also constrained by several variables, such as temperature and physiological adaptation in the long term. Thus, it is necessary to plant emergent plants in areas with low CH4 emissions and optimize plant configuration in the context of global warming.

show abstract

Plant root exudates increase methane emissions through direct and indirect pathways

Cited by 61 publications

References 79 publications

Vegetation Affects Timing and Location of Wetland Methane Emissions

Vegetation Affects Timing and Location of Wetland Methane Emissions

Biogeochemical and plant trait mechanisms drive enhanced methane emissions in response to whole-ecosystem warming

Aerenchyma in emergent plants and rhizospheric microbial communities promote methane fluxes in wetlands

Contact Info

Product

Resources

About