Plant mediated methane efflux from a boreal peatland complex

Abstract

Purpose Aerenchymous plants are an important control for methane efflux from peatlands to the atmosphere, providing a bypass from the anoxic peat and avoiding oxidation in the oxic peat. We aimed to quantify the drivers of aerenchymous peatland species methane transport and the importance of this process for ecosystem-scale methane efflux. Methods We measured seasonal and interspecies variation in methane transport rate per gram of plant dry mass at a boreal fen and bog, which were upscaled to ecosystem-scale plant methane transport. Results Methane transport rate was better explained by plant species, leaf greenness and area than by environmental variables. Leaves appeared to transport methane even after senescence. Contrary to our expectations, both methane transport rate and the proportion of plant transport were lower in the fen (with greater sedge cover) than in the bog site. At the fen and bog, average methane transport rate was 0.7 and 1.8 mg g−1 d−1, and the proportion of seasonally variable plant transport was 7–41% and 6–90%, respectively. Species-specific differences in methane transport rate were observed at the ecosystem-scale: Scheuchzeria palustris, which accounted for 16% of the aerenchymous leaf area in the fen and displayed the greatest methane transport rate, was responsible for 45% of the ecosystem-scale plant transport. Conclusion Our study showed that plant species influence the magnitude of ecosystem-scale methane emissions through their properties of methane transport. The identification and quantification of these properties could be the pivotal next step in predicting plant methane transport in peatlands.

Modeled production, oxidation, and transport processes of wetland methane emissions in temperate, boreal, and Arctic regions

“…The contribution of plant‐mediated transport was similar to previous modeling studies because of similar model structure, but tended to be higher than measurements (Table 1). Rhizospheric oxidation (Bansal et al, 2020; Korrensalo et al, 2022) is a potential reason for low CH 4 emissions through vegetation, which was not considered in the current version of iPEACE.…”

“…The transfer efficiency under a given concentration gradient (p plant ; 10 −3 day −1 ) is a calibrated parameter. The model does not consider CH 4 transport by dead plants, which are not accounted for by LAI, with the assumption that collapsed aerenchymatous tissue in senesced leaves has low transport capacity (Korrensalo et al, 2022).…”

“…To improve the mechanistic understanding and accurate modeling of CH 4 emissions, the relative contributions of CH 4 emission pathways have been measured or estimated with various field measurements (Table 1). These measurements include chamber techniques (Korrensalo et al, 2022; Tokida, Miyazaki, et al, 2007; Tokida, Mizoguchi, et al, 2007), bubble traps (Stanley et al, 2019), isotope techniques (Dorodnikov et al, 2011), and dissolved CH 4 concentrations in pore water (McNicol et al, 2017). Recently, a wavelet analysis of EC measurements examined the contribution of ebullition to total CH 4 emissions (Göckede et al, 2019; Iwata et al, 2018; Hwang et al, 2020; Richardson et al, 2022; Schaller et al, 2019).…”

Emissions of methane and other biogenic volatile organic compounds from boreal peatlands

“…While part of methane is known to be oxidized also in some plant species, such as rice (Bosse and Frenzel, 1997), significant methane oxidation in bog plants has not been detected (Frenzel and Rudolph, 1998). Instead, transport of methane through aerenchymatous plants has been shown to have a major contribution to the methane flux rate in boreal peatlands Frenzel and Karofeld, 2000;Korrensalo et al, 2021). In addition to the aerenchymatous leaf area, total leaf area further increase methane emissions in Siikaneva bog (I), which indicates the importance of substrate availability for methane production.…”

Environmental responses of carbon dioxide and methane fluxes of subarctic ecosystems in Northern Finland

“…As CH4 is transported through the plants, the emissions cannot be oxidised by the methanotrophs on the way to the atmosphere. The amount of CH4 plant-mediated emissions of total emissions from boreal peatlands depends on plant species and was observed to vary between 20-35% in bogs and fens (Korrensalo et al, 2022). The contribution of this pathway to the total CH4 emissions has been observed to be larger in fens than bogs, as aerenchymous plants are more common in wet peatlands (Turetsky et al, 2014).…”