EGU22-2574
https://doi.org/10.5194/egusphere-egu22-2574
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Species-specific effects of vascular plants on methane transport in northern peatlands

Mengyu Ge1, Markku Koskinen1,2, Aino Korrensalo6, Päivi Mäkiranta3, Annalea Lohila4, and Mari Pihlatie1,2,5
Mengyu Ge et al.
  • 1Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
  • 2INAR Institute of Institute for Atmospheric and Earth System Research / Forest Sciences, University of Helsinki, Helsinki, Finland
  • 3Natural Resources Institute Finland, Helsinki, Finland
  • 4Finnish Meteorological Institute, Helsinki, Finland
  • 5Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
  • 6School of Forest Sciences, University of Eastern Finland, Joensuu, Finland

Recent studies have identified the significant role of plants in controlling methane (CH4) emission from peatlands by acting as conduits and further demonstrated that such conduit effect is species-specific. In most studies, species-specific plant-mediated CH4 transport has been estimated indirectly by comparing CH4 flux from surfaces with different plant communities to that from surfaces where plants responsible for CH4 transport are cut, known as the clipping technique. However, the estimation based on the clipping technique has shown large uncertainty due to the plant residual effect. Thus, directly investigating the variation in CH4 transport between different plant species and the factors affecting it is necessary to more precisely assess changes in the CH4 fluxes of peatland ecosystems in a changing environment.

We measured CH4 emission directly from shoots of Carex rostrata, Menyanthes trifoliata, Betula nana, and Salix lapponum from the early growing season until the beginning of senescence (June-September 2020 and 2021, three campaigns both years), with three specimens per species and campaign. We also measured CH4 emission from Equisetum fluviatile and Comarum palustre during high summer in 2021 to further shed light on species-specific characteristics of plant-mediated CH4 flux. We monitored abiotic factors such as belowground CH4 concentration, potential CH4 production and oxidation rate, water table level, and peat temperature.

During high summer in 2021, C. rostrata had the highest CH4 transport rate per leaf area (6.86 mg m-2 h-1). This value was significantly higher than that from M. trifoliata which was the secondarily important CH4 emitter with the rate of 4.07 mg m-2 h-1. E. fluviatile, C. palustre, B. nana, and S. lapponum had limited CH4 transport rate per leaf area (0.66, 0.02, 0.14, and 0.15 mg m-2 h-1, respectively) and thus were negligible CH4 emitters. CH4 emission from C. rostrata demonstrated the most pronounced seasonal variation (ranging from 0.02 to 24.78 mg m-2 h-1), driven primarily by seasonal vegetation development (phenology) and only secondarily by rhizospheric peat temperature. In contrast, CH4 emission from M. trifoliata, B. nana, and S. lapponum showed little seasonal variation, and no factors that significantly affected the flux from these species were found. Lastly, the sharp decrease in rhizospheric peat CH4 concentration during high summer and the simultaneous increase in emission from C. rostrata, the most dominant species in our site, indicated the conduit effect predominated over the CH4 production and oxidation. The findings highlight the importance of C. rostrata in mediating CH4, which could exacerbate the climatic impact of the thawing permafrost region where C. rostrata can thrive in wet microsites.

How to cite: Ge, M., Koskinen, M., Korrensalo, A., Mäkiranta, P., Lohila, A., and Pihlatie, M.: Species-specific effects of vascular plants on methane transport in northern peatlands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2574, https://doi.org/10.5194/egusphere-egu22-2574, 2022.

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