Radiation and temperature drive diurnal variation of aerobic methane emissions from Scots pine canopy

Kohl, Lukas ORCID: https://orcid.org/0000-0002-5902-9444 , Tenhovirta, Salla A.M. ORCID: https://orcid.org/0000-0001-5600-6274 , Koskinen, Markku ORCID: https://orcid.org/0000-0002-9473-6064 , Putkinen, Anuliina, Haikarainen, Iikka, Polvinen, Tatu, Galeotti, Luca, Mammarella, Ivan, Siljanen, Henri M.P. ORCID: https://orcid.org/0000-0002-3197-1438 , Robson, Matthew ORCID: https://orcid.org/0000-0002-8631-796X , Adamczyk, Bartosz and Pihlatie, Mari ORCID: https://orcid.org/0000-0001-6035-3949 (2023) Radiation and temperature drive diurnal variation of aerobic methane emissions from Scots pine canopy. Proceedings of the National Academy of Sciences, 120 (52).

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Abstract

Methane emissions from plant foliage may play an important role in the global methane cycle, but their size and the underlying source processes remain poorly understood. Here, we quantify methane fluxes from the shoots of Scots pine trees, a dominant tree species in boreal forests, to identify source processes and environmental drivers, and we evaluate whether these fluxes can be constrained at the ecosystem-level by eddy covariance flux measurements. We show that shoot-level measurements conducted in forest, garden, or greenhouse settings; on mature trees and saplings; manually and with an automated CO 2 -, temperature-, and water-controlled chamber system; and with multiple methane analyzers all resulted in comparable daytime fluxes (0.144 ± 0.019 to 0.375 ± 0.074 nmol CH 4 g −1 foliar d.w. h −1 ). We further find that these emissions exhibit a pronounced diurnal cycle that closely follows photosynthetically active radiation and is further modulated by temperature. These diurnal patterns indicate that methane production is associated with diurnal cycle of sunlight, indicating that this production is either a byproduct of photosynthesis-associated biochemical reactions (e.g., the methionine cycle) or produced through nonenzymatic photochemical reactions in plant biomass. Moreover, we identified a light-dependent component in stand-level methane fluxes, which showed order-of-magnitude agreement with shoot-level measurements (0.968 ± 0.031 nmol CH 4 g −1 h −1 ) and which provides an upper limit for shoot methane emissions.

Item Type:	Article
Journal / Publication Title:	Proceedings of the National Academy of Sciences
Publisher:	National Academy of Sciences
ISSN:	1091-6490
Departments:	Institute of Science and Environment > Forestry and Conservation
Additional Information:	Thomas Matthew Robson, National School of Forestry, University of Cumbria. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY).
Depositing User:	Insight Administrator
SWORD Depositor:	Insight Administrator
Date Deposited:	04 Jan 2024 13:35
Last Modified:	13 Jan 2024 16:00
URI:	https://insight.cumbria.ac.uk/id/eprint/7504

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