Contribution of tree stem and canopy fluxes to the CH4 budget of a boreal birch and spruce forest

0544638 - ÚVGZ 2022 DE eng A - Abstrakt
Pihlatie, M. - Vainio, E. - Haikarainen, I. - Putkinen, A. - Santalahti, M. - Koskinen, M. - Macháčová, Kateřina
Contribution of tree stem and canopy fluxes to the CH4 budget of a boreal birch and spruce forest.
EGU General Assembly 2020. on line: European Geosciences Union, 2020.
[EGU General Assembly 2020. 04.05.2020-08.05.2020, online]
Grant CEP: GA ČR(CZ) GJ17-18112Y; GA MŠMT(CZ) LO1415
Institucionální podpora: RVO:86652079
Klíčová slova: methane * boreal forest * birch * spruce * stem * shoot * soil * flux * methanogens * methanotrophs * leaf-out period * canopy
Obor OECD: Plant sciences, botany
www.egu2020.eu

Upland forest soils are typically a net methane (CH4) sink, while trees may act as CH4 sources. Studies on tree CH4 exchange in boreal forests, especially regarding canopies, are rare. We aimed to quantify the contribution of trees to the forest CH4 budget during spring leaf-out period and to reveal the role of microbes in the CH4 exchange of trees. We measured stem and shoot fluxes of two common boreal tree species at a fen and at an upland site at Hyytiälä, southern Finland, together with soil CH4 flux, environmental variables and the abundances methanogens and methanotrophs within the forest. Both birch (Betula pubescens) and spruce (Picea abies) trees emitted CH4 from their aboveground surfaces, with significantly higher stem emissions detected from the birch and higher shoot emissions from the spruce. The shoot CH4 exchange had no clear link to the vertical profile of the canopy or the progress of the leaf-out. The stem CH4 emissions from birches at the fen were high (mean 45 μg h−1 m−2) and decreased drastically with stem height. Their dynamics followed soil temperature, suggesting the emitted CH4 originated from the soil. A lack of similar pattern in the fen spruces and in the upland birch indicates other processes behind the stem CH4 fluxes of these trees. The lack of detection of methanogens or methanotrophs in the aboveground plant tissues suggest that the observed tree-derived CH4 fluxes were not induced by these microbes. The emitted CH4 from the tree stems may, however, be produced microbially in the soil indicating that physiological differences in tree anatomy or adaptation to different belowground conditions might be a key factor explaining the differences between the tree species.
Trvalý link: http://hdl.handle.net/11104/0321469