Nighttime doesn’t stop N2O and CH4 exchange from riparian forest tree stems with the atmosphere

0544628 - ÚVGZ 2022 DE eng A - Abstract
Schindler, Thomas - Macháčová, Kateřina - Mander, Ülo - Soosaar, Kaido
Nighttime doesn’t stop N2O and CH4 exchange from riparian forest tree stems with the atmosphere.
EGU General Assembly 2020. on line: European Geosciences Union, 2020.
[EGU General Assembly 2020. 04.05.2020-08.05.2020, online]
R&D Projects: GA ČR(CZ) GJ17-18112Y; GA MŠMT(CZ) LO1415
Institutional support: RVO:86652079
Keywords : methane * nitrous oxide * riparian forest * tree stem * emission * flux * dirunal pattern
OECD category: Plant sciences, botany
https://www.egu2020.eu/

R iparian forest ecosystems have been considered to be a natural source of nitrous oxide (N2O) and a natural sink of methane (CH4). Wetland trees may also contribute to the greenhouse gas (GHG) exchange by the release of both gases to the atmosphere or uptake therefrom. Knowledge about the short-termed day and night-time distributed GHG exchange of tree stems with the atmosphere is still scarce. We studied stem fluxes in a riparian forest ecosystem aiming to investigate the diurnal pattern and predict the potential influence of solar radiation. The diurnal flux measurements were performed at 40-year-old grey alder (Alnus incana) forest stand in Estonia with 12-hour interval during July-September 2017 and May-September 2018 (n=16). The exchange of N2O and CH4 was measured from 12 trees at profile height up to 5 m (0.1, 0.8, 1.7, 2.5, 5.0 m) using non-steady state stem chamber systems and gas chromatography. Simultaneously, soil fluxes were automatically quantified using a dynamic chamber system (Picarro 2508). Our preliminary results showed N2O and CH4 emissions from alder tree stems during daytime (4.91 ± 0.15 μg m-2 h-1 and 66.38 ± 16.02 μg m-2 h-1, mean ± s.e.) and lower during nighttime (3.65 ± 0.22 μg m-2 h-1 and 51.49 ± 13.83 μg m-2 h-1, mean ± s.e.) at 0.1 m stem height, revealing a likely link to solar-driven physiological tree activity. Further, with increasing stem height, the relation of night to daytime fluxes diminished. However, the day-wise variation, including a minor GHG uptake indicates a fast response to changing micro-spatial environmental conditions like water regime in the soil and temperature. Our study demonstrates the GHG exchange between tree stems and atmosphere occurs both in day- and night-time.
Permanent Link: http://hdl.handle.net/11104/0321465