Greenhouse gas dynamics in drained peatlands: CH4 and N2O fluxes from tree stems and soil

0544692 - ÚVGZ 2022 DE eng A - Abstract
Ranniku, R. - Schindler, Thomas - Lehtme, E. - Mander, Ülo - Macháčová, Kateřina - Soosaar, Kaido
Greenhouse gas dynamics in drained peatlands: CH4 and N2O fluxes from tree stems and soil.
EGU General Assembly 2021 (vEGU21: Gather Online). Göttingen: European Geosciences Union, 2021.
[EGU General Assembly Conference 2021. 19.04.2021-30.04.2021, online]
Institutional support: RVO:86652079
Keywords : methane * nitrous oxide * tree stem * forest floor * soil * birch * spruce * chamber
OECD category: Plant sciences, botany
https://www.egu21.eu/

Peatland soils are considered the dominating source of nitrous oxide (N2O) and methane (CH4) to the atmosphere. However, there are high spatio-temporal uncertainties regarding the budgets of these greenhouse gases (GHG) from peatlands due to complex dynamics between the chemical, physical and biological variables occurring in the soil. GHG fluxes from peatland soils are relatively well studied, however, tree stems have received far less attention and are often overlooked in GHG models and assessments. Our ongoing project focuses on measuring GHGs from tree stems and soil in the Agali Birch Forest Research Station in Estonia, representing a drained peatland with Downy Birch (Betula pubescens) and Norway Spruce (Picea abies) trees. Twelve representative sub-sites were selected in the study area. One half consist of an adjacent set of a Birch and a Spruce tree with manual tree stem chambers, plus one automatic dynamic soil chamber. The remaining subsites are set pairs of birch trees and soil chambers. Six birch trees and all six spruce trees have stem chambers installed at 10, 80 and 170 cm above the ground to measure stem fluxes' vertical profile. Chambers on the six remaining birch trees were only installed at the lowest height. During the weekly sampling campaigns that started in October 2020, we use manual static gas extraction from rigid stem chambers to analyse hourly changes in chamber headspace gas concentrations using gas chromatography. Automated soil chambers collect CH4 and N2O flux data every two hours per chamber using a Picarro analyser. When extrapolated, our results can help understand stem and soil GHG emissions on an ecosystem level and acknowledge the role of tree stems for local and regional GHG budgets. We plan to continue our measurements for one full year to understand the seasonal changes in CH4 and N2O emissions patterns.
Permanent Link: http://hdl.handle.net/11104/0321520