Methanotrophic bacteria in forest soils – should I stay or should I go?
- 1Forest Research Institute Baden-Württemberg (FVA), Wonnhalde 4, 79100 Freiburg, Germany (Verena.Lang@forst.bwl.de)
- 2Department of Crop Sciences, Chair of Soil Physics, University of Göttingen, Grisebachstraße 6, 37077 Göttingen, Germany
Methanotrophic bacteria are capable to uptake methane (CH4) from the atmosphere. They are mainly found in forest soils, making them the most important terrestrial sink for methane. While agricultural soils have partially lost their methane sink function due to the negative effect of nitrogen fertilization on methanotrophy, the methane sink function of forest soils is considered to be intact. Differences in sink capacity of different land use types and short-term factors influencing methane uptake are well studied. Since the most commonly used methodology to measure methane fluxes are energy- and personnel-intensive chamber measurements, there are only few long-term measurements, especially of forest soils. Therefore, little is known about long-term effects and climate change impacts on methane sink function.
In the long-term forest environmental monitoring of the Forest Research Institute (FVA-BW), soil air including methane content has been measured at different depth levels at a monthly interval on 13 forest monitoring plots (ICP Forest Level II) in southwestern Germany for more than 20 years. This method, which is well suited for long-term monitoring, allowed continuous sampling since 1998 and 2010, respectively. From the concentration gradients, the methane flux can be determined using the gradient method. To make these calculated fluxes more precise, chamber measurements were carried out over 1.5 years in 2021/2022 in parallel with the collection of gas samples. By comparing the fluxes of both measurement methods, a validation of the long-term measurement series is possible.
First evaluations of our sites show so far insignificant changes in methane fluxes over the last 20 years. This contrasts our results with study results (Ni & Groffman, 2018), which report a dramatic 53-89% decrease in methane uptake in forest soils observed at four sites in the USA over the last 20 years. Trend estimates of our monitoring sites and the analysis of significant factors influencing long-term methane trends are presented.
References:
Ni, X., Groffman P.M.2018. Declines in methane uptake in forest soils. PNAS 115 (34) 8587-.
How to cite: Lang, V., Hartmann, P., Schengel, A., and Maier, M.: Methanotrophic bacteria in forest soils – should I stay or should I go?, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-17596, https://doi.org/10.5194/egusphere-egu23-17596, 2023.
