EGU22-11926, updated on 28 Mar 2022
https://doi.org/10.5194/egusphere-egu22-11926
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Greenhouse gas fluxes from nutrient-rich organic soils in Estonia

Muhammad Kamil Sardar Ali1, Thomas Schindler1,2, Ain Kull1, Hanna Vahter1, Ülo Mander1, and Kaido Soosaar1,2
Muhammad Kamil Sardar Ali et al.
  • 1Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, 46 Vanemuise, EST-51014 Tartu, Estonia
  • 2Department of Ecosystem Trace Gas Exchange, Global Change Research Institute of the Czech Academy of Sciences, Belidla 4a, CZ-60300 Brno, Czech Republic *Email: kamil.sardar@ut.ee

Nutrient-rich organic soils are one of the largest key sources of greenhouse gas (GHG) emissions in cool moist climate regions in Europe, and around 15 Mha of wetlands are drained for forestry across the world's temperate and boreal areas. Drainage promotes the decomposition of the organic material stored in these naturally water-saturated organic soils, turning the wetland from a carbon sink into an emitter of CO2. Lower soil water content in drained histosols leads to reduced CH4 emission, while N2O emission can increase due to increased mineralization and more favorable conditions for nitrification. However, detailed information of GHG emissions from drained organic soils under different land use and management in the hemiboreal zone is still scarce.  

We conducted a full-year study at drained peatland sites with different land uses to assess the impact of drainage and land-use on GHG fluxes in Estonia. We investigated ten sites: (I) five forests with different tree species, (II) three grasslands with different water regimes, (III) cropland and (IV) natural wetland (fen). The GHG fluxes were measured twice per month using the manual static (CH4 and N2O) and dynamic (heterotrophic respiration (CO2)) closed chamber method from Jan 2020 to Dec 2021. Additionally, groundwater level, soil temperature and moisture were measured hourly with automatic loggers to determine soil conditions.   

Our preliminary results show that all drained forest soils were annual CH4 sinks (−59.4 ± 2.5 µg m-2 h-1, mean ± SE). However, CH4 uptake from the studied fen, crop and grasslands were lower, –13.2 ± 4.4, -12.2 ± 2.0 and -8.2 ± 3.3 µg m-2 h-1, respectively, while grassland with poor drainage soil was a less source of CH4 emission. Most of the sites were annual emitters of N2O; forest sites were higher emitters (15.9 ± 2.3 µg m-2 h-1) than cropland (12.7 ± 4.1 µg m-2 h-1) and fen soils (6.3 ± 1.1 µg m-2 h-1). N2O fluxes from grasslands depend on drainage intensity and the site with poor drainage emitted less. Higher N2O emissions and temporal variability were associated with sites where the water level had high seasonal fluctuations. Soil CO2 fluxes (heterotrophic respiration) were highest from grasslands and peaked over all the study sites during the summer. Methane flux had a statistically significant correlation with water level and soil moisture, while N2O flux was controlled by soil temperature, having higher emissions in a warmer season. The results provide insights into GHG fluxes over temporal and spatial scales and indicate the need for mitigation measures and further enhancement of modeling tools for climate-friendly land management practices in nutrient-rich organic soils.   

This research was supported by the LIFE programme project “Demonstration of climate change mitigation potential of nutrients rich organic soils in Baltic States and Finland”, (2019-2023, LIFE OrgBalt, LIFE18 274CCM/LV/001158) 

How to cite: Sardar Ali, M. K., Schindler, T., Kull, A., Vahter, H., Mander, Ü., and Soosaar, K.: Greenhouse gas fluxes from nutrient-rich organic soils in Estonia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11926, https://doi.org/10.5194/egusphere-egu22-11926, 2022.

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