EGU22-4184
https://doi.org/10.5194/egusphere-egu22-4184
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Impacts of continuous cover forestry and clear-cutting on water quality and the biodegradability of dissolved organic carbon in a drained boreal peatland 

Marjo Palviainen1, Elina Peltomaa1, Annamari (Ari) Laurén2, Niko Kinnunen3, Anne Ojala4, Frank Berninger5, Xudan Zhu5, and Jukka Pumpanen3
Marjo Palviainen et al.
  • 1University of Helsinki, Department of Forest Sciences, Helsinki, Finland (marjo.palviainen@helsinki.fi)
  • 2Faculty of Science and Forestry, University of Eastern Finland, Joensuu, Finland
  • 3Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
  • 4Natural Resources Institute Finland, Finland
  • 5Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland

Boreal peatlands are major sources of nitrogen (N), phosphorus (P) and dissolved organic carbon (DOC) to downstream aquatic ecosystems, and peatland forest harvesting further increases the export of DOC and nutrients. Increased DOC and nutrient loading affects biogeochemical processes and food webs of surface waters, and may cause eutrophication and hypoxia. Furthermore, lateral carbon (C) flux from terrestrial to aquatic ecosystems is an important but often ignored component of the global C cycle, because DOC mineralization to CO2 in inland waters markedly contributes to the total C emissions to the atmosphere. Continuous cover forestry (CCF) is proposed to be an environmentally more sustainable management option for peatland forests than clear-cutting. However, the environmental effects of CCF are poorly known. We studied ground water and ditch water N, P and DOC concentrations in clear-cut, partially harvested, i.e. CCF, and uncut drained peatland forests in Finland. We also investigated the effects of harvesting intensity on DOC quality and DOC biodegradation to CO2. Groundwater nutrient and DOC concentrations were lower in CCF and uncut forest than in the clear-cut forest. Groundwater DOC aromaticity was higher in the uncut forest than in the clear-cut and CCF, whereas ditch water aromaticity did not differ between the treatments. The biodegradation of DOC was studied by incubating water (at 15 °C for 24 h) 1, 3, 7 and 21 days after the sampling. The results indicated that the majority of the CO2 production took place during the first three days, and CO2 fluxes were considerably higher from the ditch water than from the groundwater. Biodegradability of DOC was lower in summer than in the other seasons. Ditch water and groundwater CO2 production were generally significantly higher in the clear-cut than in the uncut forest. The results suggest that partial harvesting used in CCF reduces DOC and nutrient concentrations in watercourses, decreases DOC biodegradability, and therefore the aquatic CO2 emissions compared to clear-cutting in drained peatland forests. Thus, CCF can cause less environmental drawbacks than the conventional clear-cutting.

How to cite: Palviainen, M., Peltomaa, E., Laurén, A. (., Kinnunen, N., Ojala, A., Berninger, F., Zhu, X., and Pumpanen, J.: Impacts of continuous cover forestry and clear-cutting on water quality and the biodegradability of dissolved organic carbon in a drained boreal peatland , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4184, https://doi.org/10.5194/egusphere-egu22-4184, 2022.