Die Bedeutung der borealen Waldökosysteme der Komi Republik für das regionale und europäische Methan-Budget

• Antragstellerin: Dr. Julia Schneider
• Fachliche Zuordnung: Physische Geographie
• Förderung: Förderung von 2012 bis 2018
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 222333738

• Erstellungsjahr: 2017

Zusammenfassung der Projektergebnisse

This study presents first data on CH4 fluxes of the forest-peatland transition zones and clear cuts from boreal European Russia and gives insights into control mechanisms of these ecotones' CH4 emissions which are worldwide underrepresented in the CH4 flux studies. Spatial or temporal forest-peatland transition zones were proposed as potential hot spots of methane (CH4) emissions. However, their role in the regional carbon cycle remained unclear. This study shows that transition zones are characterized by significant lower CH4 emissions compared to open peatlands and are thus not a hot spot for CH4 emissions as was expected in previous studies. Fluxes of CH4 from the transition zone sites showed higher response to soil temperature than to water table level. Fluxes of CH4 between the atmosphere and the two investigated peatlands were not significant different, although a significant difference in water table level could be observed. This is mainly due to the fact that the WTL's of both peatlands were within the optimum for CH4 emissions. The meteorological conditions of the investigated summers changed from being hot and dry in 2013 to cold and wet in 2014; the summer of 2015 was characterized by warmer and drier first half and colder and wetter second half. Significant difference in CH4 fluxes were measured only between 2014 and 2013. Negative fluxes were measured at dry forest sites. It was shown before in Canada and USA that paludification might occur after clear cut of forests. Although clear cut forest area drastically increased in European Russia during the last two decades, if water level depths in these forests remains below 10 cm they do not act as CH4 sources. As the number of years passed after the clear cut as well as the number of investigated sites was small, further work is required to investigate the long-term impact of paludification on CH4 dynamics. Significant differences in CH4 fluxes and in nonlinear regressions showed that the CH4 fluxes of the different site types such as dry forests, transition zones and open peatlands need to be modelled separately on landscape level. Obviously, underlying processes vary with the ecosystem and (along with regional aspects) have to be understood first before large-scale modeling is possible. It is difficult to estimate the area covered by the forest-peatland transition zone at larger scales. In our study, the area of the peatland covered by forest-peatland transition zone varied from 10 % to 34 %. For the investigated peatlands a relationship between the size of the peatland and the area covered by transition zone could not be observed. It seems to be more dependent on topographic constraints, occurrence of forested islands, as well as on climate and development stage of the peatland. The mean annual CH4 emissions of the transition zone are 30 % to 45 % lower than those of open peatland. Most studies on regional CH4 budgets do not implement these new findings into their upscaling efforts and thus, should be changed accordingly. At a rough estimate 5 % to 20 % would have to be subtracted from methane upscales.

Projektbezogene Publikationen (Auswahl)

• 2015. Modeling micro-topographic controls on boreal peatland hydrology and methane fluxes. Biogeosciences, 12
  Cresto Aleina, F., Runkle, B. R. K., Kleinen, T., Kutzbach, L., Schneider, J., Brovkin, V.
  
• 2015. Spatial variation in potential photosynthesis in Northern European bogs. Journal of Vegetation Science
  Laine, A., Wilson, D., Alm, J., Schneider, J., Tuittila, E.-S.
  
• 2016 Russian boreal peatlands dominate the natural European methane budget. Environmental Research Letters 11
  Schneider, J., Jungkunst, H.F., Wolf, U., Schreiber, P., Gažovič, M., Miglovets, M., Mikhaylov, O., Grunwald, D., Erasmi, S., Wilmking, M., Kutzbach, L.
  
• 2016. Annual variability of CO2 and CH4 fluxes from a boreal peatland. In: Zagirova, S., Schneider, J. (Eds.) Ecosystem of a mesooligotrophic peatland in northwestern Russia: development, structure, and function. Syktyvkar, Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences
  Gažovič, M., Kutzbach, L., Forbrich, I., Schneider, J., Wolf, U., Wille, C., Wilmking, M.
  
• 2016. Boreal peatland net ecosystem CO2 exchange – an integrative comparison between fluxes measured by closed chamber and eddy covariance technique. In: Zagirova, S., Schneider, J. (Eds.) Ecosystem of a mesooligotrophic peatland in northwestern Russia: development, structure, and function. Syktyvkar, Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences
  Schneider, J., Gažovič, M., Kutzbach, L., Forbrich, I., Wu, J., Susiluoto, S., Virtanen, T., Wilmking, M.
  
• 2016. Long-term dynamics of methane emission in mesooligotrophic peatland. In: Zagirova, S., Schneider, J. (Eds.) Ecosystem of a mesooligotrophic peatland in northwestern Russia: development, structure, and function. Syktyvkar, Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences
  Miglovets, M., Schreiber, P., Schneider, J., Lukasheva, M.
  
• 2018. Methane emissions from paludified boreal soils in European Russia as measured and modelled. Ecosystems
  Schneider, J., Ťupek, B., Lukasheva, M., Gudyrev, V., Miglovets, M., Jungkunst H. F.