Impact of long-term wetting on carbon cycling and climate change feedback in a northern temperate bog (Ontario, Canada)

• Applicant: Professor Dr. Klaus-Holger Knorr, since 9/2016
• Subject Area: Soil Sciences ; Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 235313194

Northern peatlands represent an important global carbon stock and source of methane to the atmosphere. The fate of carbon in these environments under changed climatic conditions is thus of considerable scientific importance. Our knowledge of future peatland carbon cycling is deficient with respect to the effects of future wetter conditions, both by climate change and by changes in runoff networks surrounding peatlands. We will address this research gap at Luther Bog (Ontario), which represents a northern ombrotropic bog complex that, in one area, has undergone long-term wetter soil conditions. Preliminary work demonstrated that the long-term effects of 60 years of a) winter-wetter and b) winter-wetter and summer-drier soil moisture conditions can be studied against two reference sites of similar water table dynamics, yet different vegetation and soil temperatures. To identify the impact of these relevant climate change scenarios on carbon cycling is the overarching objective of the project. Specifically, we will - establish an atmospheric carbon balance in four areas of differing climate change analogues and quantify the effect on C fluxes, C sequestration and greenhouse warming potentials (GWP) - identify the impact of the changed soil hydrologic regime on in vitro and in situ peat decomposition and the chemical quality of the formed peat- identify changes in the distribution between soil microbial and plant-derived respiration as these are differentially dependent on climatic drivers - determine differences in the temperature dependency soil microbial and plant-derived respiration under background and wetter soil moisture regimeApart from closing an important empirical research deficiency, the project will provide an empirical basis for ecosystem modeling efforts that will generalize the response of peatlands to wetter conditions and allow for the testing of climate change scenarios. The overall hypothesis to be tested is that I) wetter conditions will lead to increased carbon sequestration due to slowing of soil respiration and II) to enhanced methane emissions due to less methane oxidation and establishment of plant communities adapted to wet conditions. We further hypothesize that the effect of additional methane emissions will outweigh that of carbon sequestration on a 100-year time scale. We also expect that more poorly decomposed and highly permeable peat accumulates that has a high potential for CO2 emissions under oxic conditions and a more pronounced seasonal dynamics of carbon fluxes. The aggrading peat masses would thus be much more instable against future changes in hydrologic boundary conditions.

• DFG Programme: Research Grants
• International Connection: Canada
• Participating Persons: Professor Dr. Philippe van Cappellen; Professorin Dr. Claudia Wagner-Riddle
• Ehemaliger Antragsteller: Professor Dr. Christian Blodau, until 8/2016 (†)