CH4and CO2production below two contrasting peatland micro-relief forms: An inhibitor and δ13C study.
Two peatland micro-relief forms (microforms) - hummocks and hollows - differ by their hydrological characteristics (water table level, i.e. oxic-anoxic conditions) and vegetation communities. We studied the CH4and CO2production potential and the localization of methanogenic pathways in both hummocks and hollows at depths of 15, 50, 100, 150 and 200cm in a laboratory incubation experiment. For this purpose, we measured CH4and CO2production rates, peat elemental composition, as well as δ13C values of gases and solids; the specific inhibitor of methanogenesis BES (2-bromo-ethane sulfonate, 1mM) was aimed to preferentially block the acetoclastic pathway. The cumulative CH4production of all depths was almost one fold higher in hollows than in hummocks, with no differences in CO2. With depth, CO2and CH4production decreased, and the relative contribution of the hydrogenotrophic pathway of methanogenesis increased. The highest methanogenic activity among all depths and both microforms was measured at 15cm of hollows (91%) at which the highest relative contribution of acetoclastic vs. hydrogenotrophic pathway (92 and 8%, respectively) was detected. For hummocks, the CH4production was the highest at 50cm (82%), where relative contribution of acetoclastic methanogenesis comprised 89%. The addition of 1mM BES was not selective and inhibited both methanogenic pathways in the soil. Thus, BES was less efficient in partitioning the pathways compared with the δ13C signature. We conclude that the peat microforms - dry hummocks and wet hollows - play an important role for CH4but not for CO2production when the effects of living vegetation are excluded.
Department of Soil Science of Temperate Ecosystems, Faculty of Forest Sciences and Forest Ecology, Georg-August University Göttingen, Büsgenweg 2, 37077 Göttingen, Germany.
Johannes
J
Krohn
Department of Soil Science of Temperate Ecosystems, Faculty of Forest Sciences and Forest Ecology, Georg-August University Göttingen, Büsgenweg 2, 37077 Göttingen, Germany.
Ivana
I
Lozanovska
Department of Soil Science of Temperate Ecosystems, Faculty of Forest Sciences and Forest Ecology, Georg-August University Göttingen, Büsgenweg 2, 37077 Göttingen, Germany; Department of Agricultural Soil Science, Georg-August University Göttingen, Büsgenweg 2, 37077 Göttingen, Germany.
Yakov
Y
Kuzyakov
Department of Soil Science of Temperate Ecosystems, Faculty of Forest Sciences and Forest Ecology, Georg-August University Göttingen, Büsgenweg 2, 37077 Göttingen, Germany.
Shahnaj
S
Parvin
Department of Soil Science of Temperate Ecosystems, Faculty of Forest Sciences and Forest Ecology, Georg-August University Göttingen, Büsgenweg 2, 37077 Göttingen, Germany. Electronic address: mdorodn@uni-goettingen.de.
Maxim
M
Dorodnikov
Boreal peatland; Greenhouse gases; Methanogenesis inhibitor; Methanogenic pathways; Micro-relief forms; Stable carbon isotope method