20.500.12556/DiRROS-23098 Explicit microrelief-controlled decoupling of initial aerobic decay and leaching (in hummocks) and anaerobic decay (in hollows) in surface layers of a Sphagnum-dominated peatland Understanding decay processes in peat deposits is fundamental for predicting their role as sources or sinks of atmospheric carbon in a changing environment. It is known that the distribution of microhabitats –hummock, lawn and hollow– within peatlands affects organic matter quality and degradation, but microtopography-dependent carbon dynamics are poorly understood on the molecular level. We studied early decomposition across microtopography levels through analyses of superficial moss cores from a Sphagnum-dominated ombrotrophic peatland in Central Germany, and a 400-day incubation experiment, using analytical pyrolysis. Interpretations were aided by analysis of living vegetation and a deep peat core as reference. Stable and labile pools of polysaccharides dominated the pyrolyzates and played a crucial role in decay dynamics. Two distinct degradation processes emerged: 1) anaerobic decay, characterized by loss of polysaccharides and selective preservation of lignin and aliphatic OM; and 2) leaching of labile phenolic compounds (including sphagnum acid) and free carbohydrates with concomitant initial aerobic degradation and selective preservation of structural polysaccharides. The relative importance of these initial decay processes is spatially dependent; anaerobic decay was detectable in only some of the more evolved hollow layers, while aerobic degradation and leaching dominated in hummocks. Sphagnum acid’s molecular markers appeared useful tracers of early decay as it probably has a leaching-sensitive component in hyaline cells (corroborated by SEM micrographs) that is lost rapidly from hummocks, but not from hollows. Hence, the occurrence of sphagnum acid in peat cores is influenced by microrelief position during peat accretion. This study highlights how microhabitat variations within peatlands influence decay mechanisms on the molecular level. Py-GC-MS THM-GC-MS peat organic matter polysaccharides Sphagnum acid true false true Elsevier Angleški jezik Ni določen Neznano 2025-07-25 03:38:25 2025-07-25 11:19:11 2025-10-24 03:53:09 0000-00-00 00:00:00 2025 0 0 14 str. vol. 192, [article no.] 107295 November 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2025-07-18 547 0165-2370 10.1016/j.jaap.2025.107295 243659523 1-s2.0-S0165237025003481-main.pdf 1-s2.0-S0165237025003481-main.pdf 1 5509092EA45C0A27D954186C1B8D31E6 688a72e90a4a99e9d135d050ca94b7ff41d7996a3e3b8109c2c03354ee1070b5 9005cf01-6943-11f0-9bb7-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=33859 Geološki zavod Slovenije 0 0 0