title: Tracing the sources and spatial distribution of organic carbon in subsoils using a multi-biomarker approach.
abstract: Soil organic carbon (SOC) from aboveground and belowground sources has rarely been differentiated although it may drive SOC turnover and stabilization due to a presumed differing source dependent degradability. It is thus crucial to better identify the location of SOC from different sources for the parameterization of SOC models, especially in the less investigated subsoils. The aim of this study was to spatially assess contributions of organic carbon from aboveground and belowground parts of beech trees to subsoil organic carbon in a Dystric Cambisol. Different sources of SOC were distinguished by solvent-extractable and hydrolysable lipid biomarkers aided by (14)C analyses of soil compartments <63 μm. We found no effect of the distance to the trees on the investigated parameters. Instead, a vertical zonation of the subsoil was detected. A high contribution of fresh leaf- and root-derived organic carbon to the upper subsoil (leaf- and root-affected zone) indicate that supposedly fast-cycling, leaf-derived SOC may still be of considerable importance below the A-horizon. In the deeper subsoil (root-affected zone), roots were an important source of fresh SOC. Simultaneously, strongly increasing apparent (14)C ages (3860 yrs BP) indicate considerable contribution of SOC that may be inherited from the Pleistocene parent material.
authors.affiliation: Chair of Soil Science, Technical University of Munich, Emil-Ramann-Straße 2, D-85354 Freising, Germany.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Angst
authors.affiliation: Institute for Geology and Mineralogy, University of Cologne, Zülpicher Straße 49a, D-50674 Cologne, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: John
authors.affiliation: Chair of Soil Science, Technical University of Munich, Emil-Ramann-Straße 2, D-85354 Freising, Germany.
authors.forename: Carsten W
authors.initials: CW
authors.lastname: Mueller
authors.affiliation: Chair of Soil Science, Technical University of Munich, Emil-Ramann-Straße 2, D-85354 Freising, Germany.|Institute for Advanced Study, Technical University of Munich, Lichtenbergstraße 2a, D-85748 Garching, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Kögel-Knabner
authors.affiliation: Institute for Geology and Mineralogy, University of Cologne, Zülpicher Straße 49a, D-50674 Cologne, Germany.
authors.forename: Janet
authors.initials: J
authors.lastname: Rethemeyer