TY - GEN A1 - Dümig, Alexander A1 - Veste, Maik A1 - Hagedorn, Frank A1 - Fischer, Thomas A1 - Lange, Philipp A1 - Spröte, Roland A1 - Kögel-Knabner, Ingrid T1 - Organic matter from biological soil crusts induces the initial formation of sandy temperate soils T2 - Catena N2 - Different development stages of algae-dominated and moss-dominated biological soil crusts (BSCs) were sampled on a natural sand dune (b17 years old) and on an experimental sand dune (b8 years old) along a catena, including gradients of vegetation cover, location on the slope, as well as composition and thickness of BSC organisms in northeastern Germany. The accumulation of BSC-derived organic carbon (OC)was determined for bulk materials and fractions less than 63 μm. The OC composition was characterized by solid-state 13C NMR spectroscopy and the carbohydrate-C signature. 14C contents were determined to assess the origin and dynamics of OC. From the radiocarbon contents, two OC pools were differentiated: recent BSC-derived and lignite-derived “old” OC. Downward movement of OC into the underlying substratewas found only undermoss-dominated BSCs at the old sand dune. BSC-derived OC was mainly composed of carbohydrate-C and, to a lesser extent, alkyl C and N-alkyl C, with considerably higher contributions of alkyl C in the young dune, indicating differences in the composition of extracellular polymeric substances produced by the BSCs with age. This is consistent with higher proportions of water-soluble OC of moss-dominated BSCs at the old dune, which is leached in the underlying substrate and initiates soil formation. Because of the channeling effect of mosses, OC depth translocation along with suspended colloidal substances contribute to OC accumulation in substrates. Y1 - 2014 U6 - https://doi.org/10.1016/j.catena.2014.06.011 VL - 122 SP - 196 EP - 208 ER - TY - GEN A1 - Hüttl, Reinhard F. A1 - Gerwin, Werner A1 - Kögel-Knabner, Ingrid A1 - Schulin, Rainer A1 - Hinz, Christoph A1 - Subke, Jens-Arne T1 - Ecosystems in transition: interactions and feedbacks with an amphasis on the initial development T2 - Biogeosciences N2 - In this Special Issue of Biogeosciences on “Ecosystems in transition: Interactions and feedbacks with an emphasis on the initial development”, we bring together research on ecosystems undergoing state transitions, including artificially created and naturally formed sites, most of them in an initial stage of development. State transitions of an ecosystem may occur either when a formerly stable system state is disturbed or when a developing system gradually achieves new functions during succession. This special issue presents a collection of observational and experimental studies that focus on processes occurring during state transitions in the development of ecosystems and provide insights into the feedback mechanisms controlling them. These state transitions are studied at multiple scales, ranging from the pore scale to the catchment scale. The contributions collected in this issue can be divided into two main groups: (i) studies dealing with state transition occurring in initial ecosystems without active human interference, and (ii) studies dealing with active restoration of ecosystems after severe disturbances. Y1 - 2014 U6 - https://doi.org/doi:10.5194/bg-11-195-2014 VL - 11 SP - 195 EP - 200 ER -