TY - CONF A1 - Risse-Buhl, Ute A1 - Hagedorn, Frank A1 - Dümig, Alexander A1 - Gessner, Mark O. A1 - Schaaf, Wolfgang A1 - Nii-Annang, Seth A1 - Gerull, Linda A1 - Mutz, Michael A2 - Jeltsch, Florian A2 - Joshi, Jasmin T1 - Dynamics, chemical properties and bioavailability of DOC in an early successional catchment T2 - GfÖ 43rd Annual Meeting, Building bridges in ecology, linking systems, scales and disciplines, September 9 to 13, 2013, Potsdam, Germany N2 - The dynamics of dissolved organic carbon (DOC) have been intensively studied in mature ecosystems, but little is known about DOC dynamics and the significance of DOC as a substrate for microbial activity in early-successional catchments. We determined the concentration, chemical composition, radiocarbon age, and bioavailability of DOC along the hydrological flow path from soil solution to a downstream pond in a recently constructed catchment (Chicken Creek Catchment, Germany). Soil solution, upwelling ground water, subsurface water in an alluvial fan, and pond water all had high DOC concentrations (averaged 6.0 – 11.6 mg DOC L‐1), despite small carbon stocks in either vegetation or soil of the catchment. The mean 14C age of DOC in upwelling ground water was 2600 to 2800 years. Solid-state CPMAS 13C NMR revealed a higher proportion of aromatic compounds (32%) and a lower proportion of carbohydrates (33%) in upwelling ground water compared to pond water (18% and 45%, respectively). 14C age and 13C NMR spectra suggest that DOC was partly mobilized from charred organic matter inherent in the Quaternary substrate. In a 70-days incubation experiment, 20% of the total DOC was found to be bioavailable, irrespective of the water type. Origin of the microbial communities within the catchment (enriched from soil, stream sediment or pond water) had only marginal effects on overall DOC utilization. Overall, our data suggest that both recent and old DOC support microbial activity during early ecosystem succession, although a large fraction of the DOC is recalcitrant and eventually exported from the catchment once it has been mobilized. Y1 - 2013 UR - https://opus4.kobv.de/opus4-UBICO/frontdoor/index/index/docId/9396 SP - S. 377 PB - Gesellschaft für Ökologie CY - Berlin ER -