Articles | Volume 10, issue 7
Biogeosciences, 10, 4751–4765, 2013

Special issue: Ecosystems in transition: interactions and feedbacks with...

Biogeosciences, 10, 4751–4765, 2013

Research article 15 Jul 2013

Research article | 15 Jul 2013

Dynamics, chemical properties and bioavailability of DOC in an early successional catchment

U. Risse-Buhl1, F. Hagedorn2, A. Dümig3, M. O. Gessner7,6,5,4, W. Schaaf8, S. Nii-Annang8, L. Gerull1, and M. Mutz1 U. Risse-Buhl et al.
  • 1Department of Freshwater Conservation, Brandenburg University of Technology Cottbus, Seestraße 45, 15526 Bad Saarow, Germany
  • 2Department of Soil Sciences, Swiss Federal Institute of Forest, Snow and Landscape Research, Züricherstrasse 111, 8903 Birmensdorf, Switzerland
  • 3Lehrstuhl für Bodenkunde, Department für Ökologie und Ökosystemmanagement, Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt, Technische Universität München, 85350 Freising-Weihenstephan, Germany
  • 4Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Alte Fischerhütte 2, 16775 Stechlin, Germany
  • 5Department of Ecology, Berlin Institute of Technology (TU Berlin), Ernst-Reuter-Platz 1, 10587 Berlin, Germany
  • 6Department of Aquatic Ecology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland
  • 7Institute of Integrative Biology (IBZ), ETH Zurich, 8092 Zurich, Switzerland
  • 8Department of Soil Protection and Recultivation, Brandenburg University of Technology Cottbus, Konrad-Wachsmann-Allee 6, 03046 Cottbus, Germany

Abstract. 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, source, 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, stream water, subsurface water in an alluvial fan, and pond water all had high DOC concentrations (averages: 6.0–11.6 mg DOC L–1), despite small carbon stocks in both vegetation and soil of the catchment. Solid-state CPMAS 13C NMR of DOC in upwelling ground water revealed a higher proportion of aromatic compounds (32%) and a lower proportion of carbohydrates (33%) than in pond water (18% and 45%, respectively). The average 14C age of DOC in upwelling ground water was 2600 to 2900 yr, while organic matter of the Quaternary substrate of the catchment had a 14C age of 3000 to 16 000 yr. Both the 14C age data and 13C NMR spectra suggest that DOC partly derived from organic matter of the Quaternary substrate (about 40 to 90% of the C in the DOC), indicating that both recent and old C of the DOC can support microbial activity during early ecosystem succession. However, in a 70 day incubation experiment, only about 11% of the total DOC was found to be bioavailable. This proportion was irrespective of the water type. Origin of the microbial communities within the catchment (enriched from soil, stream sediment or pond water) also had only a marginal effect on overall DOC utilization.

Final-revised paper