Abstract

The DyDOC model was used to simulate the soil carbon cycle of a deciduous forest at the Oak Ridge Reservation (Tennessee, USA). The model application relied on extensive data from the Enriched Background Isotope Study (EBIS), which exploited a short-term local atmospheric enrichment of radiocarbon to establish a large-scale manipulation experiment with different inputs of 14Cfromboth above-ground and below-ground litter. The model was first fitted to hydrological data, then observed pools and fluxes of carbon and 14C data were used to fit parameters describing metabolic transformations of soil organic matter (SOM) components and the transport and sorption of dissolved organic matter (DOM). This produced a detailed quantitative description of soil C cycling in the three horizons (O, A, B) of the soil profile. According to the parameterised model, SOM turnover within the thin O-horizon rapidly produces DOM (46 gC m-2 a-1), which is predominantly hydrophobic. This DOM is nearly all adsorbed in the A- and B-horizons, and while most is mineralised relatively quickly, 11 gC m-2 a-1 undergoes a ‘‘maturing’’ reaction, producing mineral-associated stable SOM pools with mean residence times of 100–200 years. Only a small flux (*1 gC m-2 a-1) of hydrophilic DOM leaves the B-horizon. The SOM not associated with mineral matter is assumed to be derived fromroot litter, and turns over quite quickly (mean residence time 20–30 years). AlthoughDyDOCwas successfully fitted to C pools, annual fluxes and 14C data, it accounted less well for short-term variations in DOC concentrations

Keywords

14C; Carbon Cycling; Dissolved organic carbon; Dissolved organic matter; DyDOC model; Enriched Background Isotope Study; Litter manipulation; Soil

Published in

Biogeochemistry
2012, Volume: 108, number: 1-3, pages: 91-107

SLU Authors

• Fröberg, Mats

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences
Geosciences, Multidisciplinary


Publication identifier

DOI: https://doi.org/10.1007/s10533-011-9575-1

Permanent link to this page (URI)

https://res.slu.se/id/publ/37935