Abstract

Dissolved organic carbon (DOC) is a significant constituent in aquatic ecosystems with concentrations in streams influenced by both temperature and water flow pathway dynamics associated with changes in discharge (streamflow). We investigated the sensitivity of DOC concentrations in 12 high-latitude headwater streams to changes in temperature and discharge using a mathematical model. The implications of differences in sensitivities were explored by using downscaled projections of air temperature and discharge to simulate possible trajectories of DOC concentrations in a changing climate. We found two distinct responses: (i) catchments where stream DOC sensitivity was high to temperature but low to discharge and (ii) catchments where stream DOC sensitivity was low to temperature but high to discharge. Streams with strong seasonal DOC dynamics were more sensitive to temperature changes than nonseasonal systems. In addition, stream DOC sensitivity to discharge was strongly correlated with vertical soil water DOC differences in the near-stream zone. Simulations of possible future changes in DOC concentrations indicated median increases of about 4-24% compared to current levels when using projections of air temperature and discharge but even larger increases were observed for base flow concentrations (13-42%). Streams with high-temperature sensitivity showed the largest increases in DOC concentrations. Our results suggest that future climatic changes could bring significant increases in surface water DOC concentrations in boreal and hemiboreal areas but that the response ultimately is dependent on vertical soil solution DOC differences and soil organic carbon distribution.

Keywords

DOC; modeling; boreal; hemiboreal; uncertainty analysis; RIM

Published in

Journal of Geophysical Research: Biogeosciences
2016, Volume: 121, number: 1, pages: 126-144
Publisher: AMER GEOPHYSICAL UNION

SLU Authors

• Winterdahl, Mattias

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • Stockholm University
  • Uppsala University

• Laudon, Hjalmar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Bishop, Kevin

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • Uppsala University

Associated SLU-program

SLU Future Forests


UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1002/2015JG002922

Permanent link to this page (URI)

https://res.slu.se/id/publ/73051