Articles | Volume 12, issue 9
Biogeosciences, 12, 2791–2808, 2015

Special issue: Interactions between climate change and the Cryosphere: SVALI,...

Biogeosciences, 12, 2791–2808, 2015

Research article 12 May 2015

Research article | 12 May 2015

Carbon budget estimation of a subarctic catchment using a dynamic ecosystem model at high spatial resolution

J. Tang1,2, P. A. Miller1, A. Persson1, D. Olefeldt3, P. Pilesjö1, M. Heliasz1, M. Jackowicz-Korczynski1, Z. Yang4, B. Smith1, T. V. Callaghan5,6,7, and T. R. Christensen1,8 J. Tang et al.
  • 1Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, 223 62 Lund, Sweden
  • 2Department of Resource and Environmental Science, Wuhan University, Road Luoyu 129, Wuhan, China
  • 3Department of Renewable Resources, University of Alberta, Edmonton AB T6G 2H1, Canada
  • 4Department of Forest Ecosystems and Society, Oregon State University, Corvallis 973 31, Oregon, USA
  • 5Royal Swedish Academy of Sciences, Lilla Frescativägen 4A, 114 18 Stockholm, Sweden
  • 6Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
  • 7Department of Botany, National Research Tomsk State University, 36, Lenin Ave., Tomsk 634050, Russia
  • 8Arctic Research Centre, Aarhus University, C.F. Møllers Allé 8, 8000 Aarhus C, Denmark

Abstract. A large amount of organic carbon is stored in high-latitude soils. A substantial proportion of this carbon stock is vulnerable and may decompose rapidly due to temperature increases that are already greater than the global average. It is therefore crucial to quantify and understand carbon exchange between the atmosphere and subarctic/arctic ecosystems. In this paper, we combine an Arctic-enabled version of the process-based dynamic ecosystem model, LPJ-GUESS (version LPJG-WHyMe-TFM) with comprehensive observations of terrestrial and aquatic carbon fluxes to simulate long-term carbon exchange in a subarctic catchment at 50 m resolution. Integrating the observed carbon fluxes from aquatic systems with the modeled terrestrial carbon fluxes across the whole catchment, we estimate that the area is a carbon sink at present and will become an even stronger carbon sink by 2080, which is mainly a result of a projected densification of birch forest and its encroachment into tundra heath. However, the magnitudes of the modeled sinks are very dependent on future atmospheric CO2 concentrations. Furthermore, comparisons of global warming potentials between two simulations with and without CO2 increase since 1960 reveal that the increased methane emission from the peatland could double the warming effects of the whole catchment by 2080 in the absence of CO2 fertilization of the vegetation. This is the first process-based model study of the temporal evolution of a catchment-level carbon budget at high spatial resolution, including both terrestrial and aquatic carbon. Though this study also highlights some limitations in modeling subarctic ecosystem responses to climate change, such as aquatic system flux dynamics, nutrient limitation, herbivory and other disturbances, and peatland expansion, our study provides one process-based approach to resolve the complexity of carbon cycling in subarctic ecosystems while simultaneously pointing out the key model developments for capturing complex subarctic processes.

Final-revised paper