International workshop on

  
Koli (c) Metla/Erkki Oksanen

Development of Models and Forest Soil Surveys for Monitoring of Soil Carbon

April 5-8, 2006 at Koli, Finland
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Modelling soil carbon sequestration of forest soils for different nitrogen fertilization and deposition levels

Annemieke Gärdenäs1 & Henrik Eckersten2

1 Dep. of Soil Sciences, SLU, Uppsala, Sweden, Annemieke.Gardenas@mv.slu.se,
2 Dep. of Crop Production Ecology, SLU, Uppsala, Sweden, Henrik.Eckersten@vpe.slu.se.

The long-term effects of N fertilization and N deposition on the carbon and nitrogen balances of forest stands in Sweden were studied (Gärdenäs et al. 2003; Gärdenäs & Eckersten 2006). Fluxes of carbon and nitrogen were dynamically coupled with the SOILN model (Eckersten et al. 1998) and calculated as a function of water and heat fluxes, which in their turn were simulated with the CoupModel (Jansson & Karlberg, 2001). Three main forested vegetation zones in Sweden (pine in northern and central Sweden, and spruce in southern Sweden) were represented with their own climate, soil type, stem production and N deposition level. The simulations were done for a whole forest rotation period (75-100 years). The tested N deposition levels were 50 %, 100 % and 150 % of the level in 1996 for each region. A single N fertilization dose was set to 150 kg/ha. The maximum total fertilization for each region followed the fertilization recommendations by the National Board of Forestry Sweden with 0, 300 and 600 kg N per ha and rotation period for southern, central and northern Sweden, respectively.

The uptake of organic N by the plant (presumably by symbiosis with mycorrhiza) was shown to be essential to simulate biomass production and plant N content of the same magnitude as that found in the literature. We found that soil C sequestration increased most with N deposition level in central Sweden. Increasing deposition level enhanced plant growth and N demand to such a degree that uptake of organic N was also stimulated. The uptake of organic N caused less soil respiration than uptake of mineral N and had a positive feedback on C sequestration (see also Aber et al. 1998; Beier et al., 2001). The effect of N fertilization on soil C sequestration depended on the N deposition level. We conclude that C sequestration is, in a complex way, sensitive to N addition rate, plant growth and climatic conditions. These relationships need to be considered in assessments of climate and management (change) impacts on soil C sequestration.

  • Aber, J. McDowell, W., Nadelhoffer, K., Magill, A., Berntson, G., Kamakea, M., McNulty, S., Currie, W., Rustad, L. Fernandez, I. 1998. Nitrogen saturation in temperate forest ecosystems. Hypotheses revisited. BioScience 48: 921-934.
  • Beier, C., Eckersten, H., Gundersen, P., 2001. Nitrogen cycling in a Norway spruce plantation in Denmark - A SOILN model application including organic N uptake. The ScientificWorld v. 1 (no.S2) p. 394-406
  • Eckersten, H., Jansson, P-E., & Johnsson, H. 1998. SOILN model, user´s manual. Version 9.2. Swed. Univ. Agric. Sci., Dep. Soil Sci., Communications 98:6, 113 pp.
  • Gärdenäs, A, Eckersten, H. & Lillemägi, M. 2003. Modeling long-term effects of N fertilization and N deposition on the N balance of forest stands in Sweden. 30 pp. Emergo 2003:3
  • Gärdenäs, A. & Eckersten, H. 2006. 100 Years of nitrogen leaching under various levels of N fertilization and N deposition from forest stands in Sweden – a modeling study. (in prep.)
  • Jansson, P-E. & Karlberg, L. 2001. COUP model - Coupled heat and mass transfer model for soil-plant-atmosphere system. Dept. of Civil and Environmental Engineering, Royal Institute of Technology.
 
   Päivitetty:   02.03.2006 / EKel Metla : Events   Palaute Metlan etusivulle
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