Artikkelit jotka sisältää sanan 'modelling'

Michael Trepel, Torbjörn Davidsson, Sven-Erik Jørgensen. Quantitative simulation of biochemical processes in peatlands as a tool to define sustainable use.
Avainsanat: nitrogen; peatland; modelling; restoration; denitrification
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A natural property of mires is their ability to accumulate carbon and nutrients in the form of peat.Drainage and agricultural land use have changed the nutrient balance from accumulation to mobilisation.In this study, the effect of land use and hydrology on nitrogen dynamics is quantified using a GIS-based dynamic modelling approach.In the simulation, the nitrogen budget is controlled by drainage depth, land use type and fertilizer application.Denitrification is, next to harvest, the quantitatively most impor tant output pathway from peat soils with a predominant vertical water flow.Only for the wet Caricion elatae type was a net nitrogen accumulation simulated.The spatial visualisation of the nitrogen balance shows a high variability based on the heterogene ity of the peatland.Rewetting and extensivication can reduce the deficit in the nitrogen balance and lead to a slight increase of the accumulating area.These simulation results can be used in environmental planning to define a more sustainable land use in the future.
  • Trepel, Royal Danish School of Pharmacy, Section of Environmental Chemistry, Universitetsparken 2, DK-2100 Copenhagen, Denmark Sähköposti: ei.tietoa@nn.oo (sähköposti)
  • Davidsson, Sähköposti: ei.tietoa@nn.oo
  • Jørgensen, Sähköposti: ei.tietoa@nn.oo
R. S. Clymo. Models of peat growth.
Avainsanat: peatland; Carbon balance; modelling; peat growth
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Models reflect reality but also simplify it. The modeller must choose where the balance lies between simplicity plus understanding and complexity plus realism. (1) Two pictorial and descriptive models of the surface of a peat-forming bog are given, and a third shows why the true rate of peat accumulation must diminish over time. (2) A simple quantitative model of the surface layers is described and leads to the conclusion that the surface layer is in a steady state, fixing carbon, losing some by decay, and passing some on to the underlying peat proper. A similar model for the underlying peat shows that if decay is at a rate that is a constant proportion of what remains then there is an upper asymptotic limit to the depth of peat. But if the rate of decay decreases, because the remaining material is more refractory, then peat accumulation continues indefinitely though at an ever-decreasing rate. (3) A simulation model allowing greater realism but diminished understanding is outlined. (4) Models should be aids, not objects in their own right. Keywords: Carbon balance, modelling, peat growth, peatland
  • Clymo, School of Biological Sciences, Queen Mary and Westfield College, London El 4NS, UK Sähköposti: ei.tietoa@nn.oo (sähköposti)

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