Artikkelit jotka sisältää sanan 'Carbon balance'
Models of 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
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Clymo,
School of Biological Sciences, Queen Mary and Westfield College, London El 4NS, UK
Sähköposti:
ei.tietoa@nn.oo
Mitä suoarkistot voivat meille tulevaisuudessa kertoa?
English title: What would be the significance of peat archives in the future?
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An attempt is made to predict the progress of mire palaeoecological research in the near future. The prognosis is made in the light of recent advances in the field. Examples of some multi-faceted topics are given. They include ancient climatic changes for understanding the present changes, the greenhouse-effect, problems and new innovations in dating, organic pollutants such as PAHs and DDT, heavy metals and related air pollutants, man-made radionuclides, initiation of peatlands, peat growth, and fire history.
Keywords: Carbon balance, dating, fire, DDT, global warming, heavy metals, PAHs
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Tolonen,
Department of Biology, University of Joensuu, P.O. Box 111, SF-80101 Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
Ojituksen ja lannoituksen vaikutus turpeen hiilen vapautumiseen ja ravinteiden mineralisoitumiseen.
English title: Effect of drainage and fertilization on carbon output and nutrient mineralization of peat.
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Carbon dioxide production increased to 2-3 fold from the peat of an oligotrophic sedge pine mire (VSR) after draining had lowered the water table to a depth c, 0.5 m. At two other sites, a mesotrophic sedge pine mire (RhSR) and a spruce swamp (MK), both the fall in the groundwater table and the increase in C02 production were smaller. At the VSR site, the fast-dissolving PK fertilizer and urea each caused a rapid increase while the slow-dissolving PK fertilizer a slow increase in soil respiration. The greatest, steady increase was achieved by treatment with wood ash. At RhSR and MK sites, the use of fertilizers generally led to a decline in soil respiration for 1-2 years, after which the initial level was normally regained. According to a simulation of the C02 production after drainage, the annual decomposition of peat was calculated to be c. 1 000 g (organic matter) m-2 in the VSR site. On the basis of this decomposition rate, the annual amount of nitrogen mineralizated was estimated to be c. 100 kg ha-1 and that of phosphorus c. 5 kg ha-1. Peat contains only a small amount of potassium, and the decomposition of old peat layers increases the amount of soluble potassium in peat very little.
Keywords: Carbon balance, drainage, fertilization, nutrient mineralization, peat decomposition
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Silvola,
Department of Biology, University of Joensuu, P.O. Box 111, SF-80101 Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
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