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| 2. |
- Akselsson, Cecilia, et al.
(författare)
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Scaling and Mapping Regional Calculations of Soil Chemical Weathering Rates in Sweden
- 2004
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Ingår i: Water, Air, & Soil Pollution: Focus. - 1573-2940. ; 4:2-3, s. 671-681
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Tidskriftsartikel (refereegranskat)abstract
- Weathering rates of base cations are crucial in critical load calculations and assessments of sustainable forestry. The weathering rate on a single site with detailed geological data can be modelled using the PROFILE model. For environmental assessments on a regional scale, the weathering rates for sites are scaled into regional maps. The step from sites to regional level requires focus on the spatial variation of weathering rates. In this paper, a method is presented by which weathering rates are calculated for 25589 Swedish sites with total elemental analysis for the soil. Based on a part of the results, a methodology for creating area covering maps by geostatistical analysis and kriging is described. A normative reconstruction model was used to transform total elemental analysis to mineralogy. Information from the Swedish Forest Inventory database and other databases were used to derive texture and other important information for the sites, e.g. climate, deposition and vegetation data. The calculated weathering rates show a regional pattern that indicates possibilities for interpolation of data in large parts of Sweden. Geostatistical analysis of an area in southern Sweden shows different properties for different base cations. Kriging was performed for potassium to demonstrate the method. It was concluded that different base cations and different regions have to be analysed separately, in order to optimise the kriging method.
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| 3. |
- Akselsson, Cecilia, et al.
(författare)
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The influence of N load and harvest intensity on the risk of P limitation in Swedish forest soils
- 2008
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 1879-1026 .- 0048-9697. ; 404, s. 284-289
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) is often considered to be the major factor limiting tree growth in northern forest ecosystems. An increased N availability, however, increases the demand for other nutrients such as base cations and phosphorous (P) which in turn may change which nutrient is the limiting factor. If P or base cations become limiting, N will start to leach which means a risk of increased eutrophication of surface waters. As many studies focus on base cations, this study instead aims at estimating P budgets on a regional scale for different harvesting scenarios relevant for Swedish conditions. P budget calculations were carried out for 14,550 coniferous sites from the Swedish National Forest Inventory, as weathering+deposition–harvesting–leaching. Three scenarios with different harvest intensities were used: 1) no harvesting, 2) stem harvesting and 3) wholetree harvesting. The input data were derived from measurements and model results. The P budget estimates indicate that harvesting, especially whole-tree harvesting, result in net losses of P in large parts of Sweden. The highest losses were found in southern Sweden due to high growth rate in this area. In the whole-tree harvesting scenario the losses exceeded 1 kg ha−1 y−1 on many sites. N budget calculations on the same sites indicate that N generally accumulates in the whole country and especially in the southern parts. Consequently, the N and P budget calculations indicate that the forests in southern Sweden are in a transition phase from N-to P-limitation to growth. This transition will proceed as long as the accumulation of N continues. These results are important in a sustainable forestry context, as a basis for assessing the risk of future N leaching, and in designing recommendations for abatement strategies of N deposition and for application of wood ash recycling and N fertilization.
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| 5. |
- Alveteg, Mattias, et al.
(författare)
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Developing a kinetic alternative in modeling soil aluminium.
- 1995
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Ingår i: Water, Air and Soil Pollution. - 1573-2932. ; 79:1-4, s. 377-389
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Tidskriftsartikel (refereegranskat)abstract
- Soil chemistry models often use gibbsite solubility and similar equilibrium models to predict Al concentrations in soil solution. A kinetic alternative was developed with the goal of finding universal rate constants instead of the site- and depth-specific solubility constants usually associated with the equilibrium approach. The behavior of the two approaches was studied within the framework of the steady-state soil chemistry model PROFILE using data from Solling, Germany and Gårdsjön, Sweden, two sites with different mineralogy and land use history. The kinetic alternative uses a mass balance to predict Al concentrations. The sources of Al in soil water are deposition, weathering and mineralization. The sinks are leaching and the formation of an aluminosilicate precursor. The precursor slowly transforms into an ordinary clay mineral. Both formation and transformation of the precursor are treated as irreversible processes. The kinetic model introduces a new relationship between pH and Al and produces a systematic pattern of different apparent gibbsite equilibrium constants at different depths. Results show that the kinetic model systematically underestimates Al concentration in the upper horizons, which indicates that there may be additional sources of Al in the upper horizons not accounted for in the model. Predicted values of pH and Al concentrations are comparable with field observations.
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| 6. |
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| 7. |
- Alveteg, Mattias
(författare)
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Dynamics of forest soil chemistry
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Acidification caused by emissions of Nitrogen and Sulphur and associated adverse effects on forest ecosystems has been an issue on the political agenda for decades. Temporal aspects of soil acidification and/or recovery can be investigated using the soil chemistry model SAFE, a dynamic version of the steady-state model PROFILE used in critical loads assessment on the national level, e.g. for Sweden. In this thesis, possibilities to replace the use of apparent gibbsite solubility coefficients with a more mechanistic Al submodel are investigated and a reconstruction model, MAKEDEP, is presented which makes hindcasts and forecasts of atmospheric deposition and nutrient uptake and cycling. A regional application of SAFE/MAKEDEP based on 622 sites in Switzerland is also presented. It is concluded that the quantitative information on pools and fluxes of Al in forest ecosystems is very limited and that there currently exists no mechanistic alternative in modelling soil solution Al. MAKEDEP is a valuable and operational tool for deriving input to dynamic soil chemistry models such as SMART, MAGIC and SAFE. For multi-layer models, e.g. the SAFE model, including nutrient cycling in MAKEDEP is shown to be important. The strength of the regional assessment strategy presented in this thesis lies in its transparency and modularity. All submodules, including models, transfer functions, assumptions in the data acquisition strategy, etc., can be checked and replaced individually. As the presented assessment strategy is based on knowledge and data from a wide range of scientists and fields it is of vital importance that the research community challenge the assumptions made. The many measurable intermediate results produced by the included models will hopefully encourage scientists to challenge the models through additional measurements at the calculation sites. It is concluded that current reduction plans are not sufficient for all forest ecosystems in Switzerland to recover from acidification. Accordning to model projections, nearly 40 % of the sites will have a base cation to Al ratio below one by year 2050.
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| 9. |
- Alveteg, Mattias, et al.
(författare)
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Egen formulering, plagiat eller kopia. Hur höjer vi ribban för vad studenten anser vara fusk?
- 2004
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Ingår i: Andra Pedagogiska Inspirationskonferensen. ; , s. 43-45
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Konferensbidrag (refereegranskat)abstract
- Fusk och plagiat är något av en ödesfråga för den högre utbildningen. Om studenter klarar sig igenom kurser på grund av fusk hotas allmänhetens och arbetsgivarnas förtroende för den högre utbildningen. Tyvärr råder det idag en avsevärd oenighet om var gränsen för fusk går. Vi anser det därför vara hög tid att vi som lärare tar vårt ansvar och diskuterar dessa frågor ingående samt ger tips till varandra om hur fusk kan undvikas och upptäckas.
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| 10. |
- Alveteg, Mattias, et al.
(författare)
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Evaluating simplifications used in regional applications of the SAFE and MAKEDEP models
- 1998
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Ingår i: Ecological Modelling. - 0304-3800. ; 107:2-3, s. 265-277
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Tidskriftsartikel (refereegranskat)abstract
- The importance of different additional simplifications used when moving from single site applications to regional applications of the SAFE and MAKEDEP models was studied. The SAFE model is a dynamic soil chemistry model, which apart from physical and chemical soil parameters also needs the historic evolution of atmospheric deposition and nutrient uptake to simulate the effects of acidic deposition on the chemical status of forest soils. The historic evolution of atmospheric deposition and nutrient uptake are reconstructed by the MAKEDEP model, using information on current deposition and nutrients status together with general deposition trends. Additional simplifica- tions are enforced by limitations in available regional data sets and the costs involved in completing regional data sets. The simplifications studied here are the same as those used in an actual regional application to Scania, southern Sweden: (1) Use of default values for certain soil parameters such as dissolved organic carbon (DOC) and soil bulk density; (2) Use of general depth trends to extrapolate soil parameters, such as mineralogy and surface area, measured for one soil layer to the other three soil layers considered in the SAFE model application; (3) Use of a simplified version of MAKEDEP, where some of the key feedbacks, such as the effects of a growing canopy on dry deposition rates have been removed in order to limit the input data needed to run the MAKEDEP model. The models where applied to two well documented sites, Solling, Germany and Rothamsted, UK. Model results using the above simplifications and subsets thereof were compared with soil chemistry measurements and model results based on previously published single-site applications for the two sites. The study shows that the trends and the present day values of pH and base cation concentration are reproduced fairly well even when all of the simplifications are used. In order to increase the reliability of the regional applications, however, the non-simplified version of MAKEDEP should be used rather than the simplified version. Regional data sets of standing biomass and nutrient contents are therefore needed.
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