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  • 1. Ben-Gal, A.
    et al.
    Karlberg, L.
    Jansson, Per-Erik.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Shani, U.
    Temporal robustness of linear relationships between production and transpiration2003In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 251, no 2, p. 211-218Article in journal (Refereed)
    Abstract [en]

    Seasonal dependence of biomass production on transpiration has been previously reported for a number of crops under salinity and drought. Linear yield (Y) to transpiration ( T) relationships have been utilized in plant-growth and water-uptake models to estimate yield based on predicted transpiration values. The relationship is often employed for time steps that are very small compared with the whole season measurements, even though no empirical validation exists for such application. This work tests the hypothesis that linear Y-T relationships are valid throughout the life span of crops under varied natural conditions and levels of environmental stress. Effects of salinity and water supply on growth, water use and yields of tomatoes ( Lycopersicon esculentum Mill.) were studied for two distinct conditions of potential transpiration. Linear relationships between relative Y and relative ET were found to be consistent throughout the life span of the crops for both growing seasons. Water-use efficiency increased together with plant growth as a result of changes in the plant's surface area to volume ratio. This empirical validation of linear Y-T relationships for short time periods is beneficial in confirming their usefulness in growth and water uptake models.

  • 2. Berggren Kleja, Dan
    et al.
    Svensson, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Majdi, Hooshang
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Langvall, Ola
    Bergkvist, Bo
    Johansson, Maj-Britt
    Weslien, Per
    Lindroth, Anders
    Pools and fluxes of carbon in three Norway spruce ecosystems along a climatic gradient in Sweden.2008In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 89, no 1, p. 7-25Article in journal (Refereed)
    Abstract [en]

    This paper presents an integrated analysis of organic carbon (C) pools in soils and vegetation, within-ecosystem fluxes and net ecosystem exchange (NEE) in three 40-year old Norway spruce stands along a north-south climatic gradient in Sweden, measured 2001-2004. A process-orientated ecosystem model (CoupModel), previously parameterised on a regional dataset, was used for the analysis. Pools of soil organic carbon (SOC) and tree growth rates were highest at the southernmost site (1.6 and 2.0-fold, respectively). Tree litter production (litterfall and root litter) was also highest in the south, with about half coming from fine roots (< 1 mm) at all sites. However, when the litter input from the forest floor vegetation was included, the difference in total litter input rate between the sites almost disappeared (190-233 g C m(-2) year(-1)). We propose that a higher N deposition and N availability in the south result in a slower turnover of soil organic matter than in the north. This effect seems to overshadow the effect of temperature. At the southern site, 19% of the total litter input to the O horizon was leached to the mineral soil as dissolved organic carbon, while at the two northern sites the corresponding figure was approx. 9%. The CoupModel accurately described general C cycling behaviour in these ecosystems, reproducing the differences between north and south. The simulated changes in SOC pools during the measurement period were small, ranging from -8 g C m(-2) year(-1) in the north to +9 g C m(-2) year(-1) in the south. In contrast, NEE and tree growth measurements at the northernmost site suggest that the soil lost about 90 g C m(-2) year(-1).

  • 3. Blomqvist, Göran
    et al.
    Riehm, Mats
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    ROAD SURFACE WETNESS AS AFFECTED BY EVAPORATION, SURFACE RUNOFF AND TRAFFIC SPLASHINGManuscript (preprint) (Other academic)
    Abstract [en]

    Road surface wetness governs the fate of pollutants on the road surface. The wetness is also important for estimating the risk of ice formation during winters. The road surface water is affected by evaporation, run-off and traffic induced splash and spray. Increased knowledge of how these processes govern the road surface water and how they could be modelled would help to improve the possibility to abate problems with raised levels of air pollutants, as well as traffic safety issues by facilitating optimization of the use of anti- and de-icing chemicals. The aim of this study was to use a modeling tool in order to differentiate between three processes governing the loss of wetness from the road surface within a cross section of a road during two different climatic scenes (winter and spring). Two new measurement techniques were used for detailed measurements of road surface wetness across a road to validate the model. It could be concluded that the changes in wetness on the road can be simulated from general simple weather and traffic information. Furthermore, the wetness across the road is very heterogeneous and can be described by a distribution of regulating parameter values. The presented model application has a potential for real time application on roads and within a region and also for predictions of future conditions by using weather forecast data.

  • 4. Christiansen, J. R.
    et al.
    Elberling, B.
    Jansson, Per-Erik.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Modelling water balance and nitrate leaching in temperate Norway spruce and beech forests located on the same soil type with the CoupModel2006In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 237, no 03-jan, p. 545-556Article in journal (Refereed)
    Abstract [en]

    Two contrasting forest ecosystems located in close proximity to each other were selected for evaluating the importance of tree species and afforestation in relation to the water balance and the quality of the water leaving the forest root zone. Measurements included soil water content and the collection of precipitation, canopy throughfall, stem flow and soil solution on a weekly basis during 15 months (1999-2000). Soil solutions were extracted using suction probes installed at all major horizons within the upper 120 cm of a Norway spruce (N. spruce) stand (Picea Abies [L.] Karst.) and a European beech stand (Fagus Sylvatica L.) located on the same soil type. Soil solutions were analyzed for the content of all major ions, including nitrate. A water balance model (CoupModel) was used to estimate percolation rates beneath the root zone. Percolation at the beech stand was 292 mm and only 41 rnm at the N. spruce stand mainly due to differences in the interception loss. The highest annual leaching of Mg, K, Na, Al, Cl, SO4-S was noted in the N. spruce stand while leaching of NO3-N was highest in the beech stand, corresponding to 39 kg ha(-1) year(-1). By contrast, the annual leaching of NO3-N in the N. spruce stand was only 0.5 kg ha(-1) year(-1). The larger amount of NO3-N was leaving the beech forest soil despite the fact that the N. spruce stand had the highest atmospheric N-deposition. Thus, differences in NO3-N leaching between the stands must be related to differences in uptake and accumulation of N in the vegetation and within the upper 120 cm of the soil. Differences in the water balance and NO3-N leaching between beech and N. spruce stands call for further attention to the selection of tree-species on a soil type basis when planning future afforestation projects, particularly when such projects aim to improve the quality of water infiltrating to the groundwater zone.

  • 5. Coucheney, E.
    et al.
    Eckersten, H.
    Hoffmann, H.
    Jansson, Per Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Gaiser, T.
    Ewert, F.
    Lewan, E.
    Key functional soil types explain data aggregation effects on simulated yield, soil carbon, drainage and nitrogen leaching at a regional scale2018In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 318, p. 167-181Article in journal (Refereed)
    Abstract [en]

    The effects of aggregating soil data (DAE) by areal majority of soil mapping units was explored for regional simulations with the soil-vegetation model CoupModel for a region in Germany (North Rhine-Westphalia). DAE were analysed for wheat yield, drainage, soil carbon mineralisation and nitrogen leaching below the root zone. DAE were higher for soil C mineralization and N leaching than for yield and drainage and were strongly related to the presence of specific soils within the study region. These soil types were associated to extreme simulated output variables compared to the mean variable in the region. The spatial aggregation of these key functional soils within sub-regions additionally influenced the DAE. A spatial analysis of their spatial pattern (i.e. their presence/absence, coverage and aggregation) can help in defining the appropriate grid resolution that would minimize the error caused by aggregating soil input data in regional simulations.

  • 6. Elberling, Bo
    et al.
    Søndergaard, Jens
    Jensen, Louise A.
    Schmidt, Lea B.
    Hansen, Birger U.
    Asmund, Gert
    Balic-Zunic, Tonci
    Hollesen, J. Orgen
    Hanson, Susanne
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Friborg, Thomas
    Arctic vegetation damage by winter-generated coal mining pollution released upon thawing2007In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 41, no 7, p. 2407-2413Article in journal (Refereed)
    Abstract [en]

    Acid mine drainage (known as AMD) is a well-known environmental problem resulting from the oxidation of sulfidic mine waste. In cold regions, AMD is often considered limited by low temperatures most of the year and observed environmental impact is related to pollution generated during the warm summer period. Here we show that heat generation within an oxidizing, sulfidic, coal-mining waste-rock pile in Svalbard (78 degrees N) is high enough to keep the pile warm (roughly 5 degrees C throughout the year) despite mean annual air temperatures below -5 degrees C. Consequently, weathering processes continue year-round within the waste-rock pile. During the winter, weathering products accumulate within the pile because of a frozen outer layer on the pile and are released as a flush within 2 weeks of soil thawing in the spring. Consequently, spring runoff water contains elevated concentrations of metals. Several of these metals are taken up and accumulated in plants where they reach phytotoxic levels, including aluminum and manganese. Laboratory experiments document that uptake of Al and Mn in native plant species is highly correlated with dissolved concentrations. Therefore, future remedial actions to control the adverse environmental impacts of cold region coal-mining need to pay more attention to winter processes including AMD generation and accumulation of weathering products.

  • 7.
    Gustafsson, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Gärdenäs, Annemieke
    Department of Soil and Environment, Swedish University of Agricultural Sciences.
    Eckersten, Henrik
    Department of Ecology and Crop Production, Swedish University of Agricultural Sciences.
    Simulated carbon and water processes of forest ecosystems in Forsmark and Oskarshamn during a 100-year period2006Report (Other academic)
  • 8.
    Gustafsson, David
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Jansson, Per-Erik
    Lewan, E
    Water and heat balance of the boreal landscape: comparison of forest and arable land.Manuscript (preprint) (Other academic)
  • 9.
    Gustafsson, David
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Lewan, E.
    Jansson, Per-Erik
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Modeling water and heat balance of the boreal landscape - comparison of forest and arable land in Scandinavia2004In: Journal of applied meteorology (1988), ISSN 0894-8763, E-ISSN 1520-0450, Vol. 43, no 11, p. 1750-1767Article in journal (Refereed)
    Abstract [en]

    The water and heat balances of an arable field and a forest in the boreal zone in Scandinavia were explored using 3 yr of observations and simulations with two different soil - vegetation - atmosphere transfer (SVAT) models over a 30-yr period. Results from a detailed mechanistic model [ coupled heat and mass transfer model ( COUP)] were compared with those obtained with a large-scale type of SVAT model used in the weather prediction model at the European Centre for Medium-Range Weather Forecasts [ECMWF tiled land surface scheme (TESSEL)]. The COUP model simulations agreed well with the observations from a seasonal perspective. The TESSEL model differed significantly from the measurements when standard operational parameter values were used. The introduction of a seasonal variation in leaf-area index values, tuned canopy resistance for forest, and a reduced roughness length over snow-covered open land reduced the discrepancies. Net radiation was 40% higher in the forest when compared with the arable land, based on 30-yr simulations with both models. Furthermore, the forest was a net source of sensible heat flux, whereas the arable land was a net sink. Because of different treatment of winter interception evaporation, forest latent heat flux based on the COUP model considerably exceeded that from the TESSEL model, and suggested that the total annual evaporation was higher from the forest than from arable land. The representation of interception evaporation in winter, as well as seasonal dynamics in vegetation properties are, thus, of considerable importance for adequate simulation of forest and arable land energy fluxes within the boreal zone.

  • 10.
    Gustafsson, David
    et al.
    KTH, Superseded Departments, Civil and Environmental Engineering.
    Stahli, M
    Jansson, Per-Erik
    KTH, Superseded Departments, Civil and Environmental Engineering.
    The surface energy balance of a snow cover: comparing measurements to two different simulation models2001In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 70, no 1-4, p. 81-96Article in journal (Refereed)
    Abstract [en]

    We compared two one-dimensional simulation models for heat and water fluxes in the soil-snow-atmosphere system with respect to their mathematical formulations of the surface heat exchange and the snow pack evolution. They were chosen as examples of a simple one-layer snow model and a more detailed multiple-layer snow model (SNTHERM). The snow models were combined with the same one-dimensional model for the heat and water balance of the underlying soil (CoupModel). Data from an arable field in central Sweden (Marsta), covering two years (1997-1999) of soil temperature, snow depth and eddy-correlation measurements were successfully compared with the models. Conditions with a snow pack deeper or shallower than 10cm and bare soil resulted in similar discrepancies. The simulated net radiation and sensible heat flux were in good agreement with that measured during snow-covered periods, except for situations with snowmelt when the downward sensible heat flux was overestimated by 10-20 WM-2. The results showed that the uncertainties in parameter values were more important than the model formulation and that both models were useful in evaluating the limitations and uncertainties of the measurements.

  • 11.
    Gärdenäs, Annemieke
    et al.
    Department of Soil and Environment, Swedish University of Agricultural Sciences.
    Eckersten, Henrik
    Department of Ecology and Crop Production, Swedish University of Agricultural Sciences.
    Reinlert, André
    Dept. of Physical Geography and Ecosystems Analysis, Lund University.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Ekström, Per-Anders
    Facilia AB.
    Avila, Rodolfo
    Facilia AB.
    Greger, Maria
    Dept. of Botany, Stockholm University.
    Tracey - a simulation model of trace element fluxes in soil-plant system for long-term assessment of a radioactive groundwater contamination2009Report (Other academic)
  • 12.
    Gärdenäs, Annemieki
    et al.
    Department of Soil and Environment, Swedish University of Agricultural Sciences.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Physics.
    Karltun, Erik
    Department of Soil and Environment, Swedish University of Agricultural Sciences.
    Klemendtsson, Leif
    Department of Plant and Environmental Sciences, Gothenburg University.
    Lehtonen, Aleksi
    Finnish Forest Research Institute, Vantaa, Finland.
    Ortiz, Carina
    Department of Soil and Environment, Swedish University of Agricultural Sciences.
    Palosuo, Taru
    MTT Agrifood Research, Helsinki, Finland.
    Svensson, Magnus
    Department of Soil and Environment, Swedish University of Agricultural Sciences.
    Estimating soil carbon stock changes by process-based models and soil inventories: uncertainties and complementarities2011In: Soil Carbon in Sensitive European Ecosystems: From Science to Land Management / [ed] Robert Jandl, Mirco Rodehiero and Mats Olsson, Oxford: Wiley-Blackwell, 2011Chapter in book (Refereed)
    Abstract [en]

    In this chapter, four examples of scientific questions and challenges in which process-oriented modelling could provide a useful contribution for accounting soil organic carbon (SOC) stocks and changes are presented. These challenges include cases i) when measurements are either time-consuming and/or expensive or there are methodological limitations; ii) an attempt to verify the national soil inventory estimates through comparison with process-based model estimates; iii) prediction of the potential impact on SOC changes due to land-use change; and iv) a comparison of different scenarios for mitigating GHG-emissions. We found that the use of process-based models offers a complementary way to account SOC change and provides an option for assessing the potential impact of climate and land-use change on SOC stocks. However, uncertainty in model estimates is inherent and needs to be communicated. Progress has been made in the assessment of uncertainty and there is growing awareness of how this uncertainty can be communicated. Suggestions for collaborative approaches are presented in order to reduce the uncertainties.

  • 13.
    Hamisi, Rajabu
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Balfors, Berit
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Thunvik, Roger
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Hamerlynck, O
    Duvail, S
    Applications of Process Base Models for Sustainable Water Utilizations in a Competing Demands and Climate Variability: A Case of the Lower Rufiji, Tanzania2013Conference paper (Refereed)
  • 14. He, H.
    et al.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Svensson, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Meyer, A.
    Klemedtsson, L.
    Kasimir, Å.
    Factors controlling Nitrous Oxide emission from a spruce forest ecosystem on drained organic soil, derived using the CoupModel2016In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 321, p. 46-63Article in journal (Refereed)
    Abstract [en]

    High Nitrous Oxide (N2O) emissions have been identified in hemiboreal forests in association with draining organic soils. However, the specific controlling factors that regulate the emissions remain unclear. To examine the importance of different factors affecting N2O emissions in a spruce forest on drained organic soil, a process-based model, CoupModel, was calibrated using the generalized likelihood uncertainty estimation (GLUE) method. The calibration also aims to estimate parameter density distributions, the covariance matrix of estimated parameters and the correlation between parameters and variables information, useful when applying the model on other peat soil sites and for further model improvements. The calibrated model reproduced most of the high resolution data (total net radiation, soil temperature, groundwater level, net ecosystem exchange, etc.) very well, as well as cumulative measured N2O emissions (simulated 8.7±1.1kgN2Oha-1year-1 (n=97); measured 8.7±2.7kgN2Oha-1year-1 (n=6)), but did not capture every measured peak. Parameter uncertainties were reduced after calibration, in which 16 out of 20 parameters changed from uniform distributions into normal distributions or log normal distributions. Four parameters describing bypass water flow, oxygen diffusion and soil freezing changed significantly after calibration. Inter-connections and correlations between many calibrated parameters and variables reflect the complex and interrelated nature of pedosphere, biosphere and atmosphere interactions. This also highlights the need to calibrate a number of parameters simultaneously. Model sensitivity analysis indicated that N2O emissions during growing seasons are controlled by competition between plants and microbes for nitrogen, while during the winter season snow melt periods are important. Our results also indicate that N2O is mainly produced in the capillary fringe close to the groundwater table by denitrification in the anaerobic zone. We conclude that, in afforested drained peatlands, the plants and groundwater level have important influences on soil N availability, ultimately controlling N2O emissions.

  • 15. He, Hongxing
    et al.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Svensson, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Bjorklund, Jesper
    Tarvainen, Lasse
    Klemedtsson, Leif
    Kasimir, Asa
    Forests on drained agricultural peatland are potentially large sources of greenhouse gases - insights from a full rotation period simulation2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 8, p. 2305-2318Article in journal (Refereed)
    Abstract [en]

    The CoupModel was used to simulate a Norway spruce forest on fertile drained peat over 60 years, from planting in 1951 until 2011, describing abiotic, biotic and greenhouse gas (GHG) emissions (CO2 and N2O). By calibrating the model against tree ring data a "vegetation fitted" model was obtained by which we were able to describe the fluxes and controlling factors over the 60 years. We discuss some conceptual issues relevant to improving the model in order to better understand peat soil simulations. However, the present model was able to describe the most important ecosystem dynamics such as the plant biomass development and GHG emissions. The GHG fluxes are composed of two important quantities, the spruce forest carbon (C) uptake, 413 g C m(-2) yr(-1) and the decomposition of peat soil, 399 g C m(-2) yr(-1) . N2O emissions contribute to the GHG emissions by up to 0.7 g N m(-2) yr(-1), corresponding to 76 g C m(-2) yr(-1) . The 60-year old spruce forest has an accumulated biomass of 16.0 kg C m(-2) (corresponding to 60 kg CO2 m(-2)). However, over this period, 26.4 kg C m(-2) (97 kg CO2 eq m(-2)) has been added to the atmosphere, as both CO2 and N2O originating from the peat soil and, indirectly, from forest thinning products, which we assume have a short lifetime. We conclude that after harvest at an age of 80 years, most of the stored biomass carbon is liable to be released, the system having captured C only temporarily and with a cost of disappeared peat, adding CO2 to the atmosphere.

  • 16. He, Hongxing
    et al.
    Meyer, Astrid
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Svensson, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Rutting, Tobias
    Klemedtsson, Leif
    Simulating ectomycorrhiza in boreal forests: implementing ectomycorrhizal fungi model MYCOFON in CoupModel (v5)2018In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 11, no 2, p. 725-751Article in journal (Refereed)
    Abstract [en]

    The symbiosis between plants and Ectomycorrhizal fungi (ECM) is shown to considerably influence the carbon (C) and nitrogen (N) fluxes between the soil, rhizosphere, and plants in boreal forest ecosystems. However, ECM are either neglected or presented as an implicit, undynamic term in most ecosystem models, which can potentially reduce the predictive power of models. In order to investigate the necessity of an explicit consideration of ECM in ecosystem models, we implement the previously developed MYCOFON model into a detailed process-based, soil-plant-atmosphere model, Coup-MYCOFON, which explicitly describes the C and N fluxes between ECM and roots. This new Coup-MYCOFON model approach (ECM explicit) is compared with two simpler model approaches: one containing ECM implicitly as a dynamic uptake of organic N considering the plant roots to represent the ECM (ECM implicit), and the other a static N approach in which plant growth is limited to a fixed N level (nonlim). Parameter uncertainties are quantified using Bayesian calibration in which the model outputs are constrained to current forest growth and soil C / N ratio for four forest sites along a climate and N deposition gradient in Sweden and simulated over a 100-year period. The "nonlim" approach could not describe the soil C / N ratio due to large overestimation of soil N sequestration but simulate the forest growth reasonably well. The ECM "implicit" and "explicit" approaches both describe the soil C / N ratio well but slightly underestimate the forest growth. The implicit approach simulated lower litter production and soil respiration than the explicit approach. The ECM explicit Coup-MYCOFON model provides a more detailed description of internal ecosystem fluxes and feedbacks of C and N between plants, soil, and ECM. Our modeling highlights the need to incorporate ECM and organic N uptake into ecosystem models, and the nonlim approach is not recommended for future long-term soil C and N predictions. We also provide a key set of posterior fungal parameters that can be further investigated and evaluated in future ECM studies.

  • 17. Hollesen, J.
    et al.
    Elberling, B.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Future active layer dynamics and carbon dioxide production from thawing permafrost layers in Northeast Greenland2011In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 17, no 2, p. 911-926Article in journal (Refereed)
    Abstract [en]

    Thawing permafrost and the resulting mineralization of previously frozen organic carbon (C) is considered an important future feedback from terrestrial ecosystems to the atmosphere. Here, we use a dynamic process oriented permafrost model, the CoupModel, to link surface and subsurface temperatures from a moist permafrost soil in High-Arctic Greenland with observed heat production and carbon dioxide (CO2) release rates from decomposition of previously frozen organic matter. Observations show that the maximum thickness of the active layer at the end of the summer has increased 1 cm yr-1 since 1996. The model is successfully adjusted and applied for the study area and shown to be able to simulate active layer dynamics. Subsequently, the model is used to predict the active layer thickness under future warming scenarios. The model predicts an increase of maximum active layer thickness from today 70 to 80-105 cm as a result of a 2-6 degrees C warming. An additional increase in the maximum active layer thickness of a few centimetres may be expected due to heat production from decomposition of organic matter. Simulated future soil temperatures and water contents are subsequently used with measured basal soil respiration rates in a respiration model to predict the corresponding depth-integrated CO2 production from permafrost layers between 0.7 and 2 m below the surface. Results show an increase from present values of < 40 g C m-2 yr-1 to between 120 and 213 g C m-2 yr-1 depending on the magnitude of predicted warming. These rates are more than 50% of the present soil CO2 efflux measured at the soil surface. Future modelling accounting for snow, vegetation and internal biological heat feedbacks are of interest in order to test the robustness of the above predictions and to describe the entire ecosystem response.

  • 18. Hollesen, J.
    et al.
    Elberling, B.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Modelling temperature-dependent heat production over decades in High Arctic coal waste rock piles2011In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 65, no 2, p. 258-268Article in journal (Refereed)
    Abstract [en]

    Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures as the release of AMD normally is limited by permafrost. Here we show that temperatures within a 20 year old heat-producing waste rock pile in Svalbard (78 degrees N) can be modelled by the one-dimensional heat and water flow model (CoupModel) with a new temperature-dependent heat-production module that includes both biological and chemical oxidation processes and heat source depletion over time. Inputs to the model are meteorological measurements, physical properties of the waste rock material and measured subsurface heat-production rates. Measured mean annual subsurface temperatures within the waste rock pile are up to 10 C higher than the mean annual air temperature of -5.8 degrees C. Subsurface temperatures are currently decreasing with 0.5 degrees C per year due to decreasing heat production, which can be modelled using an exponential decay function corresponding to a half-life period of pyrite oxidation of 7 years. Simulations further suggest that subsurface temperatures two years after construction of the pile may have been up to 34.0 degrees C higher than in 2009 and that the release of AMD may have been more than 20 times higher. Sensitivity simulations show that maximum temperatures in the pile would have been up to 30.5-32.5 degrees C lower and that the pile would have been frozen 12-27 years earlier if the pile had been initially saturated with water, constructed with a thickness half of the original or a combination of both. Simulation show that the pile thickness and waste rock pyrite content are important factors controlling the internal build up of heat leading to potential self-incineration. However, site specific measurements of temperature-dependent heat production as well as simulation results show that the heat produced from pyrite oxidation alone cannot cause such a temperature increase and that processes such as heat production from coal oxidation may be equally important. (C) 2010 Elsevier B.V. All rights reserved.

  • 19.
    Jansson, Christer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Almkvist, E.
    Jansson, Per-Erik.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Heat balance of an asphalt surface: observations and physically-based simulations2006In: Meteorological Applications, ISSN 1350-4827, E-ISSN 1469-8080, Vol. 13, no 2, p. 203-212Article in journal (Refereed)
    Abstract [en]

    A physically-based 1-D beat and mass transfer model was tested to estimate the beat fluxes of an asphalt surface. The model was run for two summer months for a road test site in southwest Sweden. Parameters for thermal properties, surface runoff, radiation and turbulent transfer were obtained from a description of the road stratification and from the literature. Coefficients of determination (r(2)) 0.94, 0.93 and 0.97 were obtained when simulated results were compared with observations of net radiation, beat flow below the surface and surface temperature respectively, all with slope coefficients close to unity. In addition, simulation results elucidated the robe of water vapour transport through the asphalt-soil profile and its effect on the latent beat flow from the surface. Problems were identified with closure of the beat balance in measurements based on discrepancy between simulated and observed sensible heat flux.

  • 20.
    Jansson, Christer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Espeby, Bengt
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Preferential water flow in a glacial till soil2005In: Nordic Hydrology, ISSN 0029-1277, Vol. 36, no 1, p. 1-11Article in journal (Refereed)
    Abstract [en]

    Measured and simulated response of runoff during snowmelt has suggested that preferential water flow occurs as part of the infiltration process in glacial till. However, only a few quantitative studies have been presented. TDR measurements of soil water content were performed during the growing period in a till slope (7-10%) outside Stockholm. Soil cores were used to determine the water retention curve and the saturated hydraulic conductivity. A physically based one-dimensional model was used to simulate soil water dynamics in the slope. Two simulation approaches were used: a strict one-domain Darcian approach and a two-domain approach accounting for a bypass of the matrix flow system. The measured response of soil water content occurred within the first few hours after rainfall. This was best represented by the two-domain approach, while the response for the one-domain approach was significantly delayed with time and depth. The general behaviour of the soil water content throughout the season was, however, best simulated with a one-domain approach. The results indicated that preferential flow patterns through the unsaturated zone does not need to be considered to describe the seasonal pattern in glacial till soil. However, the results also point out that the purpose of the simulation is decisive when choosing a simulation approach, depending on whether the general soil water content over the season or the instant behaviour immediately after rainfall is of major interest.

  • 21.
    Jansson, Christer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Simulating impact on evapotranspiration vegetated surfacesManuscript (Other academic)
  • 22.
    Jansson, Christer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Near surface climate in an urban vegetated park and its surroundings2007In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 89, no 34, p. 185-193Article in journal (Refereed)
    Abstract [en]

    Near surface climate was observed through temperature profiling from the surface to 2.47 m height in an urban vegetated park and its surroundings in central Stockholm, Sweden. Measurements were conducted during three summer days by mobile traverses. Air temperature differences between the built-up area and the park were in the range of 0.5-0.8°C during the day and reached a maximum of 2°C at sunset. The thermal stratification of the air was mainly stable in the park and unstable in the built-up area. Inverse air temperature profiles in the park were less stable in open than in shady areas, and close to neutral at midday. The most unstable air was found in the north-south orientated canyons in the early afternoon. Possible heat advection from the surroundings, and thus uncoupling between the surface and the air, was identified through temperature gradients pointing at different directions within the 2.47 m profile. Examples at midday indicated that warm air advected as far as 150 m into the park.

  • 23. Jansson, P.E
    et al.
    Karlberg, L
    Theory and practice of coupled heat and mass transfer model for soil-plant-atmosphere system2009Book (Refereed)
  • 24.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Coupmodel: Model use, calibration, and validation2012In: American Society of Agricultural and Biological Engineers. Transactions, ISSN 2151-0032, E-ISSN 2151-0040, Vol. 55, no 4, p. 1335-1344Article in journal (Refereed)
    Abstract [en]

    The Coup Model has been developed to represent a platform with various modules that can be linked together for the user's specific application. This article provides a review of the model development, calibration procedures, and previous applications. For each application, the user can select different modules and specify how they should be linked. In the next step, appropriate inputs to run the model are specified based on the choice of modules. By offering water, heat, tracer, chloride, nitrogen, and carbon modules, the CoupModel allows the user to simulate a wide range of soil-plant-atmosphere interactions for any terrestrial ecosystem. The spatial distribution is lumped or distributed to any user-defined scale, and the temporal resolution is from minutes to hundreds of years. The platform allows the user to specify inputs as (1) forcing time series, (2) simple predefined patterns of variation by parameter functions, or (3) dynamic parameters that change value at specified dates during the simulation. Output variables from simulations can be compared with any independent measurement either as a time series or as a single value. The performance is expressed using conventional statistical indicators or as log likelihood sums. Simulations are made as single runs to represent a unique input or as a multiple series of simulations based on random or systematic sampling of parameter values. Parameters can also represent an object that is a collection of different parameters to represent a particular system, such as a soil profile. Two possible approaches may be used for calibration: Bayesian or generalized likelihood uncertainty estimation (GLUE). The former uses a Markov chain Monte Carlo (MCMC) method to sample among parameter values based on predefined error parameters for estimation of log likelihoods. Experience has shown that one can learn both how to improve measurements and how to understand the importance of model structural errors by using uncertainty-based calibration methods. The major advantage of GLUE compared to Bayesian calibration is that the learning process is simple and flexible. Bayesian calibration requires Gaussian distributions of residuals, which in many cases are not justified, and also requires careful consideration of error functions prior to the simulations. Although in some applications with a single output variable the Bayesian method is most suitable, for many multiple-criteria problems the flexibility of the GLUE approach is favored over the elegance of the Bayesian framework.

  • 25.
    Jansson, Per-Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Karlberg, Louise
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Theory and practice of coupled heat and mass transfer model for soil-plant-atmosphere system2009Book (Refereed)
  • 26.
    Jansson, Per-Erik.
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Moon, D. S.
    A coupled model of water, heat and mass transfer using object orientation to improve flexibility and functionality2001In: Environmental Modelling & Software, ISSN 1364-8152, E-ISSN 1873-6726, Vol. 16, no 1, p. 37-46Article in journal (Refereed)
    Abstract [en]

    The challenge of our software development is to introduce user-friendly document-orientation and graphical features that are typical in Windows software and to retain the possibility of easily extending existing legacy Fortran code. Keys to this development were the use of five development tools and our special management of shared memory. Numerical development of the code was thus continued in Fortran while the newly introduced multiple-document interface allows the new graphical features that are considered more user friendly (e.g. tool bar, status bar, animation, etc.) can be further refined and adjusted using Visual C++6.0 and the MS Visual Studio. Object orientation makes it possible to include modules with different type of dependencies that restrict the user interface to the specific use of the model. A large number of sub-models are combined and all input/output data have been adapted to an object-oriented standard. Multiple-run features and built-in links to a common database are new important features.

  • 27.
    Jansson, Per-Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Svensson, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Berggren Kleja, Dan
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Simulated climate change impacts on fluxes of carbon in Norway spruce ecosystems along a climatic transect in Sweden2008In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 89, no 1, p. 81-94Article in journal (Refereed)
    Abstract [en]

    A simulation study based on recent regional climate scenarios for Sweden investigated possible changes in carbon (C) dynamics and net ecosystem exchange (NEE) of Swedish Norway spruce forest ecosystems. Four sites, representative of well-drained soils in four regions, were included. Stand development was simulated for a 100-year rotation period using a coupled model describing abiotic and biotic processes in the soil-plant-atmosphere system. Two IPCC climate change scenarios, corresponding to a mean annual temperature increase of about 2 degrees C (A2) or 3 degrees C (B2) from the reference period 1961-1990 to a new period 2061-2090, were considered. Annual maximum snow depth decreased with the increase in air temperature, whereas maximum soil frost depth and mean annual soil temperature showed only small changes, especially for the sites in northern Sweden. Simulations suggested that in the warmer climate, gross primary production (GPP) increased by 24-32% in northern Sweden and by 32-43% in the south. In the north, the increase was related to the combined effect of air and soil temperature extending the growing season, whereas in the south it was mainly governed by increased N availability due to increased soil temperature. NEE increased by about 20% (A2) or 25% (B2) at all sites, more or less solely due to increased accumulation of C in the tree biomass (including harvest residues), since changes in soil C were small compared with the current climate. Both light use efficiency and water use efficiency were improved in the future climate scenarios, despite increases in atmospheric CO2 not being considered.

  • 28.
    Juston, John
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Andrén, Olof
    Department of Soil and Environment, SLU, Uppsala, Sweden.
    Kätterer, Thomas
    Department of Soil and Environment, SLU, Uppsala, Sweden.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Uncertainty analyses for calibrating a soil carbon balance model to agricultural field trial data in Sweden and Kenya2010In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 221, no 16, p. 1880-1888Article in journal (Refereed)
    Abstract [en]

    How do additional data of the same and/or different type contribute to reducing model parameter and predictive uncertainties? Most modeling applications of soil organic carbon (SOC) time series in agricultural field trial datasets have been conducted without accounting for model parameter uncertainty. There have been recent advances with Monte Carlo-based uncertainty analyses in the field of hydrological modeling that are applicable, relevant and potentially valuable in modeling the dynamics of SOC. Here we employed a Monte Carlo method with threshold screening known as Generalized Likelihood Uncertainty Estimation (GLUE) to calibrate the Introductory Carbon Balance Model (ICBM) to long-term field trail data from Ultuna, Sweden and Machang'a, Kenya. Calibration results are presented in terms of parameter distributions and credibility bands on time series simulations for a number of case studies. Using these methods, we demonstrate that widely uncertain model parameters, as well as strong covariance between inert pool size and rate constant parameters, exist when root mean square simulation errors were within uncertainties in input estimations and data observations. We show that even rough estimates of the inert pool (perhaps from chemical analysis) can be quite valuable to reduce uncertainties in model parameters. In fact, such estimates were more effective at reducing parameter and predictive uncertainty than an additional 16 years time series data at Ultuna. We also demonstrate an effective method to jointly, simultaneously and in principle more robustly calibrate model parameters to multiple datasets across different climatic regions within an uncertainty framework. These methods and approaches should have benefits for use with other SOC models and datasets as well.

  • 29.
    Juston, John
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Rating curve uncertainty and change detection in discharge time series: Case study with 44-year historic data from the Nyangores River, Kenya2014In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, no 4, p. 2509-2523Article in journal (Refereed)
    Abstract [en]

    The intersection of the developing topic of rating curve and discharge series uncertainty with the topic of hydrological change detection (e.g., in response to land cover or climatic change) has not yet been well studied. The work herein explores this intersection, with consideration of a long-term discharge response (1964-2007) for a ~650-km2 headwater basin of the Mara River in west Kenya, starting with stream rating and daily gauge height data. A rating model was calibrated using Bayesian methods to quantify uncertainty intervals in model parameters and predictions. There was an unknown balance of random and systemic error in rating data scatter (a scenario not likely unique to this basin), which led to an unknown balance of noise and information in the calibrated statistical error model. This had implications on testing for hydrological change. Overall, indications were that shifts in basin's discharge response were rather subtle over the 44-year period. A null hypothesis for change using flow duration curves (FDCs) from four different 8-year data intervals could be either accepted or rejected over much of the net flow domain depending on different applications of the statistical error model (each with precedence in the literature). The only unambiguous indication of change in FDC comparisons appeared to be a reduction in lowest baseflow in recent years (flows with >98% exceedance probability). We defined a subjective uncertainty interval based on an intermediate balance of random and systematic error in the rating model that suggested a possibility of more prevalent impacts. These results have relevance to management in the Mara basin and to future studies that might establish linkages to historic land use and climatic factors. The concern about uncertain uncertainty intervals (uncertainty2) extends beyond the Mara and is relevant to testing change where non-random rating errors may be important and subtle responses are investigated.

  • 30.
    Kalantari, Zahra
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Management and Assessment.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE).
    French, Helen K.
    Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, Ås, Norway.
    Folkeson, Lennart
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Management and Assessment.
    Sassner, Mona
    DHI Sverige AB, Stockholm, Sweden.
    Stolte, Jannes
    Norwegian Insitute for Agricultural and Environmental Research, Bioforsk, Soil and Environement division, Ås, Norway.
    Evaluating the effects of simulated land use changes on peak discharge of a catchment adjoining a roadManuscript (preprint) (Other academic)
    Abstract [en]

    The consequences of heavy rainfall and other extreme weather events are strongly influenced by land use within watersheds. The tested catchment consists of arable land, forest, living areas, and a creek which crosses a main road at the bottom of the catchment. The theoretical hydrological responses to different land use changes and four different extreme events were quantified by model simulations using MIKE-SHE. Land use composition and configuration was found to affect discharge; clear-cutting on 30% of the catchment area produced a 60% increase in peak discharge and a 10% increase in total runoff during a 50-year summer event. There were only small effects on peak discharge during smaller storms. Reforestation of 60% of basin area was the most effective measure to reduce peak flow, mainly for smaller (2-, 5- and 10-year) storms. Grassed waterways reduced water velocity in the stream and resulted in a 28% reduction in peak flow at the catchment outlet with the same 50-year event. A smaller degree of reforestation (30%) of the basin area was the most efficient measure to decrease total runoff. Hence different measures may be the most efficient for peak discharges and total runoff from the area. The specific effect of land use measures on catchment discharge depends on their spatial distribution and on the size and time of storm events.

  • 31.
    Kalantari, Zahra
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Sassner, Mona
    Stolte, Jannes
    Modelling high resolution discharge dynamics nearby road structure, using data from small catchment and 3 different models2011In: Proceedings, IAHR Conference, 34rd Congress, Brisbane, Australia, 26 June-1 July 2011, 2011, p. 226-232Conference paper (Other academic)
    Abstract [en]

    The climate change may lead to an increase in the frequency of extreme precipitation events and floods as well as changes in frost/thawing cycles. This will have impacts on the performance and life time of road infrastructures. The frequency of road closures and other incidences will probably increase.This paper is based on an ongoing collaboration with ClimRunoff project financed by the Norwegian Research Council. The results from this cooperation will be used in the research project financed by the Swedish Road Administration.This study has started with the focus on quantifying discharge of catchment areas draining towards roads. The first priority of this study is to create a model that can evaluate the run-off situations under spring situation (i.e. overland flow due to snowmelt and partially frozen soils). This modeling study has just been carried out for a small agricultural catchment in Norway using 3 different models (MIKE SHE, LISEM and CoupModel). This study aims at:

    • Evaluation of suitable hydrological models to quantify the spring discharge

    • Identification of problems with available data and models to quantify the role of climate impacts

    • Identifying the specific role of groundwater and surface runoff to the discharge dynamics

    The models evaluated differ with respect to aggregation level (time and space) and representation of the hydrological processes. Especially winter related processes as snow accumulation, melt and infiltration into partially frozen soils are discussed.

  • 32.
    Kalantari, Zahra
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Management and Assessment.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE).
    Stolte, Jannes
    Norwegian Insitute for Agricultural and Environmental Research, Bioforsk, Soil and Environement division, Ås, Norway.
    Folkeson, Lennart
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Management and Assessment.
    French, Helen K.
    Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, Ås, Norway.
    Sassner, Mona
    DHI Sverige AB, Stockholm, Sweden.
    Usefulness of four hydrological models in simulating high-resolution discharge dynamics of a adjacent to a roadManuscript (preprint) (Other academic)
    Abstract [en]

    Four hydrological models (LISEM, MIKE SHE, CoupModel and HBV) were compared with respect to their capability to predict peak flow in a small catchment upstream of a road in SE Norway on an hourly basis. All four models were calibrated using hourly observed streamflow. Simulated and observed discharge generated during three types of hydrological situations characteristic of winter/spring conditions causing overland flow were considered: snowmelt, partially frozen soil and heavy rain events. Using parameter sets optimised for winter/spring conditions, flows simulated by HBV coupled with CoupModel were comparable to measured discharge from the catchment in corresponding periods. However, this combination was best when all the parameters were calibrated in HBV. For ungauged basins with no real-time monitoring of discharge and when the spatial distribution is important, MIKE SHE may be more suitable than the other models, but the lack of detailed input data and the uncertainty in physical parameters should be considered. LISEM is potentially capable of calculating runoff from small catchments during winter/spring but requires better description of snowmelt, infiltration into frozen layers and tile drainage. From a practical road maintenance perspective, the usefulness and accuracy of a model depends on its ability to represent site-specific processes, data availability and calibration requirements.  

  • 33.
    Kalantari, Zahra
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Lyon, Stve W.
    Folkeson, Lennart
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    French, Helen K.
    Stolte, Jannes
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Sassner, Mona
    Quantifying the hydrological impact of simulated changes in land use on peak discharge in a small catchment2014In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 466-467, p. 741-754Article in journal (Refereed)
    Abstract [en]

    A physically-based, distributed hydrological model (MIKE SHE) was used to quantify overland runoff in response to four extreme rain events and four types of simulated land use measure in a catchment in Norway. The current land use in the catchment comprises arable lands, forest, urban areas and a stream that passes under a motorway at the catchment outlet. This model simulation study demonstrates how the composition and configuration of land use measures affect discharge at the catchment outlet differently in response to storms of different sizes. For example, clear-cutting on 30% of the catchment area produced a 60% increase in peak discharge and a 10% increase in total runoff resulting from a 50-year storm event in summer, but the effects on peak discharge were less pronounced during smaller storms. Reforestation of 60% of the catchment area was the most effective measure in reducing peak flows for smaller (2-, 5- and 10-year) storms. Introducing grassed waterways reduced water velocity in the stream and resulted in a 28% reduction in peak flow at the catchment outlet for the 50-year storm event. Overall, the results indicate that the specific effect of land use measures on catchment discharge depends on their spatial distribution and on the size and timing of storm events.

  • 34.
    Kalantari, Zahra
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. Stockholm University, Sweden .
    Lyon, Stve W.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Stolte, Jannes
    French, Helen K.
    Folkeson, Lennart
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Sassner, Mona
    Modeller subjectivity and calibration impacts on hydrological model applications: An event-based comparison for a road-adjacent catchment in south-east Norway2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 502, p. 315-329Article in journal (Refereed)
    Abstract [en]

    Identifying a 'best' performing hydrologic model in a practical sense is difficult due to the potential influences of modeller subjectivity on, for example, calibration procedure and parameter selection. This is especially true for model applications at the event scale where the prevailing catchment conditions can have a strong impact on apparent model performance and suitability. In this study, two lumped models (CoupModel and HBV) and two physically-based distributed models (LISEM and MIKE SHE) were applied to a small catchment upstream of a road in south-eastern Norway. All models were calibrated to a single event representing typical winter conditions in the region and then applied to various other winter events to investigate the potential impact of calibration period and methodology on model performance. Peak flow and event-based hydrographs were simulated differently by all models leading to differences in apparent model performance under this application. In this case study, the lumped models appeared to be better suited for hydrological events that differed from the calibration event (i.e., events when runoff was generated from rain on non-frozen soils rather than from rain and snowmelt on frozen soil) while the more physical-based approaches appeared better suited during snowmelt and frozen soil conditions more consistent with the event-specific calibration. This was due to the combination of variations in subsurface conditions over the eight events considered, the subsequent ability of the models to represent the impact of the conditions (particularly when subsurface conditions varied greatly from the calibration event), and the different approaches adopted to calibrate the models. These results indicate that hydrologic models may not only need to be selected on a case-by-case basis but also have their performance evaluated on an application-by-application basis since how a model is applied can be equally important as inherent model structure.

  • 35.
    Karlberg, Louise
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Annandale, John G
    University of Pretoria.
    Jansson, Per-Erik
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Rockström, Johan
    Stockholm Enivironment Institute.
    Steyn, J Martin
    University of Pretoria.
    Long-term impact of different management strategies for low-cost drip-irrigation systems using saline water: modelling two hypothetical agricultural systems in South AfricaIn: Agricultural and Forest Meteorology, ISSN 0168-1923, E-ISSN 1873-2240Article in journal (Other academic)
  • 36.
    Karlberg, Louise
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Ben-Gal, Alon
    Gilat Research Centre, Israel.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Shani, Uri
    Modelling transpiration and growth in salinity-stressed tomato under different climatic conditions2006In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 190, no 1-2, p. 15-40Article in journal (Refereed)
    Abstract [en]

    Models aiming to simulate growth under salinity stress and varied climatic conditions must rely on accurate methods for predicting transpiration and photosynthesis. Traditionally, models have described salinity stress as a decrease in water uptake caused by a low osmotic potential in the soil; however, many physiological studies suggest that reduced plant growth observed under saline conditions could be caused by increased respiration. Explicit calculation of photosynthesis and respiration enables both approaches to be tested and compared in a simulation model. We used an integrated ecosystems model (the CoupModel) to simulate photosynthesis and transpiration over a range of salinities. The model was calibrated and tested on two sets of data (two different seasons) on saline water, drip-irrigated tomato from lysimeter trials in the Arava Valley, Israel. Yields for the spring season were significantly lower than during the first autumn season even though transpiration was higher. As a result, water use efficiency differed by a factor of two between seasons. The model was successful in capturing this large variation, which was caused primarily by high levels of radiation and vapour pressure deficits during spring. For autumn the salinity stress approach in which water uptake was reduced performed well, whereas during spring the increased respiration approach correlated better with measurements. The concept of water use efficiency was found to be a useful tool for interpreting the accumulated effects of climatic and environmental conditions on particular agricultural systems. An attempt to simulate tomatoes grown in production beds indicated that the model set-up was also able to describe conventional cropping systems

  • 37. Karlberg, Louise
    et al.
    Gustafsson, David
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Modeling carbon turnover in five terrestrial ecosystems in the boreal zone using multiple criteria of acceptance2006In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 35, no 8, p. 448-458Article in journal (Refereed)
    Abstract [en]

    Estimates of carbon fluxes and turnover in ecosystems are key elements in the understanding of climate change and in predicting the accumulation of trace elements in the biosphere. In this paper we present estimates of carbon fluxes and turnover times for five terrestrial ecosystems using a modeling approach. Multiple criteria of acceptance were used to parameterize the model, thus incorporating large amounts of multi-faceted empirical data in the simulations in a standardized manner. Mean turnover times of carbon were found to be rather similar between systems with a few exceptions, even though the size of both the pools and the fluxes varied substantially. Depending on the route of the carbon through the ecosystem, turnover times varied from less than one year to more than one hundred, which may be of importance when considering trace element transport and retention. The parameterization method was useful both in the estimation of unknown parameters, and to identify variability in carbon turnover in the selected ecosystems.

  • 38.
    Karlberg, Louise
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Modelling carbon and water flows in terrestrial ecosystems in the boreal zone: Examples from Oskarshamn2006Report (Other academic)
  • 39.
    Karlberg, Louise
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Model-based evaluation of low-cost drip-irrigation systems and management strategies using saline water2007In: Irrigation science, ISSN 0342-7188, E-ISSN 1432-1319, Vol. 25, no 4, p. 387-399Article in journal (Refereed)
    Abstract [en]

    A drip-irrigation module was developed and included in an ecosystem model and tested on two independent datasets, spring and autumn, on field-grown tomato. Simulated soil evaporation correlated well with measurements for spring (2.62 mm d(-1) compared to 2.60 mm d(-1)). Changes in soil water content were less well portrayed by the model (spring r(2) = 0.27; autumn r(2) = 0.45). More independent data is needed for further model testing in combination with developments of the spatial representation of below-ground variables. In a fresh-water drip-irrigated system, about 30% of the incoming water was transpired, 40% was lost as non-productive evaporative flows, and the remainder left the system as surface runoff or drainage. Simulations showed that saline water irrigation (6 dS m(-1)) caused reduced transpiration, which led to higher drainage and soil evaporation, compared with fresh water. Covering the soil with plastic mulch resulted in an increase in yield and transpiration. Finally, two different drip-irrigation discharge rates (0.2 and 2.5 l h(-1)) were compared; however the simulations indicated that the discharge rate did not have any impact on the partitioning of the incoming water to the system. The model proved to be a useful tool for evaluating the importance of specific management options.

  • 40. Katterer, T.
    et al.
    Andren, O.
    Jansson, Per-Erik.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Pedotransfer functions for estimating plant available water and bulk density in Swedish agricultural soils2006In: Acta Agriculturae Scandinavica - Section B, ISSN 0906-4710, E-ISSN 1651-1913, Vol. 56, no 4, p. 263-276Article in journal (Refereed)
    Abstract [en]

    Pedotransfer functions (PTFs) to estimate plant available water were developed from a database of arable soils in Sweden. The PTFs were developed to fulfil the minimum requirements of any agro-hydrological application, i.e., soil water content at wilting point (theta(wp)) and field capacity (theta(fc)),from information that frequently is available from soil surveys such as texture and soil organic carbon content (SOC). From the same variables we also estimated bulk density (rho) and porosity (epsilon), which seldom are included in surveys, but are needed for calculating element mass balances. The seven particle-size classes given in the data set were aggregated in different ways to match information commonly gained from surveys. Analysis of covariance and stepwise multiple linear regression were used for quantifying the influence of depth, particle size class, textural class and soil organic carbon on the characteristic variables. PTFs developed from other data sets were also tested and their goodness-of-fit and bias was evaluated. These functions and those developed for the Swedish database were also tested on an independent data set and finally ranked according to their goodness of fit. Among single independent variables, clay was the best predictor for theta(wp), sand ( or the sum of clay and silt) for theta(fc) and SOC for rho and epsilon. A large fraction of the variation in theta(wp) and theta(fc) is explained by soil texture and SOC ( up to 90%) and root mean square errors (RMSEs) were as small as 0.03 m(3) water m(-3) soil in the best models. For the prediction of rho and epsilon in the test data set, the best PTF could only explain 40-43% of the total variance with corresponding RMSEs of 0.14 g cm(-3) and 5.3% by volume, respectively. Recently presented PTFs derived from a North American database performed very well for estimating theta(wp) ( low error and bias) and could be recommended for Swedish soils if measurements of clay, sand and SOC were available. Although somewhat less accurately, also theta(fc) could be estimated satisfactorily. This indicates that the determination of plant available water by texture and SOC is rather independent of soil genesis and that certain PTFs are transferable between continents.

  • 41. Khoshkhoo, Y.
    et al.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Irannejad, P.
    Khalili, A.
    Rahimi, H.
    Calibration of an energy balance model to simulate wintertime soil temperature, soil frost depth, and snow depth for a 14year period in a highland area of Iran2015In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 119, p. 47-60Article in journal (Refereed)
    Abstract [en]

    A physically-based heat and mass transfer model, CoupModel, is calibrated to simulate wintertime soil temperature, soil frost depth, and snow depth for a 14-year period in a highland area of Iran. A Monte Carlo based approach is used for calibration process based on subjective performance criteria. Sensitivity and uncertainty analyses of the model were performed by selecting 30 parameters and the model was run using 22,000 samples taken from the uncertainty range of the parameters. By using the Nash-Sutcliffe Index to evaluate the performance of the model and applying a cutoff threshold for the performance to snow depth and soil temperature, 161 behavioral simulations were recognized and considered as the accepted ensemble to represent the field conditions. Sensitivity analysis of the model revealed some parameters associated with soil evaporation, soil hydraulic properties, and snow modeling as sensitive and highly important parameters. Uncertainty analysis of the model for wintertime soil temperatures showed a reasonable agreement between simulations and observations in most cases. However, a systematic error occurred at some periods because of high uncertainty of the actual snow density and details of snow melting. Uncertainties were also due to the simplified model assumptions regarding snow thermal properties and temperature within snow cover. The snow depth at the accumulation and melting stages were described well by the model in most cases.

  • 42. Klemedtsson, Leif
    et al.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Karlberg, Louise
    Weslien, Per
    von Arnold, Karin
    Ernfors, Maria
    Langvall, Ola
    Lindroth, Anders
    Bayesian calibration method used to elucidate carbon turnover in forest on drained organic soil2008In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 89, no 1, p. 61-79Article in journal (Refereed)
    Abstract [en]

    Depending on the balance between sink and source processes for C, drained organic forest soil ecosystems can be in balance or act as net sinks or sources of CO2 to the atmosphere. In order to study the effect of groundwater level and soil temperature on C-flux, the CoupModel was calibrated (climate data, groundwater levels, soil CO2 flux, net ecosystem fluxes of CO2-exchange, sensible heat flux and latent heat flux, forest production etc.) for a drained forest in Sweden. Bayesian calibration techniques were used to elucidate how different parameters and variables were interlinked in C-circulation. The calibrated model reproduced abiotic and biotic variables reasonably well except for root respiration, which was largely underestimated. Bayesian calibration reduced the uncertainties in the model and highlighted the fact that calibrations should be performed with a high number of parameters instead of specific parameter values.

  • 43.
    Lindström, Riitta
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Prediction of high rate infiltration in typical Swed-ish soil profilesArticle in journal (Other academic)
  • 44.
    Lundmark, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Estimating the fate of de-icing salt in a roadside environment by combining modelling and field observations2008In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 195, no 1-4, p. 215-232Article in journal (Refereed)
    Abstract [en]

    Predicting the environmental effects of de-icing salt requires knowledge of the pathways taken by salt from on-road application through spread to the surroundings to deposition and fate in the roadside environment. This study described differences in chloride deposition and distribution in soil with increasing distance from the road by means of field observations and modelling. The dynamic modelling approach successfully represented the spread of de-icing salt from road to surroundings, deposition in the roadside environment and the subsequent infiltration into roadside soil. The general decrease in soil chloride content with distance from the road was described by differences in salt deposition, soil physical properties, vegetation properties and snow characteristics. The uncertainty in model predictions was highest in areas close to the road due to a complex combination of high salt deposition, snow-ploughed masses and road runoff. The exponential decline in salt deposition with distance from the road could not be justified close to the road. Different types of field investigations were applied in a calibration procedure to establish reasonable ranges for the most influential model parameters. Measured electrical resistivity reflected well the changes in simulated chloride content in soil during winter and spring when chloride concentrations were high. However, during summer or periods with low chloride concentrations the measured resistivity was substantially lower than simulated values, as it reflected the total contamination level in soil.

  • 45.
    Lundmark, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Generic soil descriptions for modelling water and chloride dynamics in the unsaturated zone based on Swedish soils2009In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 150, no 1-2, p. 85-95Article in journal (Refereed)
    Abstract [en]

    Information about soil hydraulic properties is a prerequisite for modelling water and solute dynamics in the unsaturated zone. Providing that this information is available and the uncertainty is within an acceptable range, computer models can be helpful tools in quantifying environmental effects. This study describes the water retention curve and hydraulic conductivity for three soil types: clay, glacial till and sand. These soils originated from a Swedish database containing 2200 measured soil layers representing 260 soil profiles. A simulation experiment was conducted where daily variations in water and chloride were simulated for a 20-year period in central Sweden, using the different soil profiles sampled from the database. Two approaches to calculate effective parameters were tested, in order to obtain generic soil descriptions and examine their ability to represent the average of the variation in chloride and water characteristics obtained for the respective soil type. In general, the use of these effective parameters was successful but overestimations of the water and chloride outflow occurred in the clay, which presented high spatial variability, and of the chloride concentration in the sand, which presented high temporal variability. Overall, the generic soil descriptions were useful in producing reasonable behaviour regarding water and chloride dynamics and could be recommended for general assessments of the environmental impact of non-reactive solutes from ;areas where simplified soil classifications are available.

  • 46.
    Lundmark, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Regional GIS-linked model to monitor the environmental impacts of de-icing saltManuscript (Other academic)
  • 47.
    Lundmark, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Transfer of de-icing salt by road runoff and aerial dispersal under the influence of snow ploughingIn: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694Article in journal (Refereed)
  • 48.
    Lundmark, Annika
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Lindström, Riitta
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Effects of soil, vegetation and ground-water level on hydrogeological turnover timesIn: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707Article in journal (Other academic)
  • 49. Matthews, B.
    et al.
    Netherer, S.
    Katzensteiner, K.
    Pennerstorfer, J.
    Blackwell, E.
    Henschke, P.
    Hietz, P.
    Rosner, S.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Schume, H.
    Schopf, A.
    Transpiration deficits increase host susceptibility to bark beetle attack: Experimental observations and practical outcomes for Ips typographus hazard assessment2018In: Agricultural and Forest Meteorology, ISSN 0168-1923, E-ISSN 1873-2240, Vol. 263, p. 69-89Article in journal (Refereed)
    Abstract [en]

    The projected increase in the frequency and severity with which bark beetle disturbances occur is forecasted to be partially driven by increases in drought episodes. Drought is widely considered to predispose host conifer trees to bark beetle attack; however, experimental data supporting this hypothesis are scarce. This study revisits the Rosalia Roof Project, the first throughfall manipulation experiment to investigate how attack by the Eurasian spruce bark beetle (Ips typographus) on mature Norway spruce (Picea abies) trees is affected by drought stress. Using the in situ “attack box” method, this study explores whether increased host acceptance by I. typographus and/or reduced host defense against attack coincide with increased tree transpiration deficits (i.e. the reduction from a potential transpiration caused by soil water limitation). To estimate transpiration deficits of the respective control and drought stress-induced (full-cover) trees, sap flow measurements were combined with simulations from a simple forest water balance routine. The model, which was calibrated against in situ hydrological measurements, has been developed for a hazard rating tool (PHENIPS-TDEF) which simulates both potential I. typographus phenology and tree drought stress in Norway spruce stands. While host acceptance appeared unaffected by tree transpiration deficits, acute and chronic transpiration deficits did lead to reduced host defense. Full cover trees for instance, which experienced an estimated 93 mm transpiration deficit in the previous May-Sep, could only defend against <10% of the total individual attack attempts between spring and midsummer compared to the control trees which experienced a corresponding deficit of 9 mm and defended >70% of attacks. However, similar defended attack percentages on the full-cover and control trees during late summer demonstrate the difficulty in deriving simple stress proxy-infestation risk relationships. The experiment therefore highlights the utility and limitations of transpiration deficits within I. typographus disturbance models and hazard assessment tools, such as PHENIPS-TDEF. 

  • 50.
    Metzger, Christine
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. Technische Universität München, Chai. of Restoration EcologyFreising, Germany .
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Lohila, A.
    Aurela, M.
    Eickenscheidt, T.
    Belelli-Marchesini, L.
    Dinsmore, K. J.
    Drewer, J.
    van Huissteden, J.
    Droesler, M.
    CO2 fluxes and ecosystem dynamics at five European treeless peatlands - merging data and process oriented modeling2015In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 12, no 1, p. 125-146Article in journal (Refereed)
    Abstract [en]

    The carbon dioxide (CO2) exchange of five different peatland systems across Europe with a wide gradient in land use intensity, water table depth, soil fertility and climate was simulated with the process oriented CoupModel. The aim of the study was to find out whether CO2 fluxes, measured at different sites, can be explained by common processes and parameters or to what extend a site specific configuration is needed. The model was calibrated to fit measured CO2 fluxes, soil temperature, snow depth and leaf area index (LAI) and resulting differences in model parameters were analyzed. Finding site independent model parameters would mean that differences in the measured fluxes could be explained solely by model input data: water table, meteorological data, management and soil inventory data. Seasonal variability in the major fluxes was well captured, when a site independent configuration was utilized for most of the parameters. Parameters that differed between sites included the rate of soil organic decomposition, photosynthetic efficiency, and regulation of the mobile carbon (C) pool from senescence to shooting in the next year. The largest difference between sites was the rate coefficient for heterotrophic respiration. Setting it to a common value would lead to underestimation of mean total respiration by a factor of 2.8 up to an overestimation by a factor of 4. Despite testing a wide range of different responses to soil water and temperature, rate coefficients for heterotrophic respiration were consistently the lowest on formerly drained sites and the highest on the managed sites. Substrate decomposability, pH and vegetation characteristics are possible explanations for the differences in decomposition rates. Specific parameter values for the timing of plant shooting and senescence, the photosynthesis response to temperature, litter fall and plant respiration rates, leaf morphology and allocation fractions of new assimilates, were not needed, even though the gradient in site latitude ranged from 48 degrees N (southern Germany) to 68 degrees N (northern Finland) differed largely in their vegetation. This was also true for common parameters defining the moisture and temperature response for decomposition, leading to the conclusion that a site specific interpretation of these processes is not necessary. In contrast, the rate of soil organic decomposition, photosynthetic efficiency, and the regulation of the mobile carbon pool need to be estimated from available information on specific soil conditions, vegetation and management of the ecosystems, to be able to describe CO2 fluxes under different conditions.

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