| 1. |
- Klemedtsson, Leif, 1953, et al.
(författare)
-
Skogaryd – Integration of terrestrial and freshwater greenhouse gas sources and sinks
- 2010
-
Ingår i: 1st COST meeting ‘Belowground carbon in Europeanforest’, Birmensdorf, Switzerland, 26–28 January 2010..
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Forests play an important role in the global carbon (C) cycle, and management as well as climate can cause major effects on the balance of C between the atmosphere and the plant/soil system. With re-gard to our commitments to the Kyoto and post-Kyoto actions on climate change, we need reliable predictions on how this balance is affected by management and climate. In 2006 the Skogaryd Research Forest was established in the southwest of Sweden (58°23’N, 12°09’E). The overall goal is to quantify net greenhouse gas (GHG) fluxes from drained spruce forest, by determining the individual fluxes and pools of C and nitrogen and elucidating their connection to site fertility, drainage status and abiotic parameters and then use the generated data in GHG models, for model validations and ultimately emissions predictions. During 2006-2009 the research has fo-cused on two sites, mineral and organic, dominated by Norway spruce (Picea abies). Both sites are drained fertile soils but with different land-use history that have affected their physical properties. Measurements includes: net ecosystem exchange of CO2, Shoot photosynthesis and respiration at different locations within the canopy, stem respiration, emissions of N2O and CH4 using manual cham-bers, soil respiration with automatic chambers including a trenching experiment where root-, mycelia-, and heterotrophic respiration are separated, fine root production using minirhizotrons, and mycelia production. The organic site also includes a wood ash experiment. From 2010 the research will be expanded to the whole watershed, from the mire system via streams, riparian zones, forests, to lakes and the subsequent exchange between the atmosphere and surface waters. Different terrestrial and limnic ecosystems will be linked holistically, using site specific tech-niques at different scales, from aircraft (km2) to chambers (m2) to create integrated models that can be used to quantify net GHG flux for management strategies.
|
|
| 2. |
- He, Hongxing, 1987, et al.
(författare)
-
Modeling Nitrous Oxide emissions and identifying emission controlling factors for a spruce forest ecosystem on drained organic soil
- 2013
-
Ingår i: European Geosciences Union, Vienna Austria 07 – 12 April 2013.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- High nitrous oxide (N2O) emission potential has been identified in hemiboreal forest on drained Histosols. However, the environmental factors regulating the emissions were unclear. To investigate the importance of different factors on the N2O emission, a modeling approach was accomplished, using CoupModel with Monti-Carlo based multi-criteria calibration method. The model was made to represent a forest on drained peat soil in south-west Sweden where data of fluxes combined with soil properties and plant conditions were used. The model outcome was consistent with measurements of abiotic (soil temperature, net radiation, groundwater level and soil moisture) and biotic responses (net ecosystem exchange and soil respiration). Both dynamics and magnitude of N2O emissions were well simulated compared to measurements (8.7±2.1 kg N/ha/year). The performance indicators for an ensemble of accepted simulations of N2O emission dynamics and magnitudes were correlated to calibrated parameters related to soil anaerobic fraction and atmospheric nitrogen deposition (correlation coefficient, r≥0.4). A weak correlation with N2O emission dynamics was also found for biotic responses (r≥0.3). However, the ME of simulated and measured N2O emissions was better correlated to the ME of soil moisture (r=-0.6), and also to the ME of both the soil temperature (r=0.53) and groundwater level (r=-0.7). Groundwater level (range from -0.8m to -0.13m) was identified as the most important environmental factor regulating the N2O emissions for present forest soil. Profile analysis indicated that N2O was mainly produced in the deeper layers (≥0.35m) of the soil profile. The optimum soil moisture for N2O production was around 70%.
|
|
| 3. |
- Klemedtsson, Åsa Kasimir, 1956, et al.
(författare)
-
Low nitrous oxide emission from organic management results in efficient production
- 2012
-
Ingår i: Planet under Pressure, new knowledge towards solutions, Poster session 2.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We compare nitrous oxide (N2O) emission due to organic and integrated conventional farming systems on a research farm "Logården" in south-west Sweden. The soil is characterized by an average clay content of 40%. Both systems have 7 year crop rotations since 1991. Faba beans and spring wheat crops in each management system are compared. The faba bean crops did not receive any nitrogen addition. The organic fields were weeded by hoe while the integrated fields had an under-sown catch crop. Spring wheat followed the next year after the beans, where both managements had a green manure crop under-sown. Fertiliser is only given to the conventional field, 110 kg N ha-1. N2O emission rate was measured by manual chambers during two years. Gas samples were collected every second week and more frequent during freeze/thaw events and at management occasions. Integrated beans had significantly higher emissions (2.3 kg N2O-N ha-1) than the organic. The organic wheat had the significantly lowest average N2O emission (0.2 kg N2O-N ha-1) one year out of two The overall emission is governed by very few occasions of high emissions, mainly in spring and autumn but not specifically following fertiliser addition. We try to explain the causal factors. Yield-scaled N2O emission (emitted N2O-N per harvested N) was found low for both management systems producing wheat but only for the organic faba beans, all having ca 10 g N2O-N kg-1 harvested N, which was twice as high for the integrated beans. Based on our results we discuss options for sustainable and productive agricultural management characterised by low emissions.
|
|
| 4. |
- Klemedtsson, Åsa Kasimir, 1956, et al.
(författare)
-
Organic field beans have low nitrous oxide emissions and high N-efficiency
- 2011
-
Ingår i: Nitrogen & Global Change 2011, Key Findings - Future Challenges.
-
Konferensbidrag (refereegranskat)abstract
- It has earlier been argued that organic farming is not as efficient as conventional, concerning yields and N retention. In search for agricultural systems having high N-efficiency and low N2O emission we have measured nitrous oxide (N2O) emission in organic and conventional (integrated) fields. In contrast to the suspicions we found in average a fairly low N2O emission for the organic beans (in average 0.39 kg N ha-1 y-1), also lower than conventional beans (2.3 kg N ha-1 y-1). The efficiency of the agricultural system can be expressed as N2O intensity, emission per harvest, aiming for a low number. The organic beans had the lowest intensity compared to the conventional beans (6 g respectively 22 g N2 Methods/ApproachO-N per kg N in harvest), this due to larger emission for conventional beans. The lower harvest for organic beans had a small impact on the intensity. The high emissions for conventional cropping system were found in autumn after harvest and RoundUp application, mitigation options may be found here.
|
|
| 5. |
|
|
| 6. |
- Nylinder, Josefine, 1974, et al.
(författare)
-
Modelling uncertainty for nitrate leaching and nitrous oxide emissions based on a Swedish field experiment with organic crop rotation
- 2011
-
Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 0167-8809 .- 1873-2305. ; 141:1-2, s. 167-183
-
Tidskriftsartikel (refereegranskat)abstract
- High uncertainties are common in detailed quantification of the N budget of agricultural cropping systems. The process-based CoupModel, integrated with the parameter calibration method known as Generalized likelihood uncertainty estimation (GLUE), was used here to define parameter values and estimate an N budget based on experimental data from an organic farming experiment in south-west Sweden. Data on nitrate (NO3-) leaching and nitrous oxide (N2O) emissions were used as a basis for quantifying N budget pools. A complete N budget with uncertainties associated with the different components of the N cycle compartments for two different fields (B2 and B4) is presented. Simulated N2O emissions contributed 1-2% of total N output, which corresponded to 7% and 8.7% of total N leaching for B2 and B4, respectively. Measured N2O emissions contributed 3.5% and 10.3% of total N leaching from B2 and B4, respectively. Simulated N inputs (deposition, plant N fixation and fertilisation) and outputs (emissions, leaching and harvest) showed a relatively small range of uncertainty, while the differences in N storage in the soil exhibited a larger range of uncertainty. One-fifth of the GLUE-calibrated parameters had a significant impact on simulated NO3- leaching and/or N2O emissions data. Emissions of N2O were strongly associated with the nitrification process. The high degree of equifinality indicated that a simpler model could be calibrated to the same field data.
|
|
| 7. |
- Nylinder, Josefine, 1974
(författare)
-
Process-based modelling of N losses from terrestrial ecosystems
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nitrogen (N) loss to atmosphere and ground water can contribute to environmental destruction, by N emission as the greenhouse gas nitrous oxide (N2O) and by leaching of N to contamination and eutrophication of water. Dynamic models are important keys to increase the knowledge of ecosystems N processes. This thesis studied N fluxes, particularly soil N dynamics, in different ecosystems in relation to interactions between physical and biological processes using a process-based model called the CoupModel. A sub-model implementation of two important processes contributing to nitrogen oxide (NO), N2O, and dinitrogen gas (N2) emissions; nitrification and denitrification, from another process-based model (PnET-N-DNDC) was done. The models were applied on an old spruce forest in Germany and both model outputs of NO and N2O emissions were compared. After further development of the nitrification and denitrification sub-model, the CoupModel successfully described the general pattern of N dynamics. The CoupModel was thereafter applied to an organic crop rotation system. The model generated a complete N budget with small uncertainty ranges for simulated N inputs and outputs, but with a trade-off on estimated differences of N storage in the soil; why it could not be conclusively determined whether the system acted as a source or sink for N. As an outcome of the simulation, almost one fifth of the parameters that were calibrated could be identified as being either system- or field-dependent and had a significant impact on the simulation for nitrate leaching and N2O emission data. We used the CoupModel to evaluate N2O emission sensitivity to soil pH on an organic soil in a birch forest. By generating a decrease of the N2:N2O ratio in the CoupModel, we successfully described the increased N2O emission with decreasing soil pH. The simulated dynamic of N2O emission generated in a time delay compared to measurements, may be related to uncertainties in the model description of the groundwater dynamics and other processes involved. However, the CoupModel robustly managed to quantify total carbon and nitrogen budgets. Finally, we applied the CoupModel on data from ten different locations in Sweden with different N deposition and meteorological data. These were investigated for different drainage depth and initial soil N conditions. The soil differences had large impacts on both N mineral leaching and N denitrification. An application of selected parameter sets was tested; revealing that the uncertainty range of parameter values had impact on simulated N budgets, most notable so for the denitrification pool.
|
|
| 8. |
|
|
