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- He, Hongxing, 1987, et al.
(författare)
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Modeling Nitrous Oxide emissions and identifying emission controlling factors for a spruce forest ecosystem on drained organic soil
- 2013
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Ingår i: European Geosciences Union, Vienna Austria 07 – 12 April 2013.
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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%.
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- He, Hongxing, 1987, et al.
(författare)
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Modeling Nitrous Oxide emissions and identifying emission controlling factors for a spruce forest ecosystem on drained organic soil
- 2015
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Ingår i: Geophysical Research Abstracts. ; 17:EGU2015-10451
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- High Nitrous Oxide (N2O) emission has been identified in hemiboreal forests on drained organic soils. However, the controlling factors regulating the emissions have been unclear. To examine the importance of different factors on the N2O emission in a spruce forest on drained organic soil, a process-based model, CoupModel, was calibrated by the generalized likelihood uncertainty estimation (GLUE) method. 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 accumulated measured N2O emissions, but showed difficulties to capture all the measured emission peaks. Parameter uncertainties could be reduced by combining selected criteria with the measurement data. The model showed the N2O emissions during the summer to be controlled mainly by the competition between plants and microbes while during the winter season snow melt periods are important. The simulated N budget shows >100 kg N ha-1 yr-1 to be in circulation between soil and plants and back again. Each year the peat mineralization adds about 60 kg N ha-1 and atmospheric deposition 12 kg N ha-1. Most of the mineralized litter and peat N is directly taken up by the plants but only a part accumulates in the plant biomass. As long as no timber is harvested the main N loss from the system is through nitrate leaching (30 kg N ha-1 yr-1) and gas emissions (20 kg N ha-1 yr-1), 55% as NO, 27% as N2O and 18% as N2. Regarding N2O gas emissions, our modeling indicates denitrification to be the most responsible process, of the size 6 kg N ha-1 yr-1, which could be compared to 0.04 kg N ha-1 yr-1 from nitrification. Our modelling also reveal 88% of the N2O mainly to be produced by denitrification in the capillary fringe (c.a. 40-60 cm below soil surface) of the anaerobic zone using nitrate produced in the upper more aerobic layers. We conclude N2O production/emission to be controlled mainly by the complex interaction between soil N availability, mediated by mineralization, nitrification, and plant growth together with soil anaerobicity controlled by the groundwater level. The model is currently used for modelling greenhouse gas emissions from drained organic soils over the entire forest cycle, from plantation to harvest. Different land use and plant production are compared like Spruce, Willow and Reed Canary Grass as well as rewetting options.
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- Huang, Xiao, et al.
(författare)
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The MYR Project (2018-21): Climate smart management practices on Norwegian organic soils
- 2019
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Ingår i: Geophysical Research Abstracts Vol. 21, EGU2019-7918, 2019.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cultivated organic soils account for∼7% of Norway’s agricultural land area, and they are estimated to be a significant source of greenhouse gas (GHG) emissions. The project ‘Climate smart management practices on Norwegian organic soils’ (MYR), commissioned by the Research Council of Norway (decision no. 281109), aims to evaluate GHG (e.g. carbon dioxide, methane and nitrous oxide) emissions and impacts on biomass productivity from three land use types (cultivated, abandoned and restored) on organic soils. At the cultivated sites, impacts of drainage depth and management intensity will be measured. We established experimental sites in Norway covering a broad range of climate and management regimes, which will produce observational data in high spatio-temporal resolution during 2019-2021. Using state-of-the-art modelling techniques, MYR aims to predict the potential GHG mitigation under different scenarios. Four models (BASGRA, DNDC, Coup and ECOSSE) will be further developed according to the soil properties, and then used independently in simulating biogeochemical processes and biomass dynamics in the different land uses. Robust parameterization schemes for each model will be based in the observational data from the project for both soil and crop combinations. Eventually, a multi-model ensemble prediction will be carried out to provide scenario analyses by 2030 and 2050. By integrating experimental results and modelling, the project aims at generating useful information for recommendations on environment-friendly use of Norwegian peatlands.
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- Kasimir, Åsa, 1956, et al.
(författare)
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Lower greenhouse gas flux and better economy with wetter peat soil use
- 2019
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Ingår i: Geophysical Research AbstractsVol. 21, EGU2019-14821, 2019.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have used the CoupModel to investigate effects of 80 years of peatland use on greenhouse gas (GHG) emissions for four scenarios (1) business as usual - Norway spruce with average soil water table depth (WTD) of -40 cm; (2) willow plantation with WTD at -20 cm; (3) reed canary grass production with WTD at -10 cm; and (4) a fully rewetted peatland with no harvested product. Total soil GHG emissions for the scenarios were (including litter and peat respiration CO2 emissions as well as N2O and CH4) on average 33, 19, 15, and 11 Mg CO2eq ha-1year-1. No peat was lost for the wet peatland. At WTD -10 cm GHG emissions were at a minimum. Economy was analyzed by a cost–benefit analysis (CBA) where scenario (1) with spruce included gain from sold products like timber, pulpwood and energy biomass, and scenarios (2) and (3) harvests were for bioenergy purpose. Stored C in biomass and litter was included as gains, as well as biodiversity gains for the rewetted scenario. Costs included management and soil emissions. The CBA showed on average the best result for the rewetted peatland (4) and next were willow (2) together with reed canary grass (3), while spruce (1) production economic benefit was the lowest. This showed wetter condition to be a gain for the climate as well as for the economy. Questions to resolve are influences of fluctuating water tables and vegetation types on CH4 and N2O emission as well as DOC/DON loss etc. Continuation Clear-cut of forest followed by either continued forest or wetland restoration. We are now to clear-cut the mature spruce forest at Skogaryd research station, on which the model was calibrated. Half the area will then still be drained and planted with spruce and the other half rewetted to a wet meadow by building a dam. Collection of ecosystem and flux data will continue. We will now use the model to investigate the two scenarios, where we are most interested in effects on GHG and water DOC/DON losses, results presented here.We will also gain further knowledge on GHG and other losses from agricultural peat soils in the project Climate Smart Use of Norwegian organic soils (MYR). We will calibrate the CoupModel on data generated from the project and use it for investigating alternative land use options (wetter soil and lower management intensity at cultivated peatlands). In this later step, we want co-operate with research groups using other models.
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- Kasimir, Åsa, 1956, et al.
(författare)
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Spruce forest on drained peat – clear-cut winter 2019, half replanted and half rewetted into meadow
- 2019
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Ingår i: Abstract Book. pp 128.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have used the CoupModel to investigate effects on GHG emissions as well as on economy of 80 years of peatland use for four scenarios (1) business as usual – Norway spruce with average soil water table depth (WTD) of -40 cm; (2) willow plantation with WTD at -20 cm; (3) reed canary grass production with WTD at -10 cm; and (4) a fully rewetted peatland with no harvested product. Total soil GHG emissions for the scenarios were (including litter and peat respiration CO2 emissions as well as N2O and CH4) on average 33, 19, 15, and 11 Mg CO2eq ha-1 yr-1. No peat was lost for the wet peatland. GHG emissions were at a minimum at WTD -10 cm. Economy was analyzed by a cost – benefit analysis (CBA) where scenario (1) with spruce included gain from sold products like timber, pulpwood and energy biomass, and scenarios (2) and (3) gains from energy biomass. Gains over the 80 years resulted also from stored C in biomass and litter as well as biodiversity for scenario (4). Costs included management and soil emissions. The CBA showed on average the best result for the rewetted peatland (4) while spruce (1) production’s economic benefit was the lowest. We are now about to clear-cut the mature spruce forest at Skogaryd research station, on which the model was calibrated. Half the area will then still be drained and planted with spruce and the other half rewetted to a wet meadow by building a dam. Collection of ecosystem and flux data has been extensive for more than a decennia and will continue. Researchers are invited for investigations following the changes taking place after the clear cut. We will present projected losses to air and water estimated by the CoupModel.
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- Klemedtsson, Åsa Kasimir, 1956, et al.
(författare)
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Climate mitigation scenarios of drained peat soils
- 2014
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Ingår i: European Geosciences Union General Assembly 2014 Vienna, Austria, 27 April – 02 May 2014.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The national inventory reports (NIR) submitted to the UNFCCC show Sweden – which as many other countries has wetlands where parts have been drained for agriculture and forestry purposes, – to annually emit 12 million tonnes carbon dioxide equivalents, which is more GHG’es than industrial energy use release in Sweden. Similar conditions can be found in other northern countries, having cool and wet conditions, naturally promoting peat accumulation, and where land use management over the last centuries have promoted draining activities. These drained peatland, though covering only 2% of the land area, have emissions corresponding to 20% of the total reported NIR emissions. This substantial emission contribution, however, is hidden within the Land Use Land Use Change and Forestry sector (LULUCF) where the forest Carbon uptake is even larger, which causes the peat soil emissions become invisible. The only drained soil emission accounted in the Swedish Kyoto reporting is the N2O emission from agricultural drained organic soils of the size 0.5 million tonnes CO2e yr-1. This lack of visibility has made incentives for land use change and management neither implemented nor suggested, however with large potential. Rewetting has the potential to decrease soil mineralization, why CO2 and N2O emissions are mitigated. However if the soil becomes very wet CH4 emission will increase together with hampered plant growth. By ecological modeling, using the CoupModel the climate change mitigation potential have been estimated for four different land use scenarios; 1, Drained peat soil with Spruce (business as usual scenario), 2, raised ground water level to 20 cm depth and Willow plantation, 3, raised ground water level to 10 cm depth and Reed Canary Grass, and 4, rewetting to an average water level in the soil surface with recolonizing wetland plants and mosses. We calculate the volume of biomass production per year, peat decomposition, N2O emission together with nitrate and DOC/POC leakage. Based on the modelling results a cost benefit analysis is performed (economics), guiding to the design of environmental policies needed for land use change to come true.
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- Klemedtsson, Åsa Kasimir, 1956, et al.
(författare)
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Low nitrous oxide emission from organic management results in efficient production
- 2012
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Ingår i: Planet under Pressure, new knowledge towards solutions, Poster session 2.
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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.
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