| 1. |
- Pärn, J., et al.
(författare)
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Nitrogen-rich organic soils under warm well-drained conditions are global nitrous oxide emission hotspots
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Nitrous oxide (N2O) is a powerful greenhouse gas and the main driver of stratospheric ozone depletion. Since soils are the largest source of N2O, predicting soil response to changes in climate or land use is central to understanding and managing N2O. Here we find that N2O flux can be predicted by models incorporating soil nitrate concentration (NO3 -), water content and temperature using a global field survey of N2O emissions and potential driving factors across a wide range of organic soils. N2O emissions increase with NO3 - and follow a bell-shaped distribution with water content. Combining the two functions explains 72% of N2O emission from all organic soils. Above 5 mg NO3 --N kg-1, either draining wet soils or irrigating well-drained soils increases N2O emission by orders of magnitude. As soil temperature together with NO3 - explains 69% of N2O emission, tropical wetlands should be a priority for N2O management.
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| 2. |
- Pattaro, Cristian, et al.
(författare)
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Genetic associations at 53 loci highlight cell types and biological pathways relevant for kidney function
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Reduced glomerular filtration rate defines chronic kidney disease and is associated with cardiovascular and all-cause mortality. We conducted a meta-analysis of genome-wide association studies for estimated glomerular filtration rate (eGFR), combining data across 133,413 individuals with replication in up to 42,166 individuals. We identify 24 new and confirm 29 previously identified loci. Of these 53 loci, 19 associate with eGFR among individuals with diabetes. Using bioinformatics, we show that identified genes at eGFR loci are enriched for expression in kidney tissues and in pathways relevant for kidney development and transmembrane transporter activity, kidney structure, and regulation of glucose metabolism. Chromatin state mapping and DNase I hypersensitivity analyses across adult tissues demonstrate preferential mapping of associated variants to regulatory regions in kidney but not extra-renal tissues. These findings suggest that genetic determinants of eGFR are mediated largely through direct effects within the kidney and highlight important cell types and biological pathways.
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| 3. |
- Gharahi Ghehi, N., et al.
(författare)
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N2O and NO emission from the Nyungwe tropical highland rainforest in Rwanda
- 2014
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Ingår i: Geoderma Regional. - 2352-0094. ; 2-3, s. 41-49
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Tidskriftsartikel (refereegranskat)abstract
- Tropical forest soils are a significant source for N2O and NO. Current estimates of N2O and NO emissions are uncertain due to the limited number of fieldmeasurements and model input data. Furthermore, considerable spatial and temporal variability exists due to variation of soil properties, vegetation characteristics and meteorology.We used a process-based model (ForestDNDC-tropica) to estimate N2O and NO emissions from the entire (970 km2) tropical highland forest (Nyungwe) in southwestern Rwanda. Scaling these results to that regional level using legacy soil, meteorological and simulated vegetation data we found in most cases agreement between N2O and NO measurements and model predictions. Limited agreement was found for acid soils with high clay content and reduced metals, indicating that abiotic N2O and NO forming processes in acidic soils might be under-represented in the current ForestDNDC-tropica model. The Nyungwe forest was estimated to emit 439 t N2O-N year−1 (2.8– 5.5 kg N2O-N ha−1 year−1) and 244 t NO-N year−1 (0.8–5.1 kg N ha−1 year−1), corroborating previous studies in tropical forests and highlighting that also tropical highland rainforest soils are a major source of atmospheric N2O and NO. The uncertainty for the N2O and NO emission estimates was 153 and 50 t N2O-N year−1 and 36 and 16 t NO-N year−1 considering uncertainty in model input data and annual variability, respectively. The results showed that soil bulk density and pH were the most influential factors driving spatial variation and model uncertainty. To improve global model-based estimates of N2O and NO emission from tropical forest focus should therefore also be oriented in delivering more detailed soil and vegetation data.
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| 4. |
- Meyer, Astrid, et al.
(författare)
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Integrating mycorrhiza in a complex model system: effects on ecosystem C and N fluxes
- 2012
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Ingår i: European Journal of Forest Research. - : Springer Science and Business Media LLC. - 1612-4669 .- 1612-4677. ; 131:6, s. 1809-1831
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Tidskriftsartikel (refereegranskat)abstract
- During the last decades, ectomycorrhiza has been identified to be of major importance for ecosystem carbon (C) and nitrogen (N) cycling and tree growth. Despite this importance, mycorrhiza has largely been neglected in ecosystem models or regarded only implicitly by a static mycorrhiza term. In order to overcome this limitation, we integrated the dynamic mycorrhiza model MYCOFON (Meyer et al. in Plant Soil 327:493-517, 2010a, Plant Soil 327:519, 2010b) into the ecosystem modelling framework MoBiLE (Modular Biosphere simuLation Environment) and coupled it to available forest growth and development process models. Model testing was done for different beech and spruce forest sites in Germany. Simulation results were compared to a standard model set-up, that is, without explicit consideration of mycorrhiza. Parameters were set in order not to violate previous findings about C partitioning into aboveground and belowground biomasses. Nevertheless, the explicit consideration of mycorrhiza let to considerable differences between sites and deposition scenarios with respect to simulated root biomass, plant nitrogen supply, and gaseous soil C and N emissions. The latter was mainly a result of differences in soil N concentration and dynamics. Our simulation results also show that the C supply to mycorrhizal fungi by plants as well as the importance of mycorrhizal fungi for plant N uptake, that is, the allocation of C and N between plants and fungi, depends on the magnitude of N deposition. This effect is neglected by standard model approaches so far. Therefore, explicit consideration of mycorrhiza in ecosystem models has a high potential to improve model simulations of ecosystem C and N cycling and associated biosphere-hydrosphere-atmosphere exchange processes and consequently simulation of soil CO2 and N trace gas emissions from forest sites.
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