| 1. |
- Dahl, Martin, et al.
(författare)
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Effects of shading and simulated grazing on carbon sequestration in a tropical seagrass meadow
- 2016
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 104:3, s. 654-664
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Tidskriftsartikel (refereegranskat)abstract
- 1. There is an ongoing world-wide decline of seagrass ecosystems, one of the world's most efficient carbon sink habitats. In spite of this, there is a clear lack of studies experimentally testing the effects of anthropogenic disturbances on carbon sequestration of seagrass systems. 2. We assessed the effects of two disturbances of global concern on the carbon sink function in a five-month in situ experiment within a tropical seagrass (Thalassia hemprichii) meadow by testing the impacts of shading and simulated grazing at two levels of intensity using shading cloths and clipping of shoot tissue. We measured the effects of these disturbances on the carbon sequestration process by assessing the net community production (NCP), carbon and nitrogen content in tissue biomass, and organic matter and THAA (total hydrolysable amino acids) in the sediment down to 40 cm depth. 3. Treatments of high-intensity shading and high-intensity clipping were similarly impacted and showed a significantly lower NCP and carbon content in the below-ground biomass compared to the seagrass control. No significant effects were seen in organic carbon, total nitrogen, C:N ratio and THAA in the sediment for the seagrass treatments. However, both clipping treatments showed different depth profiles of carbon and THAA compared to the seagrass control, with lower organic carbon and THAA content in the surface sediment. This can be explained by the clipping of shoot tissue causing a less efficient trapping of allochthonous carbon and reduced input of shredded seagrass leaves to the detritus sediment layer. In the clipping plots, erosion of the surface sediment occurred, which was also most likely caused by the removal of above-ground plant biomass. 4. Synthesis. Our findings show that during the course of this experiment, there were no impacts on the sedimentary carbon while the high-intensity disturbances caused a clear depletion of carbon biomass and reduced the seagrass meadow's capacity to sequester carbon. From a long-term perspective, the observed effect on the carbon biomass pool in the high-intensity treatments and the sediment erosion in the clipping plots may lead to loss in sedimentary carbon.
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| 2. |
- Estenberg, Martin, 1970-
(författare)
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"Ett snäpp högre" : En studie av historielärares hanterande av tankeredskap.
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Abstract The aim with this study is to examine how practicing history teachers in upper secondary school deal with historical thinking concepts. The three main questions are: which concepts do teachers use in their courses and when do they use them? How can teachers’ use of different historical thinking concepts be described in terms of reconstruction and construction? What factors influence teachers when they work with historical thinking concepts? To answer these questions, the material, for example tests, lesson plans and notes of seven teachers has been analyzed. These analysis were followed by interviews with the teachers. The empirical data have been handled in two steps. The first step is a survey of what historical thinking concepts teachers use and when they use them. The survey was done as a detailed reading of the teachers’ material. In this survey two historical thinking concepts, evidence and cause and consequence, have been selected for further analysis, which is the second step. The results show that when teachers deal with the historical thinking concept of evidence they show their students models and ways to handle evidence. This is not the case when teachers handle the historical thinking concept of cause and consequence. Models are shown here as well but not to the same extent. The result also shows that the teachers’ handling of evidence in a greater extent leads to construction compared with their handling of cause and consequence. The explanations provided in the study also point to the different character between the two concepts and what form of test the teachers’ use and what words are used to communicate for example cause and consequence. Furthermore, the explanations also indicate that the teachers’ view of what historical knowledge contains of, together with what kind of students and what other subject they teach play some part in their dealing with historical thinking concepts.
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| 3. |
- Gullström, Martin, et al.
(författare)
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Blue Carbon Storage in Tropical Seagrass Meadows Relates to Carbonate Stock Dynamics, Plant–Sediment Processes, and Landscape Context : Insights from the Western Indian Ocean
- 2018
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Ingår i: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 21:3, s. 551-566
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Tidskriftsartikel (refereegranskat)abstract
- Globally, seagrass ecosystems are considered major blue carbon sinks and thus indirect contributors to climate change mitigation. Quantitative estimates and multi-scale appraisals of sources that underlie long-term storage of sedimentary carbon are vital for understanding coastal carbon dynamics. Across a tropical–subtropical coastal continuum in the Western Indian Ocean, we estimated organic (Corg) and inorganic (Ccarb) carbon stocks in seagrass sediment. Quantified levels and variability of the two carbon stocks were evaluated with regard to the relative importance of environmental attributes in terms of plant–sediment properties and landscape configuration. The explored seagrass habitats encompassed low to moderate levels of sedimentary Corg (ranging from 0.20 to 1.44% on average depending on species- and site-specific variability) but higher than unvegetated areas (ranging from 0.09 to 0.33% depending on site-specific variability), suggesting that some of the seagrass areas (at tropical Zanzibar in particular) are potentially important as carbon sinks. The amount of sedimentary inorganic carbon as carbonate (Ccarb) clearly corresponded to Corg levels, and as carbonates may represent a carbon source, this could diminish the strength of seagrass sediments as carbon sinks in the region. Partial least squares modelling indicated that variations in sedimentary Corg and Ccarb stocks in seagrass habitats were primarily predicted by sediment density (indicating a negative relationship with the content of carbon stocks) and landscape configuration (indicating a positive effect of seagrass meadow area, relative to the area of other major coastal habitats, on carbon stocks), while seagrass structural complexity also contributed, though to a lesser extent, to model performance. The findings suggest that accurate carbon sink assessments require an understanding of plant–sediment processes as well as better knowledge of how sedimentary carbon dynamics are driven by cross-habitat links and sink–source relationships in a scale-dependent landscape context, which should be a priority for carbon sink conservation.
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| 5. |
- Hillberg, Emil, et al.
(författare)
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Active Network Management for All : ANM4L a collaborative research project
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Developments of the power system are driven by the need to decrease the environmental footprint, to meet international climate goals, pushing for fossil‐free energy system. The transition towards clean energy will require power systems to adapt on a global scale with significant investments needed in fossil‐free electricity generation and transport. Renewable Energy Sources (RES) play an increasingly important role in the power system and may become the dominant sources of electricity. Significant RES are integrated in distribution grids globally, resulting in an increased need for distribution grids to perform new and complex tasks necessary for continued grid stability. The rapidity of small‐scale investments calls for agile, alternative grid development solutions. This agility is furthermore necessary to meet challenges arising from demand scenarios encompassing intermittent renewables along with electrification of transport and heat sectors. New technologies and markets are emerging to provide flexibility in consumption, generation, and power transfer capacity. Active Network Management (ANM) solutions provides alternative methods for planning and operation of the power system, through monitoring and control of multiple grid assets. This paper presents an overview of the ongoing project ANM4L, where a toolbox will be developed to support operation and planning of distribution grids.The project ANM4L (Active network management for all - anm4l.eu), will develop and demonstrate innovative ANM solutions for increasing integration of distributed generation in electricity distribution systems. ANM solutions will consider management of active and reactive power to avoid overload situations and maintain voltage limits. The goal is to decrease the need of curtailment of renewable energy, theoretically enabling further integration of distributed generation potentially even above the current design limitations of the electricity network. Core research and development activities of the ANM4L project include development of: ANM methods for local energy systems. Economic considerations to provide decision support. A toolbox to support the planning and operation. The toolbox, methods and business models for ANM will be demonstrated in real life distribution grids in both Sweden and Hungary. Furthermore, the project will consider the replicability and scalability necessary for these ANM solutions to be applied across the EU.
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| 7. |
- Svanborg, Catharina, et al.
(författare)
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Adhesion, signal transduction and mucosal inflammation
- 2002
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Ingår i: Bacterial Adhesion to Host Tissues. - Cambridge : Cambridge University Press. - 9780521801072 - 0521801079 ; , s. 223-246
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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